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* [PATCH AUTOSEL 4.19 13/32] PCI/switchtec: Fix init_completion race condition with poll_wait()
       [not found] <>
@ 2020-04-10  3:49 ` Sasha Levin
  0 siblings, 0 replies; only message in thread
From: Sasha Levin @ 2020-04-10  3:49 UTC (permalink / raw)
  To: linux-kernel, stable
  Cc: Logan Gunthorpe, Sebastian Andrzej Siewior, Thomas Gleixner,
	Peter Zijlstra, Bjorn Helgaas, Sasha Levin, linux-pci

From: Logan Gunthorpe <>

[ Upstream commit efbdc769601f4d50018bf7ca50fc9f7c67392ece ]

The call to init_completion() in mrpc_queue_cmd() can theoretically
race with the call to poll_wait() in switchtec_dev_poll().

  poll()			write()
    switchtec_dev_poll()   	  switchtec_dev_write()
      poll_wait(&s->comp.wait);      mrpc_queue_cmd()

To my knowledge, no one has hit this bug.

Fix this by using reinit_completion() instead of init_completion() in

Fixes: 080b47def5e5 ("MicroSemi Switchtec management interface driver")

Reported-by: Sebastian Andrzej Siewior <>
Signed-off-by: Logan Gunthorpe <>
Signed-off-by: Thomas Gleixner <>
Signed-off-by: Peter Zijlstra (Intel) <>
Acked-by: Bjorn Helgaas <>
Signed-off-by: Sasha Levin <>
 drivers/pci/switch/switchtec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c
index 43431816412c1..291c0074ad6f4 100644
--- a/drivers/pci/switch/switchtec.c
+++ b/drivers/pci/switch/switchtec.c
@@ -147,7 +147,7 @@ static int mrpc_queue_cmd(struct switchtec_user *stuser)
 	stuser->read_len = sizeof(stuser->data);
 	stuser_set_state(stuser, MRPC_QUEUED);
-	init_completion(&stuser->comp);
+	reinit_completion(&stuser->comp);
 	list_add_tail(&stuser->list, &stdev->mrpc_queue);

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2020-04-10  3:49 ` [PATCH AUTOSEL 4.19 13/32] PCI/switchtec: Fix init_completion race condition with poll_wait() Sasha Levin

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