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Message-ID: <20171226072626.GA4153@gaurav.jindal> Date: Tue, 26 Dec 2017 12:56:26 +0530 From: gaurav jindal <gauravjindal1104@...il.com> To: rjw@...ysocki.net, daniel.lezcano@...aro.org Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org Subject: [PATCH]cpuidle: preventive check in cpuidle_select against crash When selecting the idle state using cpuidle_select, there is no check on cpuidle_curr_governor. In cpuidle_switch_governor, cpuidle_currr_governor can be set to NULL to specify "disabled". Since cpuidle_select cannot return negative value, it has to return 0 in case of error. Printing logs and returning can help in debugging and preventing possible kernel crash scenarios. Signed-off-by: Gaurav Jindal<gauravjindal1104@...il.com> --- diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 68a1682..bf08e3a 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -268,6 +268,19 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, */ int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) { + + /* Since negative return is not allowed + * we have to return 0 even if the + * framework cannot select the idle state + */ + if (!cpuidle_curr_governor) { + pr_err("idle governor is disabled\n"); + return 0; + } + if (!cpuidle_curr_governor->select) { + pr_err("idle governor select is NULL\n"); + return 0; + } return cpuidle_curr_governor->select(drv, dev); }
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