[PATCH] Define struct pspace
Define a per-container pid space object. And create one instance of this
object, init_pspace, to define the entire pid space. Subsequent patches
will provide/use interfaces to create/destroy pid spaces.
Its a subset/rework of Eric Biederman's patch
http://lkml.org/lkml/2006/2/6/285 .
Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Andrey Savochkin <saw@sw.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/pid.c b/kernel/pid.c
index 8234bd0..89107b7 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -34,7 +34,6 @@
static kmem_cache_t *pid_cachep;
int pid_max = PID_MAX_DEFAULT;
-int last_pid;
#define RESERVED_PIDS 300
@@ -43,7 +42,12 @@
#define BITS_PER_PAGE (PAGE_SIZE*8)
#define BITS_PER_PAGE_MASK (BITS_PER_PAGE-1)
-#define mk_pid(map, off) (((map) - pidmap_array)*BITS_PER_PAGE + (off))
+
+static inline int mk_pid(struct pspace *pspace, struct pidmap *map, int off)
+{
+ return (map - pspace->pidmap)*BITS_PER_PAGE + off;
+}
+
#define find_next_offset(map, off) \
find_next_zero_bit((map)->page, BITS_PER_PAGE, off)
@@ -53,8 +57,12 @@
* value does not cause lots of bitmaps to be allocated, but
* the scheme scales to up to 4 million PIDs, runtime.
*/
-static struct pidmap pidmap_array[PIDMAP_ENTRIES] =
- { [ 0 ... PIDMAP_ENTRIES-1 ] = { ATOMIC_INIT(BITS_PER_PAGE), NULL } };
+struct pspace init_pspace = {
+ .pidmap = {
+ [ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL }
+ },
+ .last_pid = 0
+};
/*
* Note: disable interrupts while the pidmap_lock is held as an
@@ -69,40 +77,41 @@
* irq handlers that take it we can leave the interrupts enabled.
* For now it is easier to be safe than to prove it can't happen.
*/
+
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);
-static fastcall void free_pidmap(int pid)
+static fastcall void free_pidmap(struct pspace *pspace, int pid)
{
- struct pidmap *map = pidmap_array + pid / BITS_PER_PAGE;
+ struct pidmap *map = pspace->pidmap + pid / BITS_PER_PAGE;
int offset = pid & BITS_PER_PAGE_MASK;
clear_bit(offset, map->page);
atomic_inc(&map->nr_free);
}
-static int alloc_pidmap(void)
+static int alloc_pidmap(struct pspace *pspace)
{
- int i, offset, max_scan, pid, last = last_pid;
+ int i, offset, max_scan, pid, last = pspace->last_pid;
struct pidmap *map;
pid = last + 1;
if (pid >= pid_max)
pid = RESERVED_PIDS;
offset = pid & BITS_PER_PAGE_MASK;
- map = &pidmap_array[pid/BITS_PER_PAGE];
+ map = &pspace->pidmap[pid/BITS_PER_PAGE];
max_scan = (pid_max + BITS_PER_PAGE - 1)/BITS_PER_PAGE - !offset;
for (i = 0; i <= max_scan; ++i) {
if (unlikely(!map->page)) {
- unsigned long page = get_zeroed_page(GFP_KERNEL);
+ void *page = kzalloc(PAGE_SIZE, GFP_KERNEL);
/*
* Free the page if someone raced with us
* installing it:
*/
spin_lock_irq(&pidmap_lock);
if (map->page)
- free_page(page);
+ kfree(page);
else
- map->page = (void *)page;
+ map->page = page;
spin_unlock_irq(&pidmap_lock);
if (unlikely(!map->page))
break;
@@ -111,11 +120,11 @@
do {
if (!test_and_set_bit(offset, map->page)) {
atomic_dec(&map->nr_free);
- last_pid = pid;
+ pspace->last_pid = pid;
return pid;
}
offset = find_next_offset(map, offset);
- pid = mk_pid(map, offset);
+ pid = mk_pid(pspace, map, offset);
/*
* find_next_offset() found a bit, the pid from it
* is in-bounds, and if we fell back to the last
@@ -126,16 +135,16 @@
(i != max_scan || pid < last ||
!((last+1) & BITS_PER_PAGE_MASK)));
}
- if (map < &pidmap_array[(pid_max-1)/BITS_PER_PAGE]) {
+ if (map < &pspace->pidmap[(pid_max-1)/BITS_PER_PAGE]) {
++map;
offset = 0;
} else {
- map = &pidmap_array[0];
+ map = &pspace->pidmap[0];
offset = RESERVED_PIDS;
if (unlikely(last == offset))
break;
}
- pid = mk_pid(map, offset);
+ pid = mk_pid(pspace, map, offset);
}
return -1;
}
@@ -182,7 +191,7 @@
hlist_del_rcu(&pid->pid_chain);
spin_unlock_irqrestore(&pidmap_lock, flags);
- free_pidmap(pid->nr);
+ free_pidmap(&init_pspace, pid->nr);
call_rcu(&pid->rcu, delayed_put_pid);
}
@@ -196,7 +205,7 @@
if (!pid)
goto out;
- nr = alloc_pidmap();
+ nr = alloc_pidmap(&init_pspace);
if (nr < 0)
goto out_free;
@@ -363,10 +372,10 @@
void __init pidmap_init(void)
{
- pidmap_array->page = (void *)get_zeroed_page(GFP_KERNEL);
+ init_pspace.pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
/* Reserve PID 0. We never call free_pidmap(0) */
- set_bit(0, pidmap_array->page);
- atomic_dec(&pidmap_array->nr_free);
+ set_bit(0, init_pspace.pidmap[0].page);
+ atomic_dec(&init_pspace.pidmap[0].nr_free);
pid_cachep = kmem_cache_create("pid", sizeof(struct pid),
__alignof__(struct pid),
