From: Logan Gunthorpe <logang@deltatee.com>
To: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
Bjorn Helgaas <bhelgaas@google.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Logan Gunthorpe <logang@deltatee.com>
Subject: [PATCH] PCI/switchtec: Fix init_completion race condition with poll_wait()
Date: Fri, 13 Mar 2020 12:36:08 -0600 [thread overview]
Message-ID: <20200313183608.2646-1-logang@deltatee.com> (raw)
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, but we should fix it for
correctness.
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>
---
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 a823b4b8ef8a..81dc7ac01381 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);
--
2.20.1
next reply other threads:[~2020-03-13 18:36 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-13 18:36 Logan Gunthorpe [this message]
2020-03-17 0:56 ` [PATCH] PCI/switchtec: Fix init_completion race condition with poll_wait() Thomas Gleixner
2020-03-17 1:25 ` Logan Gunthorpe
2020-03-17 9:05 ` Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Logan Gunthorpe
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