Commit f4985dc7 authored Jun 29, 2010 by Andrew Morton Committed by Linus Torvalds Jun 29, 2010

fs/fcntl.c:kill_fasync_rcu() fa_lock must be IRQ-safe

Fix a lockdep-splat-causing regression introduced by commit 989a2979
("fasync: RCU and fine grained locking").

kill_fasync() can be called from both process and hard-irq context, so
fa_lock must be taken with IRQs disabled.

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=16230



Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: Dominik Brodowski <linux@dominikbrodowski.net>
Tested-by: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Maciej Rutecki <maciej.rutecki@gmail.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: "David S. Miller" <davem@davemloft.net>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent fb967ecc

fs/fcntl.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -733,12 +733,14 @@ static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
		{
		while (fa) {
		struct fown_struct *fown;
		unsigned long flags;

		if (fa->magic != FASYNC_MAGIC) {
		printk(KERN_ERR "kill_fasync: bad magic number in "
		"fasync_struct!\n");
		return;
		}
		spin_lock(&fa->fa_lock);
		spin_lock_irqsave(&fa->fa_lock, flags);
		if (fa->fa_file) {
		fown = &fa->fa_file->f_owner;
		/* Don't send SIGURG to processes which have not set a
		@@ -747,7 +749,7 @@ static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
		if (!(sig == SIGURG && fown->signum == 0))
		send_sigio(fown, fa->fa_fd, band);
		}
		spin_unlock(&fa->fa_lock);
		spin_unlock_irqrestore(&fa->fa_lock, flags);
		fa = rcu_dereference(fa->fa_next);
		}
		}

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