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[AF_IUCV]: Avoid deadlock between iucv_path_connect and tasklet.

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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>
This commit is contained in:
Ursula Braun 2007-07-14 19:03:41 -07:00 committed by David S. Miller
parent da7de31cc5
commit 13fdc9a74d
1 changed files with 4 additions and 1 deletions
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5
net/iucv/iucv.c
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@ -1494,7 +1494,10 @@ static void iucv_tasklet_fn(unsigned long ignored)
struct iucv_irq_list *p, *n; struct iucv_irq_list *p, *n;
/* Serialize tasklet, iucv_path_sever and iucv_path_connect. */ /* 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(); iucv_active_cpu = smp_processor_id();
spin_lock_irq(&iucv_queue_lock); spin_lock_irq(&iucv_queue_lock);