lib: atomic64: Initialize locks statically to fix early users
The atomic64 library uses a handful of static spin locks to implement
atomic 64-bit operations on architectures without support for atomic
64-bit instructions.
Unfortunately, the spinlocks are initialized in a pure initcall and that
is too late for the vfs namespace code which wants to use atomic64
operations before the initcall is run.
This became a problem as of commit 8823c079ba71: "vfs: Add setns support
for the mount namespace".
This leads to BUG messages such as:
BUG: spinlock bad magic on CPU#0, swapper/0/0
lock: atomic64_lock+0x240/0x400, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
do_raw_spin_lock+0x158/0x198
_raw_spin_lock_irqsave+0x4c/0x58
atomic64_add_return+0x30/0x5c
alloc_mnt_ns.clone.14+0x44/0xac
create_mnt_ns+0xc/0x54
mnt_init+0x120/0x1d4
vfs_caches_init+0xe0/0x10c
start_kernel+0x29c/0x300
coming out early on during boot when spinlock debugging is enabled.
Fix this by initializing the spinlocks statically at compile time.
Reported-and-tested-by: Vaibhav Bedia <vaibhav.bedia@ti.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/atomic64.c b/lib/atomic64.c
index 9785378..08a4f06 100644
--- a/lib/atomic64.c
+++ b/lib/atomic64.c
@@ -31,7 +31,11 @@
static union {
raw_spinlock_t lock;
char pad[L1_CACHE_BYTES];
-} atomic64_lock[NR_LOCKS] __cacheline_aligned_in_smp;
+} atomic64_lock[NR_LOCKS] __cacheline_aligned_in_smp = {
+ [0 ... (NR_LOCKS - 1)] = {
+ .lock = __RAW_SPIN_LOCK_UNLOCKED(atomic64_lock.lock),
+ },
+};
static inline raw_spinlock_t *lock_addr(const atomic64_t *v)
{
@@ -173,14 +177,3 @@
return ret;
}
EXPORT_SYMBOL(atomic64_add_unless);
-
-static int init_atomic64_lock(void)
-{
- int i;
-
- for (i = 0; i < NR_LOCKS; ++i)
- raw_spin_lock_init(&atomic64_lock[i].lock);
- return 0;
-}
-
-pure_initcall(init_atomic64_lock);
