linux-kernel - [V2 6/6] remoteproc: sysmon: Send sysmon state only for running rprocs

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Message-ID: <1653891771-17103-7-git-send-email-quic_sibis@quicinc.com>
Date:   Mon, 30 May 2022 11:52:51 +0530
From:   Sibi Sankar <quic_sibis@...cinc.com>
To:     <bjorn.andersson@...aro.org>
CC:     <agross@...nel.org>, <mathieu.poirier@...aro.org>,
        <dmitry.baryshkov@...aro.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <konrad.dybcio@...ainline.org>,
        Siddharth Gupta <sidgup@...eaurora.org>,
        Sibi Sankar <quic_sibis@...cinc.com>
Subject: [V2 6/6] remoteproc: sysmon: Send sysmon state only for running rprocs

From: Siddharth Gupta <sidgup@...eaurora.org>

When a new remoteproc boots up, send the sysmon state notification
of only running remoteprocs. Sending state of remoteprocs booting
up in parallel can cause a race between SSR clients of the remoteproc
that is booting up and the sysmon notification for the same remoteproc,
resulting in an inconsistency between which state the remoteproc that
is booting up in parallel.

For example - if remoteproc A and B crash one after the other, after
remoteproc A boots up, if the remoteproc A tries to get the state of
remoteproc B before the sysmon subdevice for B is invoked but after
the ssr subdevice of B has been invoked, clients on remoteproc A
might get confused when the sysmon notification indicates a different
state.

Signed-off-by: Siddharth Gupta <sidgup@...eaurora.org>
Signed-off-by: Sibi Sankar <quic_sibis@...cinc.com>
---
 drivers/remoteproc/qcom_sysmon.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/remoteproc/qcom_sysmon.c b/drivers/remoteproc/qcom_sysmon.c
index a9f04dd83ab6..57dde2a69b9d 100644
--- a/drivers/remoteproc/qcom_sysmon.c
+++ b/drivers/remoteproc/qcom_sysmon.c
@@ -512,10 +512,12 @@ static int sysmon_start(struct rproc_subdev *subdev)

 	mutex_lock(&sysmon_lock);
 	list_for_each_entry(target, &sysmon_list, node) {
-		if (target == sysmon)
+		mutex_lock(&target->state_lock);
+		if (target == sysmon || target->state != SSCTL_SSR_EVENT_AFTER_POWERUP) {
+			mutex_unlock(&target->state_lock);
 			continue;
+		}

-		mutex_lock(&target->state_lock);
 		event.subsys_name = target->name;
 		event.ssr_event = target->state;

-- 
2.7.4