linux-kernel - [PATCH] opp: Prevent memory leak in dev_pm_opp_attach

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Message-Id: <1cadaccf3728ce84d5d0af50a48ce8caaa29eb53.1598853505.git.viresh.kumar@linaro.org>
Date:   Mon, 31 Aug 2020 11:28:28 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>,
        Stephan Gerhold <stephan@...hold.net>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] opp: Prevent memory leak in dev_pm_opp_attach_genpd()

If dev_pm_opp_attach_genpd() is called multiple times (once for each CPU
sharing the table), then it would result in unwanted behavior like
memory leak, attaching the domain multiple times, etc.

Handle that by checking and returning earlier if the domains are already
attached. Now that dev_pm_opp_detach_genpd() can get called multiple
times as well, we need to protect that too.

Note that the virtual device pointers aren't returned in this case, as
they may become unavailable to some callers during the middle of the
operation.

Reported-by: Stephan Gerhold <stephan@...hold.net>
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/opp/core.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 000d0fcb4680..e65174725a4d 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1960,6 +1960,9 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
 {
 	int index;
 
+	if (!opp_table->genpd_virt_devs)
+		return;
+
 	for (index = 0; index < opp_table->required_opp_count; index++) {
 		if (!opp_table->genpd_virt_devs[index])
 			continue;
@@ -2006,6 +2009,9 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
 	if (IS_ERR(opp_table))
 		return opp_table;
 
+	if (opp_table->genpd_virt_devs)
+		return opp_table;
+
 	/*
 	 * If the genpd's OPP table isn't already initialized, parsing of the
 	 * required-opps fail for dev. We should retry this after genpd's OPP
-- 
2.25.0.rc1.19.g042ed3e048af