[PATCH AUTOSEL 5.1 165/219] wil6210: drop old event after wmi_call timeout

Sasha Levin
2019-07-15T14:14:04Z

From: Ahmad Masri <amasri@codeaurora.org>

[ Upstream commit 1a276003111c0404f6bfeffe924c5a21f482428b ]

This change fixes a rare race condition of handling WMI events after
wmi_call expires.

wmi_recv_cmd immediately handles an event when reply_buf is defined and
a wmi_call is waiting for the event.
However, in case the wmi_call has already timed-out, there will be no
waiting/running wmi_call and the event will be queued in WMI queue and
will be handled later in wmi_event_handle.
Meanwhile, a new similar wmi_call for the same command and event may
be issued. In this case, when handling the queued event we got WARN_ON
printed.

Fixing this case as a valid timeout and drop the unexpected event.

Signed-off-by: Ahmad Masri <amasri@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/wireless/ath/wil6210/wmi.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/wil6210/wmi.c b/drivers/net/wireless/ath/wil6210/wmi.c
index 63116f4b62c7..de52e532c105 100644
--- a/drivers/net/wireless/ath/wil6210/wmi.c
+++ b/drivers/net/wireless/ath/wil6210/wmi.c
@@ -3211,7 +3211,18 @@ static void wmi_event_handle(struct wil6210_priv *wil,
/* check if someone waits for this event */
if (wil->reply_id && wil->reply_id == id &&
wil->reply_mid == mid) {
- WARN_ON(wil->reply_buf);
+ if (wil->reply_buf) {
+ /* event received while wmi_call is waiting
+ * with a buffer. Such event should be handled
+ * in wmi_recv_cmd function. Handling the event
+ * here means a previous wmi_call was timeout.
+ * Drop the event and do not handle it.
+ */
+ wil_err(wil,
+ "Old event (%d, %s) while wmi_call is waiting. Drop it and Continue waiting\n",
+ id, eventid2name(id));
+ return;
+ }

wmi_evt_call_handler(vif, id, evt_data,
len - sizeof(*wmi));
--
2.20.1