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| author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-03-28 16:11:16 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-28 18:36:42 -0800 |
| commit | 6b3934ef52712ece50605dfc72e55d00c580831a (patch) | |
| tree | 5ec3c4f69a20880f75de6ff8d7d2f67d96328df3 /kernel/fork.c | |
| parent | 7001510d0cbf51ad202dd2d0744f54104285cbb9 (diff) | |
| download | linux-6b3934ef52712ece50605dfc72e55d00c580831a.tar.bz2 | |
[PATCH] copy_process: cleanup bad_fork_cleanup_signal
__exit_signal() does important cleanups atomically under ->siglock. It is
also called from copy_process's error path. This is not good, for example we
can't move __unhash_process() under ->siglock for that reason.
We should not mix these 2 paths, just look at ugly 'if (p->sighand)' under
'bad_fork_cleanup_sighand:' label. For copy_process() case it is sufficient
to just backout copy_signal(), nothing more.
Again, nobody can see this task yet. For CLONE_THREAD case we just decrement
signal->count, otherwise nobody can see this ->signal and we can free it
lockless.
This patch assumes it is safe to do exit_thread_group_keys() without
tasklist_lock.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 8a46ad52be8f..0aff28cdbadd 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -84,7 +84,7 @@ static kmem_cache_t *task_struct_cachep; #endif /* SLAB cache for signal_struct structures (tsk->signal) */ -kmem_cache_t *signal_cachep; +static kmem_cache_t *signal_cachep; /* SLAB cache for sighand_struct structures (tsk->sighand) */ kmem_cache_t *sighand_cachep; @@ -872,6 +872,22 @@ static inline int copy_signal(unsigned long clone_flags, struct task_struct * ts return 0; } +void __cleanup_signal(struct signal_struct *sig) +{ + exit_thread_group_keys(sig); + kmem_cache_free(signal_cachep, sig); +} + +static inline void cleanup_signal(struct task_struct *tsk) +{ + struct signal_struct *sig = tsk->signal; + + atomic_dec(&sig->live); + + if (atomic_dec_and_test(&sig->count)) + __cleanup_signal(sig); +} + static inline void copy_flags(unsigned long clone_flags, struct task_struct *p) { unsigned long new_flags = p->flags; @@ -1206,10 +1222,9 @@ bad_fork_cleanup_mm: if (p->mm) mmput(p->mm); bad_fork_cleanup_signal: - exit_signal(p); + cleanup_signal(p); bad_fork_cleanup_sighand: - if (p->sighand) - __exit_sighand(p); + __exit_sighand(p); bad_fork_cleanup_fs: exit_fs(p); /* blocking */ bad_fork_cleanup_files: |