linux-kernel - [PATCH v4 2/5] soc: qcom: rpmh-rsc: We aren't notified of our own failure w/ NOTIFY

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Message-Id: <20200422145408.v4.2.I1927d1bca2569a27b2d04986baf285027f0818a2@changeid>
Date:   Wed, 22 Apr 2020 14:55:00 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        rafael.j.wysocki@...el.com, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     mka@...omium.org, swboyd@...omium.org, mkshah@...eaurora.org,
        evgreen@...omium.org, Douglas Anderson <dianders@...omium.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v4 2/5] soc: qcom: rpmh-rsc: We aren't notified of our own failure w/ NOTIFY_BAD

When a PM Notifier returns NOTIFY_BAD it doesn't get called with
CPU_PM_ENTER_FAILED.  It only get called for CPU_PM_ENTER_FAILED if
someone else (further down the notifier chain) returns NOTIFY_BAD.

Handle this case by taking our CPU out of the list of ones that have
entered PM.  Without this it's possible we could detect that the last
CPU went down (and we would flush) even if some CPU was alive.  That's
not good since our flushing routines currently assume they're running
on the last CPU for mutual exclusion.

Fixes: 985427f997b6 ("soc: qcom: rpmh: Invoke rpmh_flush() for dirty caches")
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---

Changes in v4:
- ("...We aren't notified of our own failure...") split out for v4.

Changes in v3: None
Changes in v2: None

 drivers/soc/qcom/rpmh-rsc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
index 3571a99fc839..e540e49fd61c 100644
--- a/drivers/soc/qcom/rpmh-rsc.c
+++ b/drivers/soc/qcom/rpmh-rsc.c
@@ -823,6 +823,10 @@ static int rpmh_rsc_cpu_pm_callback(struct notifier_block *nfb,
 		ret = NOTIFY_OK;
 
 exit:
+	if (ret == NOTIFY_BAD)
+		/* We won't be called w/ CPU_PM_ENTER_FAILED */
+		cpumask_clear_cpu(smp_processor_id(), &drv->cpus_entered_pm);
+
 	spin_unlock(&drv->pm_lock);
 	return ret;
 }
-- 
2.26.1.301.g55bc3eb7cb9-goog