From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Logan Gunthorpe <logang@deltatee.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Bjorn Helgaas <bhelgaas@google.com>,
Sasha Levin <sashal@kernel.org>,
linux-pci@vger.kernel.org
Subject: [PATCH AUTOSEL 5.5 29/56] PCI/switchtec: Fix init_completion race condition with poll_wait()
Date: Thu, 9 Apr 2020 23:47:33 -0400 [thread overview]
Message-ID: <20200410034800.8381-29-sashal@kernel.org> (raw)
In-Reply-To: <20200410034800.8381-1-sashal@kernel.org>
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);
--
2.20.1
parent reply other threads:[~2020-04-10 3:59 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20200410034800.8381-1-sashal@kernel.org>]
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