[PATCH] taskstats_tgid_free: fix usage (093a8e8a) · Commits · 戴 / test

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>

include/linux/taskstats_kern.h

+2 −11

Original line number	Diff line number	Diff line
		@@ -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 );

kernel/exit.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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);
		}
		}

kernel/fork.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -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);
		}

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