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[PATCH] taskstats_tgid_free: fix usage 

taskstats_tgid_free() is called on copy_process's error path. This is wrong.

	IF (clone_flags & CLONE_THREAD)
		We should not clear ->signal->taskstats, current uses it,
		it probably has a valid accumulated info.
	ELSE
		taskstats_tgid_init() set ->signal->taskstats = NULL,
		there is nothing to free.

Move the callsite to __exit_signal(). We don't need any locking, entire
thread group is exiting, nobody should have a reference to soon to be
released ->signal.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Shailabh Nagar <nagar@watson.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Jay Lan <jlan@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Oleg Nesterov 2006-10-28 10:38:51 -07:00 committed by Linus Torvalds
parent 05d5bcd60e
commit 093a8e8aec
3 changed files with 3 additions and 12 deletions
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13
include/linux/taskstats_kern.h
View File

@ -49,17 +49,8 @@ static inline void taskstats_tgid_alloc(struct signal_struct *sig)
static inline void taskstats_tgid_free(struct signal_struct *sig)
{
struct taskstats *stats = NULL;
unsigned long flags;
spin_lock_irqsave(&sig->stats_lock, flags);
if (sig->stats) {
stats = sig->stats;
sig->stats = NULL;
}
spin_unlock_irqrestore(&sig->stats_lock, flags);
if (stats)
kmem_cache_free(taskstats_cache, stats);
if (sig->stats)
kmem_cache_free(taskstats_cache, sig->stats);
}
extern void taskstats_exit_alloc(struct taskstats **, unsigned int *);

1
kernel/exit.c
View File

@ -128,6 +128,7 @@ static void __exit_signal(struct task_struct *tsk)
flush_sigqueue(&tsk->pending);
if (sig) {
flush_sigqueue(&sig->shared_pending);
taskstats_tgid_free(sig);
__cleanup_signal(sig);
}
}

1
kernel/fork.c
View File

@ -897,7 +897,6 @@ static inline int copy_signal(unsigned long clone_flags, struct task_struct * ts
void __cleanup_signal(struct signal_struct *sig)
{
exit_thread_group_keys(sig);
taskstats_tgid_free(sig);
kmem_cache_free(signal_cachep, sig);
}