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author | Sukadev Bhattiprolu <sukadev@us.ibm.com> | 2006-10-02 02:17:24 -0700 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-02 07:57:15 -0700 |
commit | 3fbc96486459324e182717b03c50c90c880be6ec (patch) | |
tree | c2b5ccb3f64913daeb040c21652e4b421cc76bca /kernel/pid.c | |
parent | aa5a6662f93f52605b6c447ba6f7291e92f515c5 (diff) | |
download | kernel_samsung_tuna-3fbc96486459324e182717b03c50c90c880be6ec.zip kernel_samsung_tuna-3fbc96486459324e182717b03c50c90c880be6ec.tar.gz kernel_samsung_tuna-3fbc96486459324e182717b03c50c90c880be6ec.tar.bz2 |
[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>
Diffstat (limited to 'kernel/pid.c')
-rw-r--r-- | kernel/pid.c | 53 |
1 files changed, 31 insertions, 22 deletions
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 int pidhash_shift; static kmem_cache_t *pid_cachep; int pid_max = PID_MAX_DEFAULT; -int last_pid; #define RESERVED_PIDS 300 @@ -43,7 +42,12 @@ int pid_max_max = PID_MAX_LIMIT; #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 @@ int pid_max_max = PID_MAX_LIMIT; * 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 @@ static struct pidmap pidmap_array[PIDMAP_ENTRIES] = * 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 @@ static int alloc_pidmap(void) 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 @@ static int alloc_pidmap(void) (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 @@ fastcall void free_pid(struct pid *pid) 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 @@ struct pid *alloc_pid(void) if (!pid) goto out; - nr = alloc_pidmap(); + nr = alloc_pidmap(&init_pspace); if (nr < 0) goto out_free; @@ -363,10 +372,10 @@ void __init pidhash_init(void) 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), |