Merge tag 'rcu.release.v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux
Pull RCU updates from Frederic Weisbecker:
"SRCU:
- Introduction of the new SRCU-lite flavour with a new pair of
srcu_read_[un]lock_lite() APIs. In practice the read side using
this flavour becomes lighter by removing a full memory barrier on
LOCK and a full memory barrier on UNLOCK. This comes at the expense
of a higher latency write side with two (in the best case of a
snaphot of unused read-sides) or more RCU grace periods on the
update side which now assumes by itself the whole full ordering
guarantee against the LOCK/UNLOCK counters on both indexes, along
with the accesses performed inside.
Uretprobes is a known potential user.
Note this doesn't replace the default normal flavour of SRCU which
still behaves the same as usual.
- Add testing of SRCU-lite through rcutorture and rcuscale
- Various cleanups on the way.
Fixes:
- Allow short-circuiting RCU-TASKS-RUDE grace periods on
architectures that have sane noinstr boundaries forbidding tracing
on low-level idle and kernel entry code. RCU-TASKS is enough on
such configurations because it involves an RCU grace period that
waits for all idle tasks to either schedule out voluntarily or
enter into RCU unwatched noinstr code.
- Allow and test start_poll_synchronize_rcu() with IRQs disabled.
- Mention rcuog kthreads in relevant documentation and Kconfig help
- Various fixes and consolidations
rcutorture:
- Add --no-affinity on tools to leave the affinity setting of guests
up to the user.
- Add guest_os_delay parameter to rcuscale for better warm-up
control.
- Fix and improve some rcuscale error handling.
- Various cleanups and fixes
stall:
- Remove dead code
- Stop dumping tasks if a stalled grace period eventually ended
midway as that only produces confusing output.
- Optimize detection of stalling CPUs and avoid useless node locking
otherwise.
NOCB:
- Fix rcu_barrier() hang due to a race against callbacks
deoffloading. This is not yet used, except by rcutorture, and waits
for its promised cpusets interface.
- Remove leftover function declaration"
* tag 'rcu.release.v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (42 commits)
rcuscale: Remove redundant WARN_ON_ONCE() splat
rcuscale: Do a proper cleanup if kfree_scale_init() fails
srcu: Unconditionally record srcu_read_lock_lite() in ->srcu_reader_flavor
srcu: Check for srcu_read_lock_lite() across all CPUs
srcu: Remove smp_mb() from srcu_read_unlock_lite()
rcutorture: Avoid printing cpu=-1 for no-fault RCU boost failure
rcuscale: Add guest_os_delay module parameter
refscale: Correct affinity check
torture: Add --no-affinity parameter to kvm.sh
rcu/nocb: Fix missed RCU barrier on deoffloading
rcu/kvfree: Fix data-race in __mod_timer / kvfree_call_rcu
rcu/srcutiny: don't return before reenabling preemption
rcu-tasks: Remove open-coded one-byte cmpxchg() emulation
doc: Remove kernel-parameters.txt entry for rcutorture.read_exit
rcutorture: Test start-poll primitives with interrupts disabled
rcu: Permit start_poll_synchronize_rcu*() with interrupts disabled
rcu: Allow short-circuiting of synchronize_rcu_tasks_rude()
doc: Add rcuog kthreads to kernel-per-CPU-kthreads.rst
rcu: Add rcuog kthreads to RCU_NOCB_CPU help text
rcu: Use the BITS_PER_LONG macro
...
diff --git a/Documentation/RCU/stallwarn.rst b/Documentation/RCU/stallwarn.rst
index ca7b7cd..30080ff 100644
--- a/Documentation/RCU/stallwarn.rst
+++ b/Documentation/RCU/stallwarn.rst
@@ -249,7 +249,7 @@
interrupts during the current stalled grace period.
The "idle=" portion of the message prints the dyntick-idle state.
-The hex number before the first "/" is the low-order 12 bits of the
+The hex number before the first "/" is the low-order 16 bits of the
dynticks counter, which will have an even-numbered value if the CPU
is in dyntick-idle mode and an odd-numbered value otherwise. The hex
number between the two "/"s is the value of the nesting, which will be
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index f287548..7e1315e 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5415,11 +5415,6 @@
Set time (jiffies) between CPU-hotplug operations,
or zero to disable CPU-hotplug testing.
- rcutorture.read_exit= [KNL]
- Set the number of read-then-exit kthreads used
- to test the interaction of RCU updaters and
- task-exit processing.
-
rcutorture.read_exit_burst= [KNL]
The number of times in a given read-then-exit
episode that a set of read-then-exit kthreads
@@ -5429,6 +5424,14 @@
The delay, in seconds, between successive
read-then-exit testing episodes.
+ rcutorture.reader_flavor= [KNL]
+ A bit mask indicating which readers to use.
+ If there is more than one bit set, the readers
+ are entered from low-order bit up, and are
+ exited in the opposite order. For SRCU, the
+ 0x1 bit is normal readers, 0x2 NMI-safe readers,
+ and 0x4 light-weight readers.
+
rcutorture.shuffle_interval= [KNL]
Set task-shuffle interval (s). Shuffling tasks
allows some CPUs to go into dyntick-idle mode
diff --git a/Documentation/admin-guide/kernel-per-CPU-kthreads.rst b/Documentation/admin-guide/kernel-per-CPU-kthreads.rst
index b6aeae33..ea7fa2a 100644
--- a/Documentation/admin-guide/kernel-per-CPU-kthreads.rst
+++ b/Documentation/admin-guide/kernel-per-CPU-kthreads.rst
@@ -315,7 +315,7 @@
to do.
Name:
- rcuop/%d and rcuos/%d
+ rcuop/%d, rcuos/%d, and rcuog/%d
Purpose:
Offload RCU callbacks from the corresponding CPU.
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 0ee270b..fe42315 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -165,7 +165,6 @@
static inline bool rcu_is_watching(void) { return true; }
static inline void rcu_momentary_eqs(void) { }
static inline void kfree_rcu_scheduler_running(void) { }
-static inline bool rcu_gp_might_be_stalled(void) { return false; }
/* Avoid RCU read-side critical sections leaking across. */
static inline void rcu_all_qs(void) { barrier(); }
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 90a684f..27d86d9 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -40,7 +40,6 @@
void rcu_barrier(void);
void rcu_momentary_eqs(void);
void kfree_rcu_scheduler_running(void);
-bool rcu_gp_might_be_stalled(void);
struct rcu_gp_oldstate {
unsigned long rgos_norm;
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 835bbb2..08339eb 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -56,6 +56,13 @@
void cleanup_srcu_struct(struct srcu_struct *ssp);
int __srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp);
void __srcu_read_unlock(struct srcu_struct *ssp, int idx) __releases(ssp);
+#ifdef CONFIG_TINY_SRCU
+#define __srcu_read_lock_lite __srcu_read_lock
+#define __srcu_read_unlock_lite __srcu_read_unlock
+#else // #ifdef CONFIG_TINY_SRCU
+int __srcu_read_lock_lite(struct srcu_struct *ssp) __acquires(ssp);
+void __srcu_read_unlock_lite(struct srcu_struct *ssp, int idx) __releases(ssp);
+#endif // #else // #ifdef CONFIG_TINY_SRCU
void synchronize_srcu(struct srcu_struct *ssp);
#define SRCU_GET_STATE_COMPLETED 0x1
@@ -176,17 +183,6 @@
#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
-#define SRCU_NMI_UNKNOWN 0x0
-#define SRCU_NMI_UNSAFE 0x1
-#define SRCU_NMI_SAFE 0x2
-
-#if defined(CONFIG_PROVE_RCU) && defined(CONFIG_TREE_SRCU)
-void srcu_check_nmi_safety(struct srcu_struct *ssp, bool nmi_safe);
-#else
-static inline void srcu_check_nmi_safety(struct srcu_struct *ssp,
- bool nmi_safe) { }
-#endif
-
/**
* srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing
@@ -236,33 +232,67 @@
* a mutex that is held elsewhere while calling synchronize_srcu() or
* synchronize_srcu_expedited().
*
- * Note that srcu_read_lock() and the matching srcu_read_unlock() must
- * occur in the same context, for example, it is illegal to invoke
- * srcu_read_unlock() in an irq handler if the matching srcu_read_lock()
- * was invoked in process context.
+ * The return value from srcu_read_lock() must be passed unaltered
+ * to the matching srcu_read_unlock(). Note that srcu_read_lock() and
+ * the matching srcu_read_unlock() must occur in the same context, for
+ * example, it is illegal to invoke srcu_read_unlock() in an irq handler
+ * if the matching srcu_read_lock() was invoked in process context. Or,
+ * for that matter to invoke srcu_read_unlock() from one task and the
+ * matching srcu_read_lock() from another.
*/
static inline int srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp)
{
int retval;
- srcu_check_nmi_safety(ssp, false);
+ srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL);
retval = __srcu_read_lock(ssp);
srcu_lock_acquire(&ssp->dep_map);
return retval;
}
/**
+ * srcu_read_lock_lite - register a new reader for an SRCU-protected structure.
+ * @ssp: srcu_struct in which to register the new reader.
+ *
+ * Enter an SRCU read-side critical section, but for a light-weight
+ * smp_mb()-free reader. See srcu_read_lock() for more information.
+ *
+ * If srcu_read_lock_lite() is ever used on an srcu_struct structure,
+ * then none of the other flavors may be used, whether before, during,
+ * or after. Note that grace-period auto-expediting is disabled for _lite
+ * srcu_struct structures because auto-expedited grace periods invoke
+ * synchronize_rcu_expedited(), IPIs and all.
+ *
+ * Note that srcu_read_lock_lite() can be invoked only from those contexts
+ * where RCU is watching, that is, from contexts where it would be legal
+ * to invoke rcu_read_lock(). Otherwise, lockdep will complain.
+ */
+static inline int srcu_read_lock_lite(struct srcu_struct *ssp) __acquires(ssp)
+{
+ int retval;
+
+ srcu_check_read_flavor_lite(ssp);
+ retval = __srcu_read_lock_lite(ssp);
+ rcu_try_lock_acquire(&ssp->dep_map);
+ return retval;
+}
+
+/**
* srcu_read_lock_nmisafe - register a new reader for an SRCU-protected structure.
* @ssp: srcu_struct in which to register the new reader.
*
* Enter an SRCU read-side critical section, but in an NMI-safe manner.
* See srcu_read_lock() for more information.
+ *
+ * If srcu_read_lock_nmisafe() is ever used on an srcu_struct structure,
+ * then none of the other flavors may be used, whether before, during,
+ * or after.
*/
static inline int srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp)
{
int retval;
- srcu_check_nmi_safety(ssp, true);
+ srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NMI);
retval = __srcu_read_lock_nmisafe(ssp);
rcu_try_lock_acquire(&ssp->dep_map);
return retval;
@@ -274,7 +304,7 @@
{
int retval;
- srcu_check_nmi_safety(ssp, false);
+ srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL);
retval = __srcu_read_lock(ssp);
return retval;
}
@@ -303,7 +333,7 @@
static inline int srcu_down_read(struct srcu_struct *ssp) __acquires(ssp)
{
WARN_ON_ONCE(in_nmi());
- srcu_check_nmi_safety(ssp, false);
+ srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL);
return __srcu_read_lock(ssp);
}
@@ -318,12 +348,28 @@
__releases(ssp)
{
WARN_ON_ONCE(idx & ~0x1);
- srcu_check_nmi_safety(ssp, false);
+ srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL);
srcu_lock_release(&ssp->dep_map);
__srcu_read_unlock(ssp, idx);
}
/**
+ * srcu_read_unlock_lite - unregister a old reader from an SRCU-protected structure.
+ * @ssp: srcu_struct in which to unregister the old reader.
+ * @idx: return value from corresponding srcu_read_lock().
+ *
+ * Exit a light-weight SRCU read-side critical section.
+ */
+static inline void srcu_read_unlock_lite(struct srcu_struct *ssp, int idx)
+ __releases(ssp)
+{
+ WARN_ON_ONCE(idx & ~0x1);
+ srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_LITE);
+ srcu_lock_release(&ssp->dep_map);
+ __srcu_read_unlock_lite(ssp, idx);
+}
+
+/**
* srcu_read_unlock_nmisafe - unregister a old reader from an SRCU-protected structure.
* @ssp: srcu_struct in which to unregister the old reader.
* @idx: return value from corresponding srcu_read_lock().
@@ -334,7 +380,7 @@
__releases(ssp)
{
WARN_ON_ONCE(idx & ~0x1);
- srcu_check_nmi_safety(ssp, true);
+ srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NMI);
rcu_lock_release(&ssp->dep_map);
__srcu_read_unlock_nmisafe(ssp, idx);
}
@@ -343,7 +389,7 @@
static inline notrace void
srcu_read_unlock_notrace(struct srcu_struct *ssp, int idx) __releases(ssp)
{
- srcu_check_nmi_safety(ssp, false);
+ srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL);
__srcu_read_unlock(ssp, idx);
}
@@ -360,7 +406,7 @@
{
WARN_ON_ONCE(idx & ~0x1);
WARN_ON_ONCE(in_nmi());
- srcu_check_nmi_safety(ssp, false);
+ srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL);
__srcu_read_unlock(ssp, idx);
}
diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h
index 4d96bbd..1321da8 100644
--- a/include/linux/srcutiny.h
+++ b/include/linux/srcutiny.h
@@ -81,6 +81,9 @@
synchronize_srcu(ssp);
}
+#define srcu_check_read_flavor(ssp, read_flavor) do { } while (0)
+#define srcu_check_read_flavor_lite(ssp) do { } while (0)
+
/* Defined here to avoid size increase for non-torture kernels. */
static inline void srcu_torture_stats_print(struct srcu_struct *ssp,
char *tt, char *tf)
diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index ed57598..490aeec 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -25,7 +25,7 @@
/* Read-side state. */
atomic_long_t srcu_lock_count[2]; /* Locks per CPU. */
atomic_long_t srcu_unlock_count[2]; /* Unlocks per CPU. */
- int srcu_nmi_safety; /* NMI-safe srcu_struct structure? */
+ int srcu_reader_flavor; /* Reader flavor for srcu_struct structure? */
/* Update-side state. */
spinlock_t __private lock ____cacheline_internodealigned_in_smp;
@@ -43,6 +43,11 @@
struct srcu_struct *ssp;
};
+/* Values for ->srcu_reader_flavor. */
+#define SRCU_READ_FLAVOR_NORMAL 0x1 // srcu_read_lock().
+#define SRCU_READ_FLAVOR_NMI 0x2 // srcu_read_lock_nmisafe().
+#define SRCU_READ_FLAVOR_LITE 0x4 // srcu_read_lock_lite().
+
/*
* Node in SRCU combining tree, similar in function to rcu_data.
*/
@@ -204,4 +209,64 @@
void srcu_barrier(struct srcu_struct *ssp);
void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf);
+/*
+ * Counts the new reader in the appropriate per-CPU element of the
+ * srcu_struct. Returns an index that must be passed to the matching
+ * srcu_read_unlock_lite().
+ *
+ * Note that this_cpu_inc() is an RCU read-side critical section either
+ * because it disables interrupts, because it is a single instruction,
+ * or because it is a read-modify-write atomic operation, depending on
+ * the whims of the architecture.
+ */
+static inline int __srcu_read_lock_lite(struct srcu_struct *ssp)
+{
+ int idx;
+
+ RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_lite().");
+ idx = READ_ONCE(ssp->srcu_idx) & 0x1;
+ this_cpu_inc(ssp->sda->srcu_lock_count[idx].counter); /* Y */
+ barrier(); /* Avoid leaking the critical section. */
+ return idx;
+}
+
+/*
+ * Removes the count for the old reader from the appropriate
+ * per-CPU element of the srcu_struct. Note that this may well be a
+ * different CPU than that which was incremented by the corresponding
+ * srcu_read_lock_lite(), but it must be within the same task.
+ *
+ * Note that this_cpu_inc() is an RCU read-side critical section either
+ * because it disables interrupts, because it is a single instruction,
+ * or because it is a read-modify-write atomic operation, depending on
+ * the whims of the architecture.
+ */
+static inline void __srcu_read_unlock_lite(struct srcu_struct *ssp, int idx)
+{
+ barrier(); /* Avoid leaking the critical section. */
+ this_cpu_inc(ssp->sda->srcu_unlock_count[idx].counter); /* Z */
+ RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_unlock_lite().");
+}
+
+void __srcu_check_read_flavor(struct srcu_struct *ssp, int read_flavor);
+
+// Record _lite() usage even for CONFIG_PROVE_RCU=n kernels.
+static inline void srcu_check_read_flavor_lite(struct srcu_struct *ssp)
+{
+ struct srcu_data *sdp = raw_cpu_ptr(ssp->sda);
+
+ if (likely(READ_ONCE(sdp->srcu_reader_flavor) & SRCU_READ_FLAVOR_LITE))
+ return;
+
+ // Note that the cmpxchg() in srcu_check_read_flavor() is fully ordered.
+ __srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_LITE);
+}
+
+// Record non-_lite() usage only for CONFIG_PROVE_RCU=y kernels.
+static inline void srcu_check_read_flavor(struct srcu_struct *ssp, int read_flavor)
+{
+ if (IS_ENABLED(CONFIG_PROVE_RCU))
+ __srcu_check_read_flavor(ssp, read_flavor);
+}
+
#endif
diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig
index 3e079de..b9b6bc5 100644
--- a/kernel/rcu/Kconfig
+++ b/kernel/rcu/Kconfig
@@ -249,16 +249,24 @@
workloads will incur significant increases in context-switch
rates.
- This option offloads callback invocation from the set of CPUs
- specified at boot time by the rcu_nocbs parameter. For each
- such CPU, a kthread ("rcuox/N") will be created to invoke
- callbacks, where the "N" is the CPU being offloaded, and where
- the "x" is "p" for RCU-preempt (PREEMPTION kernels) and "s" for
- RCU-sched (!PREEMPTION kernels). Nothing prevents this kthread
- from running on the specified CPUs, but (1) the kthreads may be
- preempted between each callback, and (2) affinity or cgroups can
- be used to force the kthreads to run on whatever set of CPUs is
- desired.
+ This option offloads callback invocation from the set of
+ CPUs specified at boot time by the rcu_nocbs parameter.
+ For each such CPU, a kthread ("rcuox/N") will be created to
+ invoke callbacks, where the "N" is the CPU being offloaded,
+ and where the "x" is "p" for RCU-preempt (PREEMPTION kernels)
+ and "s" for RCU-sched (!PREEMPTION kernels). This option
+ also creates another kthread for each sqrt(nr_cpu_ids) CPUs
+ ("rcuog/N", where N is the first CPU in that group to come
+ online), which handles grace periods for its group. Nothing
+ prevents these kthreads from running on the specified CPUs,
+ but (1) the kthreads may be preempted between each callback,
+ and (2) affinity or cgroups can be used to force the kthreads
+ to run on whatever set of CPUs is desired.
+
+ The sqrt(nr_cpu_ids) grouping may be overridden using the
+ rcutree.rcu_nocb_gp_stride kernel boot parameter. This can
+ be especially helpful for smaller numbers of CPUs, where
+ sqrt(nr_cpu_ids) can be a bit of a blunt instrument.
Say Y here if you need reduced OS jitter, despite added overhead.
Say N here if you are unsure.
diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
index 2599040..fadc08a 100644
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -120,7 +120,6 @@
void rcu_segcblist_add_len(struct rcu_segcblist *rsclp, long v);
void rcu_segcblist_init(struct rcu_segcblist *rsclp);
void rcu_segcblist_disable(struct rcu_segcblist *rsclp);
-void rcu_segcblist_offload(struct rcu_segcblist *rsclp, bool offload);
bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp);
bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp);
struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp);
diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
index 6d37596..0f3059b 100644
--- a/kernel/rcu/rcuscale.c
+++ b/kernel/rcu/rcuscale.c
@@ -889,14 +889,14 @@
if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start < 2 * HZ)) {
pr_alert("ERROR: call_rcu() CBs are not being lazy as expected!\n");
- WARN_ON_ONCE(1);
- return -1;
+ firsterr = -1;
+ goto unwind;
}
if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start > 3 * HZ)) {
pr_alert("ERROR: call_rcu() CBs are being too lazy!\n");
- WARN_ON_ONCE(1);
- return -1;
+ firsterr = -1;
+ goto unwind;
}
}
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index bb75dbf..2ae8a5e 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -57,9 +57,9 @@
/* Bits for ->extendables field, extendables param, and related definitions. */
#define RCUTORTURE_RDR_SHIFT_1 8 /* Put SRCU index in upper bits. */
-#define RCUTORTURE_RDR_MASK_1 (1 << RCUTORTURE_RDR_SHIFT_1)
-#define RCUTORTURE_RDR_SHIFT_2 9 /* Put SRCU index in upper bits. */
-#define RCUTORTURE_RDR_MASK_2 (1 << RCUTORTURE_RDR_SHIFT_2)
+#define RCUTORTURE_RDR_MASK_1 (0xff << RCUTORTURE_RDR_SHIFT_1)
+#define RCUTORTURE_RDR_SHIFT_2 16 /* Put SRCU index in upper bits. */
+#define RCUTORTURE_RDR_MASK_2 (0xff << RCUTORTURE_RDR_SHIFT_2)
#define RCUTORTURE_RDR_BH 0x01 /* Extend readers by disabling bh. */
#define RCUTORTURE_RDR_IRQ 0x02 /* ... disabling interrupts. */
#define RCUTORTURE_RDR_PREEMPT 0x04 /* ... disabling preemption. */
@@ -71,6 +71,9 @@
#define RCUTORTURE_MAX_EXTEND \
(RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
+#define RCUTORTURE_RDR_ALLBITS \
+ (RCUTORTURE_MAX_EXTEND | RCUTORTURE_RDR_RCU_1 | RCUTORTURE_RDR_RCU_2 | \
+ RCUTORTURE_RDR_MASK_1 | RCUTORTURE_RDR_MASK_2)
#define RCUTORTURE_RDR_MAX_LOOPS 0x7 /* Maximum reader extensions. */
/* Must be power of two minus one. */
#define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
@@ -108,6 +111,7 @@
torture_param(int, nocbs_toggle, 1000, "Time between toggling nocb state (ms)");
torture_param(int, read_exit_delay, 13, "Delay between read-then-exit episodes (s)");
torture_param(int, read_exit_burst, 16, "# of read-then-exit bursts per episode, zero to disable");
+torture_param(int, reader_flavor, 0x1, "Reader flavors to use, one per bit.");
torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
@@ -393,6 +397,7 @@
int slow_gps;
int no_pi_lock;
int debug_objects;
+ int start_poll_irqsoff;
const char *name;
};
@@ -581,6 +586,7 @@
.can_boost = IS_ENABLED(CONFIG_RCU_BOOST),
.extendables = RCUTORTURE_MAX_EXTEND,
.debug_objects = 1,
+ .start_poll_irqsoff = 1,
.name = "rcu"
};
@@ -641,10 +647,25 @@
static int srcu_torture_read_lock(void)
{
- if (cur_ops == &srcud_ops)
- return srcu_read_lock_nmisafe(srcu_ctlp);
- else
- return srcu_read_lock(srcu_ctlp);
+ int idx;
+ int ret = 0;
+
+ if ((reader_flavor & 0x1) || !(reader_flavor & 0x7)) {
+ idx = srcu_read_lock(srcu_ctlp);
+ WARN_ON_ONCE(idx & ~0x1);
+ ret += idx;
+ }
+ if (reader_flavor & 0x2) {
+ idx = srcu_read_lock_nmisafe(srcu_ctlp);
+ WARN_ON_ONCE(idx & ~0x1);
+ ret += idx << 1;
+ }
+ if (reader_flavor & 0x4) {
+ idx = srcu_read_lock_lite(srcu_ctlp);
+ WARN_ON_ONCE(idx & ~0x1);
+ ret += idx << 2;
+ }
+ return ret;
}
static void
@@ -668,10 +689,13 @@
static void srcu_torture_read_unlock(int idx)
{
- if (cur_ops == &srcud_ops)
- srcu_read_unlock_nmisafe(srcu_ctlp, idx);
- else
- srcu_read_unlock(srcu_ctlp, idx);
+ WARN_ON_ONCE((reader_flavor && (idx & ~reader_flavor)) || (!reader_flavor && (idx & ~0x1)));
+ if (reader_flavor & 0x4)
+ srcu_read_unlock_lite(srcu_ctlp, (idx & 0x4) >> 2);
+ if (reader_flavor & 0x2)
+ srcu_read_unlock_nmisafe(srcu_ctlp, (idx & 0x2) >> 1);
+ if ((reader_flavor & 0x1) || !(reader_flavor & 0x7))
+ srcu_read_unlock(srcu_ctlp, idx & 0x1);
}
static int torture_srcu_read_lock_held(void)
@@ -1059,8 +1083,13 @@
// At most one persisted message per boost test.
j = jiffies;
lp = READ_ONCE(last_persist);
- if (time_after(j, lp + mininterval) && cmpxchg(&last_persist, lp, j) == lp)
- pr_info("Boost inversion persisted: No QS from CPU %d\n", cpu);
+ if (time_after(j, lp + mininterval) &&
+ cmpxchg(&last_persist, lp, j) == lp) {
+ if (cpu < 0)
+ pr_info("Boost inversion persisted: QS from all CPUs\n");
+ else
+ pr_info("Boost inversion persisted: No QS from CPU %d\n", cpu);
+ }
return false; // passed on a technicality
}
VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
@@ -1695,14 +1724,22 @@
cur_ops->cond_sync_exp_full(&gp_snap_full);
break;
case RTWS_POLL_GET:
+ if (cur_ops->start_poll_irqsoff)
+ local_irq_disable();
gp_snap = cur_ops->start_gp_poll();
+ if (cur_ops->start_poll_irqsoff)
+ local_irq_enable();
while (!cur_ops->poll_gp_state(gp_snap)) {
torture_hrtimeout_jiffies(torture_random(&rand) % 16,
&rand);
}
break;
case RTWS_POLL_GET_FULL:
+ if (cur_ops->start_poll_irqsoff)
+ local_irq_disable();
cur_ops->start_gp_poll_full(&gp_snap_full);
+ if (cur_ops->start_poll_irqsoff)
+ local_irq_enable();
while (!cur_ops->poll_gp_state_full(&gp_snap_full)) {
torture_hrtimeout_jiffies(torture_random(&rand) % 16,
&rand);
@@ -1820,7 +1857,7 @@
int statesold = *readstate & ~newstate;
WARN_ON_ONCE(idxold2 < 0);
- WARN_ON_ONCE((idxold2 >> RCUTORTURE_RDR_SHIFT_2) > 1);
+ WARN_ON_ONCE(idxold2 & ~RCUTORTURE_RDR_ALLBITS);
rtrsp->rt_readstate = newstate;
/* First, put new protection in place to avoid critical-section gap. */
@@ -1835,9 +1872,9 @@
if (statesnew & RCUTORTURE_RDR_SCHED)
rcu_read_lock_sched();
if (statesnew & RCUTORTURE_RDR_RCU_1)
- idxnew1 = (cur_ops->readlock() & 0x1) << RCUTORTURE_RDR_SHIFT_1;
+ idxnew1 = (cur_ops->readlock() << RCUTORTURE_RDR_SHIFT_1) & RCUTORTURE_RDR_MASK_1;
if (statesnew & RCUTORTURE_RDR_RCU_2)
- idxnew2 = (cur_ops->readlock() & 0x1) << RCUTORTURE_RDR_SHIFT_2;
+ idxnew2 = (cur_ops->readlock() << RCUTORTURE_RDR_SHIFT_2) & RCUTORTURE_RDR_MASK_2;
/*
* Next, remove old protection, in decreasing order of strength
@@ -1857,7 +1894,7 @@
if (statesold & RCUTORTURE_RDR_RBH)
rcu_read_unlock_bh();
if (statesold & RCUTORTURE_RDR_RCU_2) {
- cur_ops->readunlock((idxold2 >> RCUTORTURE_RDR_SHIFT_2) & 0x1);
+ cur_ops->readunlock((idxold2 & RCUTORTURE_RDR_MASK_2) >> RCUTORTURE_RDR_SHIFT_2);
WARN_ON_ONCE(idxnew2 != -1);
idxold2 = 0;
}
@@ -1867,7 +1904,7 @@
lockit = !cur_ops->no_pi_lock && !statesnew && !(torture_random(trsp) & 0xffff);
if (lockit)
raw_spin_lock_irqsave(¤t->pi_lock, flags);
- cur_ops->readunlock((idxold1 >> RCUTORTURE_RDR_SHIFT_1) & 0x1);
+ cur_ops->readunlock((idxold1 & RCUTORTURE_RDR_MASK_1) >> RCUTORTURE_RDR_SHIFT_1);
WARN_ON_ONCE(idxnew1 != -1);
idxold1 = 0;
if (lockit)
@@ -1882,16 +1919,13 @@
if (idxnew1 == -1)
idxnew1 = idxold1 & RCUTORTURE_RDR_MASK_1;
WARN_ON_ONCE(idxnew1 < 0);
- if (WARN_ON_ONCE((idxnew1 >> RCUTORTURE_RDR_SHIFT_1) > 1))
- pr_info("Unexpected idxnew1 value of %#x\n", idxnew1);
if (idxnew2 == -1)
idxnew2 = idxold2 & RCUTORTURE_RDR_MASK_2;
WARN_ON_ONCE(idxnew2 < 0);
- WARN_ON_ONCE((idxnew2 >> RCUTORTURE_RDR_SHIFT_2) > 1);
*readstate = idxnew1 | idxnew2 | newstate;
WARN_ON_ONCE(*readstate < 0);
- if (WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT_2) > 1))
- pr_info("Unexpected idxnew2 value of %#x\n", idxnew2);
+ if (WARN_ON_ONCE(*readstate & ~RCUTORTURE_RDR_ALLBITS))
+ pr_info("Unexpected readstate value of %#x\n", *readstate);
}
/* Return the biggest extendables mask given current RCU and boot parameters. */
@@ -1916,7 +1950,7 @@
unsigned long preempts_irq = preempts | RCUTORTURE_RDR_IRQ;
unsigned long bhs = RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
- WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT_1);
+ WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT_1); // Can't have reader idx bits.
/* Mostly only one bit (need preemption!), sometimes lots of bits. */
if (!(randmask1 & 0x7))
mask = mask & randmask2;
@@ -2389,6 +2423,7 @@
"n_barrier_cbs=%d "
"onoff_interval=%d onoff_holdoff=%d "
"read_exit_delay=%d read_exit_burst=%d "
+ "reader_flavor=%x "
"nocbs_nthreads=%d nocbs_toggle=%d "
"test_nmis=%d\n",
torture_type, tag, nrealreaders, nfakewriters,
@@ -2401,6 +2436,7 @@
n_barrier_cbs,
onoff_interval, onoff_holdoff,
read_exit_delay, read_exit_burst,
+ reader_flavor,
nocbs_nthreads, nocbs_toggle,
test_nmis);
}
diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index 0db9db7..aacfcc9 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -75,6 +75,9 @@
torture_param(int, verbose, 0, "Enable verbose debugging printk()s");
torture_param(int, verbose_batched, 0, "Batch verbose debugging printk()s");
+// Number of seconds to extend warm-up and cool-down for multiple guest OSes
+torture_param(long, guest_os_delay, 0,
+ "Number of seconds to extend warm-up/cool-down for multiple guest OSes.");
// Wait until there are multiple CPUs before starting test.
torture_param(int, holdoff, IS_BUILTIN(CONFIG_RCU_REF_SCALE_TEST) ? 10 : 0,
"Holdoff time before test start (s)");
@@ -212,6 +215,36 @@
.name = "srcu"
};
+static void srcu_lite_ref_scale_read_section(const int nloops)
+{
+ int i;
+ int idx;
+
+ for (i = nloops; i >= 0; i--) {
+ idx = srcu_read_lock_lite(srcu_ctlp);
+ srcu_read_unlock_lite(srcu_ctlp, idx);
+ }
+}
+
+static void srcu_lite_ref_scale_delay_section(const int nloops, const int udl, const int ndl)
+{
+ int i;
+ int idx;
+
+ for (i = nloops; i >= 0; i--) {
+ idx = srcu_read_lock_lite(srcu_ctlp);
+ un_delay(udl, ndl);
+ srcu_read_unlock_lite(srcu_ctlp, idx);
+ }
+}
+
+static const struct ref_scale_ops srcu_lite_ops = {
+ .init = rcu_sync_scale_init,
+ .readsection = srcu_lite_ref_scale_read_section,
+ .delaysection = srcu_lite_ref_scale_delay_section,
+ .name = "srcu-lite"
+};
+
#ifdef CONFIG_TASKS_RCU
// Definitions for RCU Tasks ref scale testing: Empty read markers.
@@ -801,6 +834,18 @@
cur_ops->delaysection(loops, readdelay / 1000, readdelay % 1000);
}
+// Warm up cache, or, if needed run a series of rcu_scale_one_reader()
+// to allow multiple rcuscale guest OSes to collect mutually valid data.
+static void rcu_scale_warm_cool(void)
+{
+ unsigned long jdone = jiffies + (guest_os_delay > 0 ? guest_os_delay * HZ : -1);
+
+ do {
+ rcu_scale_one_reader();
+ cond_resched();
+ } while (time_before(jiffies, jdone));
+}
+
// Reader kthread. Repeatedly does empty RCU read-side
// critical section, minimizing update-side interference.
static int
@@ -829,7 +874,7 @@
goto end;
// Make sure that the CPU is affinitized appropriately during testing.
- WARN_ON_ONCE(raw_smp_processor_id() != me);
+ WARN_ON_ONCE(raw_smp_processor_id() != me % nr_cpu_ids);
WRITE_ONCE(rt->start_reader, 0);
if (!atomic_dec_return(&n_started))
@@ -957,6 +1002,7 @@
schedule_timeout_uninterruptible(1);
// Start exp readers up per experiment
+ rcu_scale_warm_cool();
for (exp = 0; exp < nruns && !torture_must_stop(); exp++) {
if (torture_must_stop())
goto end;
@@ -987,6 +1033,7 @@
result_avg[exp] = div_u64(1000 * process_durations(nreaders), nreaders * loops);
}
+ rcu_scale_warm_cool();
// Print the average of all experiments
SCALEOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n");
@@ -1082,9 +1129,10 @@
long i;
int firsterr = 0;
static const struct ref_scale_ops *scale_ops[] = {
- &rcu_ops, &srcu_ops, RCU_TRACE_OPS RCU_TASKS_OPS &refcnt_ops, &rwlock_ops,
- &rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops, &clock_ops, &jiffies_ops,
- &typesafe_ref_ops, &typesafe_lock_ops, &typesafe_seqlock_ops,
+ &rcu_ops, &srcu_ops, &srcu_lite_ops, RCU_TRACE_OPS RCU_TASKS_OPS
+ &refcnt_ops, &rwlock_ops, &rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops,
+ &clock_ops, &jiffies_ops, &typesafe_ref_ops, &typesafe_lock_ops,
+ &typesafe_seqlock_ops,
};
if (!torture_init_begin(scale_type, verbose))
diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c
index 549c033..4dcbf8a 100644
--- a/kernel/rcu/srcutiny.c
+++ b/kernel/rcu/srcutiny.c
@@ -122,8 +122,8 @@
ssp = container_of(wp, struct srcu_struct, srcu_work);
preempt_disable(); // Needed for PREEMPT_AUTO
if (ssp->srcu_gp_running || ULONG_CMP_GE(ssp->srcu_idx, READ_ONCE(ssp->srcu_idx_max))) {
- return; /* Already running or nothing to do. */
preempt_enable();
+ return; /* Already running or nothing to do. */
}
/* Remove recently arrived callbacks and wait for readers. */
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 31706e3..5e2e534 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -128,7 +128,7 @@
* Initialize the per-CPU srcu_data array, which feeds into the
* leaves of the srcu_node tree.
*/
- WARN_ON_ONCE(ARRAY_SIZE(sdp->srcu_lock_count) !=
+ BUILD_BUG_ON(ARRAY_SIZE(sdp->srcu_lock_count) !=
ARRAY_SIZE(sdp->srcu_unlock_count));
for_each_possible_cpu(cpu) {
sdp = per_cpu_ptr(ssp->sda, cpu);
@@ -187,7 +187,7 @@
/* Each pass through this loop initializes one srcu_node structure. */
srcu_for_each_node_breadth_first(ssp, snp) {
spin_lock_init(&ACCESS_PRIVATE(snp, lock));
- WARN_ON_ONCE(ARRAY_SIZE(snp->srcu_have_cbs) !=
+ BUILD_BUG_ON(ARRAY_SIZE(snp->srcu_have_cbs) !=
ARRAY_SIZE(snp->srcu_data_have_cbs));
for (i = 0; i < ARRAY_SIZE(snp->srcu_have_cbs); i++) {
snp->srcu_have_cbs[i] = SRCU_SNP_INIT_SEQ;
@@ -419,41 +419,60 @@
}
/*
- * Returns approximate total of the readers' ->srcu_lock_count[] values
- * for the rank of per-CPU counters specified by idx.
+ * Is the current or any upcoming grace period to be expedited?
*/
-static unsigned long srcu_readers_lock_idx(struct srcu_struct *ssp, int idx)
+static bool srcu_gp_is_expedited(struct srcu_struct *ssp)
{
- int cpu;
- unsigned long sum = 0;
+ struct srcu_usage *sup = ssp->srcu_sup;
- for_each_possible_cpu(cpu) {
- struct srcu_data *cpuc = per_cpu_ptr(ssp->sda, cpu);
-
- sum += atomic_long_read(&cpuc->srcu_lock_count[idx]);
- }
- return sum;
+ return ULONG_CMP_LT(READ_ONCE(sup->srcu_gp_seq), READ_ONCE(sup->srcu_gp_seq_needed_exp));
}
/*
- * Returns approximate total of the readers' ->srcu_unlock_count[] values
- * for the rank of per-CPU counters specified by idx.
+ * Computes approximate total of the readers' ->srcu_lock_count[] values
+ * for the rank of per-CPU counters specified by idx, and returns true if
+ * the caller did the proper barrier (gp), and if the count of the locks
+ * matches that of the unlocks passed in.
*/
-static unsigned long srcu_readers_unlock_idx(struct srcu_struct *ssp, int idx)
+static bool srcu_readers_lock_idx(struct srcu_struct *ssp, int idx, bool gp, unsigned long unlocks)
{
int cpu;
unsigned long mask = 0;
unsigned long sum = 0;
for_each_possible_cpu(cpu) {
- struct srcu_data *cpuc = per_cpu_ptr(ssp->sda, cpu);
+ struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu);
- sum += atomic_long_read(&cpuc->srcu_unlock_count[idx]);
+ sum += atomic_long_read(&sdp->srcu_lock_count[idx]);
if (IS_ENABLED(CONFIG_PROVE_RCU))
- mask = mask | READ_ONCE(cpuc->srcu_nmi_safety);
+ mask = mask | READ_ONCE(sdp->srcu_reader_flavor);
}
- WARN_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) && (mask & (mask >> 1)),
- "Mixed NMI-safe readers for srcu_struct at %ps.\n", ssp);
+ WARN_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) && (mask & (mask - 1)),
+ "Mixed reader flavors for srcu_struct at %ps.\n", ssp);
+ if (mask & SRCU_READ_FLAVOR_LITE && !gp)
+ return false;
+ return sum == unlocks;
+}
+
+/*
+ * Returns approximate total of the readers' ->srcu_unlock_count[] values
+ * for the rank of per-CPU counters specified by idx.
+ */
+static unsigned long srcu_readers_unlock_idx(struct srcu_struct *ssp, int idx, unsigned long *rdm)
+{
+ int cpu;
+ unsigned long mask = 0;
+ unsigned long sum = 0;
+
+ for_each_possible_cpu(cpu) {
+ struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu);
+
+ sum += atomic_long_read(&sdp->srcu_unlock_count[idx]);
+ mask = mask | READ_ONCE(sdp->srcu_reader_flavor);
+ }
+ WARN_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) && (mask & (mask - 1)),
+ "Mixed reader flavors for srcu_struct at %ps.\n", ssp);
+ *rdm = mask;
return sum;
}
@@ -463,22 +482,28 @@
*/
static bool srcu_readers_active_idx_check(struct srcu_struct *ssp, int idx)
{
+ bool did_gp;
+ unsigned long rdm;
unsigned long unlocks;
- unlocks = srcu_readers_unlock_idx(ssp, idx);
+ unlocks = srcu_readers_unlock_idx(ssp, idx, &rdm);
+ did_gp = !!(rdm & SRCU_READ_FLAVOR_LITE);
/*
* Make sure that a lock is always counted if the corresponding
* unlock is counted. Needs to be a smp_mb() as the read side may
* contain a read from a variable that is written to before the
* synchronize_srcu() in the write side. In this case smp_mb()s
- * A and B act like the store buffering pattern.
+ * A and B (or X and Y) act like the store buffering pattern.
*
- * This smp_mb() also pairs with smp_mb() C to prevent accesses
- * after the synchronize_srcu() from being executed before the
- * grace period ends.
+ * This smp_mb() also pairs with smp_mb() C (or, in the case of X,
+ * Z) to prevent accesses after the synchronize_srcu() from being
+ * executed before the grace period ends.
*/
- smp_mb(); /* A */
+ if (!did_gp)
+ smp_mb(); /* A */
+ else
+ synchronize_rcu(); /* X */
/*
* If the locks are the same as the unlocks, then there must have
@@ -536,7 +561,7 @@
* which are unlikely to be configured with an address space fully
* populated with memory, at least not anytime soon.
*/
- return srcu_readers_lock_idx(ssp, idx) == unlocks;
+ return srcu_readers_lock_idx(ssp, idx, did_gp, unlocks);
}
/**
@@ -554,12 +579,12 @@
unsigned long sum = 0;
for_each_possible_cpu(cpu) {
- struct srcu_data *cpuc = per_cpu_ptr(ssp->sda, cpu);
+ struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu);
- sum += atomic_long_read(&cpuc->srcu_lock_count[0]);
- sum += atomic_long_read(&cpuc->srcu_lock_count[1]);
- sum -= atomic_long_read(&cpuc->srcu_unlock_count[0]);
- sum -= atomic_long_read(&cpuc->srcu_unlock_count[1]);
+ sum += atomic_long_read(&sdp->srcu_lock_count[0]);
+ sum += atomic_long_read(&sdp->srcu_lock_count[1]);
+ sum -= atomic_long_read(&sdp->srcu_unlock_count[0]);
+ sum -= atomic_long_read(&sdp->srcu_unlock_count[1]);
}
return sum;
}
@@ -622,7 +647,7 @@
unsigned long jbase = SRCU_INTERVAL;
struct srcu_usage *sup = ssp->srcu_sup;
- if (ULONG_CMP_LT(READ_ONCE(sup->srcu_gp_seq), READ_ONCE(sup->srcu_gp_seq_needed_exp)))
+ if (srcu_gp_is_expedited(ssp))
jbase = 0;
if (rcu_seq_state(READ_ONCE(sup->srcu_gp_seq))) {
j = jiffies - 1;
@@ -687,28 +712,28 @@
}
EXPORT_SYMBOL_GPL(cleanup_srcu_struct);
-#ifdef CONFIG_PROVE_RCU
/*
- * Check for consistent NMI safety.
+ * Check for consistent reader flavor.
*/
-void srcu_check_nmi_safety(struct srcu_struct *ssp, bool nmi_safe)
+void __srcu_check_read_flavor(struct srcu_struct *ssp, int read_flavor)
{
- int nmi_safe_mask = 1 << nmi_safe;
- int old_nmi_safe_mask;
+ int old_read_flavor;
struct srcu_data *sdp;
- /* NMI-unsafe use in NMI is a bad sign */
- WARN_ON_ONCE(!nmi_safe && in_nmi());
+ /* NMI-unsafe use in NMI is a bad sign, as is multi-bit read_flavor values. */
+ WARN_ON_ONCE((read_flavor != SRCU_READ_FLAVOR_NMI) && in_nmi());
+ WARN_ON_ONCE(read_flavor & (read_flavor - 1));
+
sdp = raw_cpu_ptr(ssp->sda);
- old_nmi_safe_mask = READ_ONCE(sdp->srcu_nmi_safety);
- if (!old_nmi_safe_mask) {
- WRITE_ONCE(sdp->srcu_nmi_safety, nmi_safe_mask);
- return;
+ old_read_flavor = READ_ONCE(sdp->srcu_reader_flavor);
+ if (!old_read_flavor) {
+ old_read_flavor = cmpxchg(&sdp->srcu_reader_flavor, 0, read_flavor);
+ if (!old_read_flavor)
+ return;
}
- WARN_ONCE(old_nmi_safe_mask != nmi_safe_mask, "CPU %d old state %d new state %d\n", sdp->cpu, old_nmi_safe_mask, nmi_safe_mask);
+ WARN_ONCE(old_read_flavor != read_flavor, "CPU %d old state %d new state %d\n", sdp->cpu, old_read_flavor, read_flavor);
}
-EXPORT_SYMBOL_GPL(srcu_check_nmi_safety);
-#endif /* CONFIG_PROVE_RCU */
+EXPORT_SYMBOL_GPL(__srcu_check_read_flavor);
/*
* Counts the new reader in the appropriate per-CPU element of the
@@ -867,7 +892,7 @@
spin_lock_irq_rcu_node(sup);
idx = rcu_seq_state(sup->srcu_gp_seq);
WARN_ON_ONCE(idx != SRCU_STATE_SCAN2);
- if (ULONG_CMP_LT(READ_ONCE(sup->srcu_gp_seq), READ_ONCE(sup->srcu_gp_seq_needed_exp)))
+ if (srcu_gp_is_expedited(ssp))
cbdelay = 0;
WRITE_ONCE(sup->srcu_last_gp_end, ktime_get_mono_fast_ns());
@@ -1122,6 +1147,8 @@
* it stays until either (1) Compilers learn about this sort of
* control dependency or (2) Some production workload running on
* a production system is unduly delayed by this slowpath smp_mb().
+ * Except for _lite() readers, where it is inoperative, which
+ * means that it is a good thing that it is redundant.
*/
smp_mb(); /* E */ /* Pairs with B and C. */
@@ -1139,7 +1166,9 @@
}
/*
- * If SRCU is likely idle, return true, otherwise return false.
+ * If SRCU is likely idle, in other words, the next SRCU grace period
+ * should be expedited, return true, otherwise return false. Except that
+ * in the presence of _lite() readers, always return false.
*
* Note that it is OK for several current from-idle requests for a new
* grace period from idle to specify expediting because they will all end
@@ -1159,7 +1188,7 @@
* negligible when amortized over that time period, and the extra latency
* of a needlessly non-expedited grace period is similarly negligible.
*/
-static bool srcu_might_be_idle(struct srcu_struct *ssp)
+static bool srcu_should_expedite(struct srcu_struct *ssp)
{
unsigned long curseq;
unsigned long flags;
@@ -1168,6 +1197,9 @@
unsigned long tlast;
check_init_srcu_struct(ssp);
+ /* If _lite() readers, don't do unsolicited expediting. */
+ if (this_cpu_read(ssp->sda->srcu_reader_flavor) & SRCU_READ_FLAVOR_LITE)
+ return false;
/* If the local srcu_data structure has callbacks, not idle. */
sdp = raw_cpu_ptr(ssp->sda);
spin_lock_irqsave_rcu_node(sdp, flags);
@@ -1469,14 +1501,15 @@
* Implementation of these memory-ordering guarantees is similar to
* that of synchronize_rcu().
*
- * If SRCU is likely idle, expedite the first request. This semantic
- * was provided by Classic SRCU, and is relied upon by its users, so TREE
- * SRCU must also provide it. Note that detecting idleness is heuristic
- * and subject to both false positives and negatives.
+ * If SRCU is likely idle as determined by srcu_should_expedite(),
+ * expedite the first request. This semantic was provided by Classic SRCU,
+ * and is relied upon by its users, so TREE SRCU must also provide it.
+ * Note that detecting idleness is heuristic and subject to both false
+ * positives and negatives.
*/
void synchronize_srcu(struct srcu_struct *ssp)
{
- if (srcu_might_be_idle(ssp) || rcu_gp_is_expedited())
+ if (srcu_should_expedite(ssp) || rcu_gp_is_expedited())
synchronize_srcu_expedited(ssp);
else
__synchronize_srcu(ssp, true);
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 4d7ee95..59314da 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1407,7 +1407,8 @@
*/
void synchronize_rcu_tasks_rude(void)
{
- synchronize_rcu_tasks_generic(&rcu_tasks_rude);
+ if (!IS_ENABLED(CONFIG_ARCH_WANTS_NO_INSTR) || IS_ENABLED(CONFIG_FORCE_TASKS_RUDE_RCU))
+ synchronize_rcu_tasks_generic(&rcu_tasks_rude);
}
EXPORT_SYMBOL_GPL(synchronize_rcu_tasks_rude);
@@ -1549,22 +1550,7 @@
*/
u8 rcu_trc_cmpxchg_need_qs(struct task_struct *t, u8 old, u8 new)
{
- union rcu_special ret;
- union rcu_special trs_old = READ_ONCE(t->trc_reader_special);
- union rcu_special trs_new = trs_old;
-
- if (trs_old.b.need_qs != old)
- return trs_old.b.need_qs;
- trs_new.b.need_qs = new;
-
- // Although cmpxchg() appears to KCSAN to update all four bytes,
- // only the .b.need_qs byte actually changes.
- instrument_atomic_read_write(&t->trc_reader_special.b.need_qs,
- sizeof(t->trc_reader_special.b.need_qs));
- // Avoid false-positive KCSAN failures.
- ret.s = data_race(cmpxchg(&t->trc_reader_special.s, trs_old.s, trs_new.s));
-
- return ret.b.need_qs;
+ return cmpxchg(&t->trc_reader_special.b.need_qs, old, new);
}
EXPORT_SYMBOL_GPL(rcu_trc_cmpxchg_need_qs);
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index b1f883f..ff98233 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3511,7 +3511,7 @@
}
static void
-schedule_delayed_monitor_work(struct kfree_rcu_cpu *krcp)
+__schedule_delayed_monitor_work(struct kfree_rcu_cpu *krcp)
{
long delay, delay_left;
@@ -3526,6 +3526,16 @@
}
static void
+schedule_delayed_monitor_work(struct kfree_rcu_cpu *krcp)
+{
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&krcp->lock, flags);
+ __schedule_delayed_monitor_work(krcp);
+ raw_spin_unlock_irqrestore(&krcp->lock, flags);
+}
+
+static void
kvfree_rcu_drain_ready(struct kfree_rcu_cpu *krcp)
{
struct list_head bulk_ready[FREE_N_CHANNELS];
@@ -3836,7 +3846,7 @@
// Set timer to drain after KFREE_DRAIN_JIFFIES.
if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING)
- schedule_delayed_monitor_work(krcp);
+ __schedule_delayed_monitor_work(krcp);
unlock_return:
krc_this_cpu_unlock(krcp, flags);
@@ -4194,7 +4204,6 @@
struct rcu_data *rdp;
struct rcu_node *rnp;
- lockdep_assert_irqs_enabled();
local_irq_save(flags);
rdp = this_cpu_ptr(&rcu_data);
rnp = rdp->mynode;
@@ -4219,9 +4228,6 @@
* grace period has elapsed in the meantime. If the needed grace period
* is not already slated to start, notifies RCU core of the need for that
* grace period.
- *
- * Interrupts must be enabled for the case where it is necessary to awaken
- * the grace-period kthread.
*/
unsigned long start_poll_synchronize_rcu(void)
{
@@ -4242,9 +4248,6 @@
* grace period (whether normal or expedited) has elapsed in the meantime.
* If the needed grace period is not already slated to start, notifies
* RCU core of the need for that grace period.
- *
- * Interrupts must be enabled for the case where it is necessary to awaken
- * the grace-period kthread.
*/
void start_poll_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
{
@@ -5580,8 +5583,7 @@
* Complain and fall back to the compile-time values if this
* limit is exceeded.
*/
- if (rcu_fanout_leaf < 2 ||
- rcu_fanout_leaf > sizeof(unsigned long) * 8) {
+ if (rcu_fanout_leaf < 2 || rcu_fanout_leaf > BITS_PER_LONG) {
rcu_fanout_leaf = RCU_FANOUT_LEAF;
WARN_ON(1);
return;
diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
index 1686547..2605dd2 100644
--- a/kernel/rcu/tree_nocb.h
+++ b/kernel/rcu/tree_nocb.h
@@ -891,7 +891,18 @@
swait_event_interruptible_exclusive(rdp->nocb_cb_wq,
nocb_cb_wait_cond(rdp));
if (kthread_should_park()) {
- kthread_parkme();
+ /*
+ * kthread_park() must be preceded by an rcu_barrier().
+ * But yet another rcu_barrier() might have sneaked in between
+ * the barrier callback execution and the callbacks counter
+ * decrement.
+ */
+ if (rdp->nocb_cb_sleep) {
+ rcu_nocb_lock_irqsave(rdp, flags);
+ WARN_ON_ONCE(rcu_segcblist_n_cbs(&rdp->cblist));
+ rcu_nocb_unlock_irqrestore(rdp, flags);
+ kthread_parkme();
+ }
} else if (READ_ONCE(rdp->nocb_cb_sleep)) {
WARN_ON(signal_pending(current));
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("WokeEmpty"));
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 1c7cbd1..3927ea5 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -183,9 +183,9 @@
switch (blkd_state) {
case 0:
case RCU_EXP_TASKS:
- case RCU_EXP_TASKS + RCU_GP_BLKD:
+ case RCU_EXP_TASKS | RCU_GP_BLKD:
case RCU_GP_TASKS:
- case RCU_GP_TASKS + RCU_EXP_TASKS:
+ case RCU_GP_TASKS | RCU_EXP_TASKS:
/*
* Blocking neither GP, or first task blocking the normal
@@ -198,10 +198,10 @@
case RCU_EXP_BLKD:
case RCU_GP_BLKD:
- case RCU_GP_BLKD + RCU_EXP_BLKD:
- case RCU_GP_TASKS + RCU_EXP_BLKD:
- case RCU_GP_TASKS + RCU_GP_BLKD + RCU_EXP_BLKD:
- case RCU_GP_TASKS + RCU_EXP_TASKS + RCU_GP_BLKD + RCU_EXP_BLKD:
+ case RCU_GP_BLKD | RCU_EXP_BLKD:
+ case RCU_GP_TASKS | RCU_EXP_BLKD:
+ case RCU_GP_TASKS | RCU_GP_BLKD | RCU_EXP_BLKD:
+ case RCU_GP_TASKS | RCU_EXP_TASKS | RCU_GP_BLKD | RCU_EXP_BLKD:
/*
* First task arriving that blocks either GP, or first task
@@ -214,9 +214,9 @@
list_add_tail(&t->rcu_node_entry, &rnp->blkd_tasks);
break;
- case RCU_EXP_TASKS + RCU_EXP_BLKD:
- case RCU_EXP_TASKS + RCU_GP_BLKD + RCU_EXP_BLKD:
- case RCU_GP_TASKS + RCU_EXP_TASKS + RCU_EXP_BLKD:
+ case RCU_EXP_TASKS | RCU_EXP_BLKD:
+ case RCU_EXP_TASKS | RCU_GP_BLKD | RCU_EXP_BLKD:
+ case RCU_GP_TASKS | RCU_EXP_TASKS | RCU_EXP_BLKD:
/*
* Second or subsequent task blocking the expedited GP.
@@ -227,8 +227,8 @@
list_add(&t->rcu_node_entry, rnp->exp_tasks);
break;
- case RCU_GP_TASKS + RCU_GP_BLKD:
- case RCU_GP_TASKS + RCU_EXP_TASKS + RCU_GP_BLKD:
+ case RCU_GP_TASKS | RCU_GP_BLKD:
+ case RCU_GP_TASKS | RCU_EXP_TASKS | RCU_GP_BLKD:
/*
* Second or subsequent task blocking the normal GP.
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 4432db6..925fcda 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -76,36 +76,6 @@
}
EXPORT_SYMBOL_GPL(rcu_jiffies_till_stall_check);
-/**
- * rcu_gp_might_be_stalled - Is it likely that the grace period is stalled?
- *
- * Returns @true if the current grace period is sufficiently old that
- * it is reasonable to assume that it might be stalled. This can be
- * useful when deciding whether to allocate memory to enable RCU-mediated
- * freeing on the one hand or just invoking synchronize_rcu() on the other.
- * The latter is preferable when the grace period is stalled.
- *
- * Note that sampling of the .gp_start and .gp_seq fields must be done
- * carefully to avoid false positives at the beginnings and ends of
- * grace periods.
- */
-bool rcu_gp_might_be_stalled(void)
-{
- unsigned long d = rcu_jiffies_till_stall_check() / RCU_STALL_MIGHT_DIV;
- unsigned long j = jiffies;
-
- if (d < RCU_STALL_MIGHT_MIN)
- d = RCU_STALL_MIGHT_MIN;
- smp_mb(); // jiffies before .gp_seq to avoid false positives.
- if (!rcu_gp_in_progress())
- return false;
- // Long delays at this point avoids false positive, but a delay
- // of ULONG_MAX/4 jiffies voids your no-false-positive warranty.
- smp_mb(); // .gp_seq before second .gp_start
- // And ditto here.
- return !time_before(j, READ_ONCE(rcu_state.gp_start) + d);
-}
-
/* Don't do RCU CPU stall warnings during long sysrq printouts. */
void rcu_sysrq_start(void)
{
@@ -365,7 +335,7 @@
* that don't support NMI-based stack dumps. The NMI-triggered stack
* traces are more accurate because they are printed by the target CPU.
*/
-static void rcu_dump_cpu_stacks(void)
+static void rcu_dump_cpu_stacks(unsigned long gp_seq)
{
int cpu;
unsigned long flags;
@@ -373,15 +343,23 @@
rcu_for_each_leaf_node(rnp) {
printk_deferred_enter();
- raw_spin_lock_irqsave_rcu_node(rnp, flags);
- for_each_leaf_node_possible_cpu(rnp, cpu)
+ for_each_leaf_node_possible_cpu(rnp, cpu) {
+ if (gp_seq != data_race(rcu_state.gp_seq)) {
+ printk_deferred_exit();
+ pr_err("INFO: Stall ended during stack backtracing.\n");
+ return;
+ }
+ if (!(data_race(rnp->qsmask) & leaf_node_cpu_bit(rnp, cpu)))
+ continue;
+ raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu)) {
if (cpu_is_offline(cpu))
pr_err("Offline CPU %d blocking current GP.\n", cpu);
else
dump_cpu_task(cpu);
}
- raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
+ }
printk_deferred_exit();
}
}
@@ -638,7 +616,7 @@
(long)rcu_seq_current(&rcu_state.gp_seq), totqlen,
data_race(rcu_state.n_online_cpus)); // Diagnostic read
if (ndetected) {
- rcu_dump_cpu_stacks();
+ rcu_dump_cpu_stacks(gp_seq);
/* Complain about tasks blocking the grace period. */
rcu_for_each_leaf_node(rnp)
@@ -670,7 +648,7 @@
rcu_force_quiescent_state(); /* Kick them all. */
}
-static void print_cpu_stall(unsigned long gps)
+static void print_cpu_stall(unsigned long gp_seq, unsigned long gps)
{
int cpu;
unsigned long flags;
@@ -707,7 +685,7 @@
rcu_check_gp_kthread_expired_fqs_timer();
rcu_check_gp_kthread_starvation();
- rcu_dump_cpu_stacks();
+ rcu_dump_cpu_stacks(gp_seq);
raw_spin_lock_irqsave_rcu_node(rnp, flags);
/* Rewrite if needed in case of slow consoles. */
@@ -789,7 +767,8 @@
gs2 = READ_ONCE(rcu_state.gp_seq);
if (gs1 != gs2 ||
ULONG_CMP_LT(j, js) ||
- ULONG_CMP_GE(gps, js))
+ ULONG_CMP_GE(gps, js) ||
+ !rcu_seq_state(gs2))
return; /* No stall or GP completed since entering function. */
rnp = rdp->mynode;
jn = jiffies + ULONG_MAX / 2;
@@ -810,7 +789,7 @@
pr_err("INFO: %s detected stall, but suppressed full report due to a stuck CSD-lock.\n", rcu_state.name);
} else if (self_detected) {
/* We haven't checked in, so go dump stack. */
- print_cpu_stall(gps);
+ print_cpu_stall(gs2, gps);
} else {
/* They had a few time units to dump stack, so complain. */
print_other_cpu_stall(gs2, gps);
diff --git a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run-batch.sh b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run-batch.sh
index c3808c4..f87046b 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run-batch.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run-batch.sh
@@ -56,27 +56,30 @@
echo > $i/kvm-test-1-run-qemu.sh.out
export TORTURE_AFFINITY=
kvm-get-cpus-script.sh $T/cpuarray.awk $T/cpubatches.awk $T/cpustate
- cat << ' ___EOF___' >> $T/cpubatches.awk
- END {
- affinitylist = "";
- if (!gotcpus()) {
- print "echo No CPU-affinity information, so no taskset command.";
- } else if (cpu_count !~ /^[0-9][0-9]*$/) {
- print "echo " scenario ": Bogus number of CPUs (old qemu-cmd?), so no taskset command.";
- } else {
- affinitylist = nextcpus(cpu_count);
- if (!(affinitylist ~ /^[0-9,-][0-9,-]*$/))
- print "echo " scenario ": Bogus CPU-affinity information, so no taskset command.";
- else if (!dumpcpustate())
- print "echo " scenario ": Could not dump state, so no taskset command.";
- else
- print "export TORTURE_AFFINITY=" affinitylist;
+ if test -z "${TORTURE_NO_AFFINITY}"
+ then
+ cat << ' ___EOF___' >> $T/cpubatches.awk
+ END {
+ affinitylist = "";
+ if (!gotcpus()) {
+ print "echo No CPU-affinity information, so no taskset command.";
+ } else if (cpu_count !~ /^[0-9][0-9]*$/) {
+ print "echo " scenario ": Bogus number of CPUs (old qemu-cmd?), so no taskset command.";
+ } else {
+ affinitylist = nextcpus(cpu_count);
+ if (!(affinitylist ~ /^[0-9,-][0-9,-]*$/))
+ print "echo " scenario ": Bogus CPU-affinity information, so no taskset command.";
+ else if (!dumpcpustate())
+ print "echo " scenario ": Could not dump state, so no taskset command.";
+ else
+ print "export TORTURE_AFFINITY=" affinitylist;
+ }
}
- }
- ___EOF___
- cpu_count="`grep '# TORTURE_CPU_COUNT=' $i/qemu-cmd | sed -e 's/^.*=//'`"
- affinity_export="`awk -f $T/cpubatches.awk -v cpu_count="$cpu_count" -v scenario=$i < /dev/null`"
- $affinity_export
+ ___EOF___
+ cpu_count="`grep '# TORTURE_CPU_COUNT=' $i/qemu-cmd | sed -e 's/^.*=//'`"
+ affinity_export="`awk -f $T/cpubatches.awk -v cpu_count="$cpu_count" -v scenario=$i < /dev/null`"
+ $affinity_export
+ fi
kvm-test-1-run-qemu.sh $i >> $i/kvm-test-1-run-qemu.sh.out 2>&1 &
done
for i in $runfiles
diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh
index 7af73dd..42e5e85 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm.sh
@@ -42,6 +42,7 @@
TORTURE_KCONFIG_KASAN_ARG=""
TORTURE_KCONFIG_KCSAN_ARG=""
TORTURE_KMAKE_ARG=""
+TORTURE_NO_AFFINITY=""
TORTURE_QEMU_MEM=512
torture_qemu_mem_default=1
TORTURE_REMOTE=
@@ -82,6 +83,7 @@
echo " --kmake-arg kernel-make-arguments"
echo " --mac nn:nn:nn:nn:nn:nn"
echo " --memory megabytes|nnnG"
+ echo " --no-affinity"
echo " --no-initrd"
echo " --qemu-args qemu-arguments"
echo " --qemu-cmd qemu-system-..."
@@ -220,6 +222,9 @@
torture_qemu_mem_default=
shift
;;
+ --no-affinity)
+ TORTURE_NO_AFFINITY="no-affinity"
+ ;;
--no-initrd)
TORTURE_INITRD=""; export TORTURE_INITRD
;;
@@ -417,6 +422,7 @@
TORTURE_KCONFIG_KCSAN_ARG="$TORTURE_KCONFIG_KCSAN_ARG"; export TORTURE_KCONFIG_KCSAN_ARG
TORTURE_KMAKE_ARG="$TORTURE_KMAKE_ARG"; export TORTURE_KMAKE_ARG
TORTURE_MOD="$TORTURE_MOD"; export TORTURE_MOD
+TORTURE_NO_AFFINITY="$TORTURE_NO_AFFINITY"; export TORTURE_NO_AFFINITY
TORTURE_QEMU_CMD="$TORTURE_QEMU_CMD"; export TORTURE_QEMU_CMD
TORTURE_QEMU_INTERACTIVE="$TORTURE_QEMU_INTERACTIVE"; export TORTURE_QEMU_INTERACTIVE
TORTURE_QEMU_MAC="$TORTURE_QEMU_MAC"; export TORTURE_QEMU_MAC
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/CFLIST b/tools/testing/selftests/rcutorture/configs/rcu/CFLIST
index 98b6175..45f5725 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/CFLIST
+++ b/tools/testing/selftests/rcutorture/configs/rcu/CFLIST
@@ -5,6 +5,7 @@
TREE05
TREE07
TREE09
+SRCU-L
SRCU-N
SRCU-P
SRCU-T
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/SRCU-L b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-L
new file mode 100644
index 0000000..3b4fa8d
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-L
@@ -0,0 +1,10 @@
+CONFIG_RCU_TRACE=n
+CONFIG_SMP=y
+CONFIG_NR_CPUS=6
+CONFIG_HOTPLUG_CPU=y
+CONFIG_PREEMPT_NONE=y
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=n
+#CHECK#CONFIG_RCU_EXPERT=n
+CONFIG_KPROBES=n
+CONFIG_FTRACE=n
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/SRCU-L.boot b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-L.boot
new file mode 100644
index 0000000..0207b31
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-L.boot
@@ -0,0 +1,3 @@
+rcutorture.torture_type=srcu
+rcutorture.reader_flavor=0x4
+rcutorture.fwd_progress=3
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/SRCU-N.boot b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-N.boot
index ce0694f..b54cf87 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/SRCU-N.boot
+++ b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-N.boot
@@ -1,2 +1,3 @@
rcutorture.torture_type=srcu
+rcutorture.reader_flavor=0x2
rcutorture.fwd_progress=3
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE10 b/tools/testing/selftests/rcutorture/configs/rcu/TREE10
index a323d89..759ee51 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE10
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE10
@@ -1,5 +1,5 @@
CONFIG_SMP=y
-CONFIG_NR_CPUS=56
+CONFIG_NR_CPUS=74
CONFIG_PREEMPT_NONE=y
CONFIG_PREEMPT_VOLUNTARY=n
CONFIG_PREEMPT=n
