Messages in this thread Patch in this message | | | From | Valentin Schneider <> | Subject | [PATCH] powerpc: preempt: Don't touch the idle task's preempt_count during hotplug | Date | Wed, 7 Jul 2021 19:38:31 +0100 |
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Powerpc currently resets a CPU's idle task preempt_count to 0 before said task starts executing the secondary startup routine (and becomes an idle task proper).
This conflicts with commit
f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled")
which initializes all of the idle tasks' preempt_count to PREEMPT_DISABLED during smp_init(). Note that this was superfluous before said commit, as back then the hotplug machinery would invoke init_idle() via idle_thread_get(), which would have already reset the CPU's idle task's preempt_count to PREEMPT_ENABLED.
Get rid of this preempt_count write.
Cc: Guenter Roeck <linux@roeck-us.net> Fixes: f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled") Reported-by: Bharata B Rao <bharata@linux.ibm.com> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> --- arch/powerpc/platforms/cell/smp.c | 3 --- arch/powerpc/platforms/pseries/smp.c | 5 +---- 2 files changed, 1 insertion(+), 7 deletions(-)
diff --git a/arch/powerpc/platforms/cell/smp.c b/arch/powerpc/platforms/cell/smp.c index c855a0aeb49c..d7ab868aab54 100644 --- a/arch/powerpc/platforms/cell/smp.c +++ b/arch/powerpc/platforms/cell/smp.c @@ -78,9 +78,6 @@ static inline int smp_startup_cpu(unsigned int lcpu) pcpu = get_hard_smp_processor_id(lcpu); - /* Fixup atomic count: it exited inside IRQ handler. */ - task_thread_info(paca_ptrs[lcpu]->__current)->preempt_count = 0; - /* * If the RTAS start-cpu token does not exist then presume the * cpu is already spinning. diff --git a/arch/powerpc/platforms/pseries/smp.c b/arch/powerpc/platforms/pseries/smp.c index 096629f54576..7ebf3382816a 100644 --- a/arch/powerpc/platforms/pseries/smp.c +++ b/arch/powerpc/platforms/pseries/smp.c @@ -105,10 +105,7 @@ static inline int smp_startup_cpu(unsigned int lcpu) return 1; } - /* Fixup atomic count: it exited inside IRQ handler. */ - task_thread_info(paca_ptrs[lcpu]->__current)->preempt_count = 0; - - /* + /* * If the RTAS start-cpu token does not exist then presume the * cpu is already spinning. */ -- 2.25.1
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