| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.10 09/89] cpuidle / menu: Return (-1) if there are no suitable states | Date | Fri, 31 Jul 2015 12:40:51 -0700 |
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3.10-stable review patch. If anyone has any objections, please let me know.
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From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
commit 3836785a1bdcd6706c68ad46bf53adc0b057b310 upstream.
If there is a PM QoS latency limit and all of the sufficiently shallow C-states are disabled, the cpuidle menu governor returns 0 which on some systems is CPUIDLE_DRIVER_STATE_START and shouldn't be returned if that C-state has been disabled.
Fix the issue by modifying the menu governor to return (-1) in such situations.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> [shilpab: Backport to 3.10.y - adjust context - add a check if 'next_state' is less than 0 in 'cpuidle_idle_call()', this ensures that we exit 'cpuidle_idle_call()' if governor->select() returns negative value] Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/cpuidle/cpuidle.c | 3 +++ drivers/cpuidle/governors/menu.c | 2 +- 2 files changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -135,6 +135,9 @@ int cpuidle_idle_call(void) /* ask the governor for the next state */ next_state = cpuidle_curr_governor->select(drv, dev); + if (next_state < 0) + return -EBUSY; + if (need_resched()) { dev->last_residency = 0; /* give the governor an opportunity to reflect on the outcome */ --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -269,7 +269,7 @@ static int menu_select(struct cpuidle_dr data->needs_update = 0; } - data->last_state_idx = 0; + data->last_state_idx = CPUIDLE_DRIVER_STATE_START - 1; data->exit_us = 0; /* Special case when user has set very strict latency requirement */
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