linux-kernel - [PATCH 2/2] soc: qcom: aoss: qmp_send() can't handle interruptions so stop pretending

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Date:   Wed,  5 Aug 2020 09:16:11 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     swboyd@...omium.org, Alex Elder <elder@...aro.org>,
        mka@...omium.org, Douglas Anderson <dianders@...omium.org>,
        Andy Gross <agross@...nel.org>, Vinod Koul <vkoul@...nel.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] soc: qcom: aoss: qmp_send() can't handle interruptions so stop pretending

The function qmp_send() called wait_event_interruptible_timeout() to
wait for its interrupt.  However, this function did not check for
-ERESTARTSYS and assumed that any non-zero return value meant that the
event happened.

While we could try to figure out how to handle interruptions by
figuring out how to cancel and/or undo our transfer in a race-free way
and then communicating this status back to all of our callers, that
seems like a whole lot of complexity.  As I understand it the transfer
should happen rather quickly and if we're really hitting the 1 second
timeout we're in deep doggy doodoo anyway.  Let's just use the
non-interruptible version of the function and call it good enough.

Found by code inspection.  No known test cases expose the problem
described here.

Fixes: 2209481409b7 ("soc: qcom: Add AOSS QMP driver")
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---

 drivers/soc/qcom/qcom_aoss.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/qcom/qcom_aoss.c b/drivers/soc/qcom/qcom_aoss.c
index 818cdf74a267..897f9f1c33ba 100644
--- a/drivers/soc/qcom/qcom_aoss.c
+++ b/drivers/soc/qcom/qcom_aoss.c
@@ -257,8 +257,8 @@ static int qmp_send(struct qmp *qmp, const void *data, size_t len, bool noirq)
 		time_left = readx_poll_timeout_atomic(qmp_message_empty, qmp,
 						      is_empty, is_empty, 1U, 1000000U);
 	else
-		time_left = wait_event_interruptible_timeout(qmp->event,
-							     qmp_message_empty(qmp), HZ);
+		time_left = wait_event_timeout(qmp->event, qmp_message_empty(qmp), HZ);
+
 	if (!time_left) {
 		dev_err(qmp->dev, "ucore did not ack channel\n");
 		ret = -ETIMEDOUT;
-- 
2.28.0.163.g6104cc2f0b6-goog