[PATCH AUTOSEL 5.7 001/388] staging: wfx: fix potential deadlock in wfx_tx_flush()

Sasha Levin
2020-06-18T01:08:10Z

From: Jérôme Pouiller <jerome.pouiller@silabs.com>

[ Upstream commit a39e761aa4fefa2a8aaf549217329933b91da7c9 ]

wfx_tx_flush() wait there are no more frame in device buffer. However,
this event may never happens since wfx_tx_flush() don't forbid to
enqueue new frames.

Note that wfx_tx_flush() should only ensure that all frames currently in
hardware queues are sent. So the current code is more restrictive that
it should.

Note that wfx_tx_flush() release the lock before to return while
wfx_tx_lock_flush() keep the lock.

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200401110405.80282-31-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/staging/wfx/queue.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/staging/wfx/queue.c b/drivers/staging/wfx/queue.c
index 39d9127ce4b9..8ae23681e29b 100644
--- a/drivers/staging/wfx/queue.c
+++ b/drivers/staging/wfx/queue.c
@@ -35,6 +35,7 @@ void wfx_tx_flush(struct wfx_dev *wdev)
if (wdev->chip_frozen)
return;

+ wfx_tx_lock(wdev);
mutex_lock(&wdev->hif_cmd.lock);
ret = wait_event_timeout(wdev->hif.tx_buffers_empty,
!wdev->hif.tx_buffers_used,
@@ -47,6 +48,7 @@ void wfx_tx_flush(struct wfx_dev *wdev)
wdev->chip_frozen = 1;
}
mutex_unlock(&wdev->hif_cmd.lock);
+ wfx_tx_unlock(wdev);
}

void wfx_tx_lock_flush(struct wfx_dev *wdev)
--
2.25.1