From: Ursula Braun <braunu@xxxxxxxxxx>
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@xxxxxxxxxx>
Acked-by: Frank Pavlic <fpavlic@xxxxxxxxxx>
---
net/iucv/iucv.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletion(-)
Index: net-2.6-uschi/net/iucv/iucv.c
===================================================================
--- net-2.6-uschi.orig/net/iucv/iucv.c
+++ net-2.6-uschi/net/iucv/iucv.c
@@ -1494,7 +1494,10 @@ static void iucv_tasklet_fn(unsigned lon
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);
--
-
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