signals: Fix more rcu assumptions (7cf7db8d) · Commits · 戴 / test

1) Remove the misleading comment in __sigqueue_alloc() which claims that holding a spinlock is equivalent to rcu_read_lock(). 2) Add a rcu_read_lock/unlock around the __task_cred() access in __sigqueue_alloc() This needs to be revisited to remove the remaining users of read_lock(&tasklist_lock) but that's outside the scope of this patch. Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> LKML-Reference: <20091210004703.269843657@linutronix.de>

kernel/signal.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -218,13 +218,13 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimi
		struct user_struct *user;

		/*
		* We won't get problems with the target's UID changing under us
		* because changing it requires RCU be used, and if t != current, the
		* caller must be holding the RCU readlock (by way of a spinlock) and
		* we use RCU protection here
		* Protect access to @t credentials. This can go away when all
		* callers hold rcu read lock.
		*/
		rcu_read_lock();
		user = get_uid(__task_cred(t)->user);
		atomic_inc(&user->sigpending);
		rcu_read_unlock();

		if (override_rlimit \|\|
		atomic_read(&user->sigpending) <=

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