Commit 13fdc9a7 authored Jul 14, 2007 by Ursula Braun Committed by David S. Miller Jul 14, 2007

[AF_IUCV]: Avoid deadlock between iucv_path_connect and tasklet.



An iucv deadlock may occur, where one CPU is spinning on the
iucv_table_lock for iucv_tasklet_fn(), while another CPU is holding
the iucv_table_lock for an iucv_path_connect() and is waiting for
the first CPU in an smp_call_function.
Solution: replace spin_lock in iucv_tasklet_fn by spin_trylock and
reschedule tasklet in case of non-granted lock.

Signed-off-by: Ursula Braun <braunu@de.ibm.com>
Acked-by: Frank Pavlic <fpavlic@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent da7de31c

net/iucv/iucv.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -1494,7 +1494,10 @@ static void iucv_tasklet_fn(unsigned long ignored)
		struct iucv_irq_list p, n;

		/* Serialize tasklet, iucv_path_sever and iucv_path_connect. */
		spin_lock(&iucv_table_lock);
		if (!spin_trylock(&iucv_table_lock)) {
		tasklet_schedule(&iucv_tasklet);
		return;
		}
		iucv_active_cpu = smp_processor_id();

		spin_lock_irq(&iucv_queue_lock);