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| author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-03-28 16:11:12 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-28 18:36:42 -0800 |
| commit | aa1757f90bea3f598b6e5d04d922a6a60200f1da (patch) | |
| tree | 4f8f3804b2595031d0b84de7086dc28375290f0d /kernel | |
| parent | 1f09f9749cdde4e69f95d62d96d2e03f50b3353c (diff) | |
| download | linux-aa1757f90bea3f598b6e5d04d922a6a60200f1da.tar.gz linux-aa1757f90bea3f598b6e5d04d922a6a60200f1da.tar.bz2 linux-aa1757f90bea3f598b6e5d04d922a6a60200f1da.zip | |
[PATCH] convert sighand_cache to use SLAB_DESTROY_BY_RCU
This patch borrows a clever Hugh's 'struct anon_vma' trick.
Without tasklist_lock held we can't trust task->sighand until we locked it
and re-checked that it is still the same.
But this means we don't need to defer 'kmem_cache_free(sighand)'. We can
return the memory to slab immediately, all we need is to be sure that
sighand->siglock can't dissapear inside rcu protected section.
To do so we need to initialize ->siglock inside ctor function,
SLAB_DESTROY_BY_RCU does the rest.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/fork.c | 21 | ||||
| -rw-r--r-- | kernel/signal.c | 2 |
2 files changed, 12 insertions, 11 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 0c32e28cdc5f..33ffb5bf0dbc 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -786,14 +786,6 @@ int unshare_files(void) EXPORT_SYMBOL(unshare_files); -void sighand_free_cb(struct rcu_head *rhp) -{ - struct sighand_struct *sp; - - sp = container_of(rhp, struct sighand_struct, rcu); - kmem_cache_free(sighand_cachep, sp); -} - static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk) { struct sighand_struct *sig; @@ -806,7 +798,6 @@ static inline int copy_sighand(unsigned long clone_flags, struct task_struct * t rcu_assign_pointer(tsk->sighand, sig); if (!sig) return -ENOMEM; - spin_lock_init(&sig->siglock); atomic_set(&sig->count, 1); memcpy(sig->action, current->sighand->action, sizeof(sig->action)); return 0; @@ -1356,11 +1347,21 @@ long do_fork(unsigned long clone_flags, #define ARCH_MIN_MMSTRUCT_ALIGN 0 #endif +static void sighand_ctor(void *data, kmem_cache_t *cachep, unsigned long flags) +{ + struct sighand_struct *sighand = data; + + if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) == + SLAB_CTOR_CONSTRUCTOR) + spin_lock_init(&sighand->siglock); +} + void __init proc_caches_init(void) { sighand_cachep = kmem_cache_create("sighand_cache", sizeof(struct sighand_struct), 0, - SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); + SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU, + sighand_ctor, NULL); signal_cachep = kmem_cache_create("signal_cache", sizeof(struct signal_struct), 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); diff --git a/kernel/signal.c b/kernel/signal.c index dc8f91bf9f89..b0b1ca9daa33 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -330,7 +330,7 @@ void __exit_sighand(struct task_struct *tsk) /* Ok, we're done with the signal handlers */ tsk->sighand = NULL; if (atomic_dec_and_test(&sighand->count)) - sighand_free(sighand); + kmem_cache_free(sighand_cachep, sighand); } void exit_sighand(struct task_struct *tsk) |