From: Logan Gunthorpe logang@deltatee.com
[ 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() init_completion(&s->comp) init_waitqueue_head(&s->comp.wait)
To my knowledge, no one has hit this bug.
Fix this by using reinit_completion() instead of init_completion() in mrpc_queue_cmd().
Fixes: 080b47def5e5 ("MicroSemi Switchtec management interface driver")
Reported-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Signed-off-by: Logan Gunthorpe logang@deltatee.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Acked-by: Bjorn Helgaas bhelgaas@google.com Link: https://lkml.kernel.org/r/20200313183608.2646-1-logang@deltatee.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 9c3ad09d30222..fb4602d44eb10 100644 --- a/drivers/pci/switch/switchtec.c +++ b/drivers/pci/switch/switchtec.c @@ -175,7 +175,7 @@ static int mrpc_queue_cmd(struct switchtec_user *stuser) kref_get(&stuser->kref); 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);
mrpc_cmd_submit(stdev);