cpuidle: fix fallback mechanism for suspend to idle in absence of enter_freeze

Commit 51164251f5c3 "sched / idle: Drop default_idle_call() fallback
from call_cpuidle()" made find_deepest_state() return non-negative
value and check all the states with index > 0.  Also as a result,
find_deepest_state() returns 0 even when enter_freeze callbacks are not
implemented and enter_freeze_proper() is called which ends up crashing
the kernel.

This patch updates the check for index > 0 in cpuidle_enter_freeze and
cpuidle_idle_call(when idle_should_freeze is true) to restore the
suspend-to-idle functionality in absence of enter_freeze callback.

Fixes: 51164251f5c3 "sched / idle: Drop default_idle_call() fallback from call_cpuidle()"
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 046423b0c5ca22aad3455101d3cafae7fc4dda87..f996efc56605a3d4739ae0bcac83099fd65b0751 100644 (file)
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -153,7 +153,7 @@ int cpuidle_enter_freeze(struct cpuidle_driver *drv, struct cpuidle_device *dev)
         * be frozen safely.
         */
        index = find_deepest_state(drv, dev, UINT_MAX, 0, true);
-       if (index >= 0)
+       if (index > 0)
                enter_freeze_proper(drv, dev, index);
 
        return index;

diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 34852ee70d549848d5793517677c276cdb7e98e5..30f7b6ad392088b894581c13481d58c599b5c78c 100644 (file)
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -162,7 +162,7 @@ static void cpuidle_idle_call(void)
         */
        if (idle_should_freeze()) {
                entered_state = cpuidle_enter_freeze(drv, dev);
-               if (entered_state >= 0) {
+               if (entered_state > 0) {
                        local_irq_enable();
                        goto exit_idle;
                }