Messages in this thread Patch in this message | | | Date | Fri, 20 Nov 2020 12:41:47 +0100 | From | Peter Zijlstra <> | Subject | [PATCH 2/2] intel_idle: Fix intel_idle() vs tracing |
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cpuidle->enter() callbacks should not call into tracing because RCU has already been disabled. Instead of doing the broadcast thing itself, simply advertise to the cpuidle core that those states stop the timer.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- drivers/idle/intel_idle.c | 37 ++++++++++++++++++++----------------- 1 file changed, 20 insertions(+), 17 deletions(-)
--- a/drivers/idle/intel_idle.c +++ b/drivers/idle/intel_idle.c @@ -126,26 +126,9 @@ static __cpuidle int intel_idle(struct c struct cpuidle_state *state = &drv->states[index]; unsigned long eax = flg2MWAIT(state->flags); unsigned long ecx = 1; /* break on interrupt flag */ - bool tick; - - if (!static_cpu_has(X86_FEATURE_ARAT)) { - /* - * Switch over to one-shot tick broadcast if the target C-state - * is deeper than C1. - */ - if ((eax >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) { - tick = true; - tick_broadcast_enter(); - } else { - tick = false; - } - } mwait_idle_with_hints(eax, ecx); - if (!static_cpu_has(X86_FEATURE_ARAT) && tick) - tick_broadcast_exit(); - return index; } @@ -1460,6 +1443,23 @@ static bool __init intel_idle_verify_cst return true; } +static bool __init intel_idle_state_needs_timer_stop(struct cpuidle_state *state) +{ + unsigned long eax = flg2MWAIT(state->flags); + + if (boot_cpu_has(X86_FEATURE_ARAT)) + return false; + + /* + * Switch over to one-shot tick broadcast if the target C-state + * is deeper than C1. + */ + if ((eax >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + return true; + + return false; +} + static void __init intel_idle_init_cstates_icpu(struct cpuidle_driver *drv) { int cstate; @@ -1507,6 +1507,9 @@ static void __init intel_idle_init_cstat !(cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_ALWAYS_ENABLE))) drv->states[drv->state_count].flags |= CPUIDLE_FLAG_OFF; + if (intel_idle_state_needs_timer_stop(&drv->states[drv->state_count])) + drv->states[drv->state_count].flags |= CPUIDLE_FLAG_TIMER_STOP; + drv->state_count++; }
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