On Thursday, January 21, 2016 11:19:29 AM Sudeep Holla wrote:
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 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()")
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
---
drivers/cpuidle/cpuidle.c | 2 +-
kernel/sched/idle.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
Hi Rafael,
Hi,
Sorry for the breakage.
I assume you prefer to retain find_deepest_state return non-negative
values, so I took this approach for fixing the bug. Do you think we
need to support enter_freeze_proper for index 0 ?
Zero is a special case on x86, so supporting enter_freeze_proper() for it
is not necessary.
If you think we can also make 0 a special case on ARM, the others should
not object to that either.