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| author | Valentin Schneider <valentin.schneider@arm.com> | 2021-07-07 20:38:31 +0200 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-07-08 15:38:10 +0200 |
| commit | 2c669ef6979c370f98d4b876e54f19613c81e075 (patch) | |
| tree | 8148f1d88d6ca6a4981aca529833cc17724de70d /arch/powerpc | |
| parent | powerpc/64e: Fix system call illegal mtmsrd instruction (diff) | |
| download | linux-2c669ef6979c370f98d4b876e54f19613c81e075.tar.xz linux-2c669ef6979c370f98d4b876e54f19613c81e075.zip | |
powerpc/preempt: Don't touch the idle task's preempt_count during hotplug
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.
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>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Bharata B Rao <bharata@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210707183831.2106509-1-valentin.schneider@arm.com
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/platforms/cell/smp.c | 3 | ||||
| -rw-r--r-- | arch/powerpc/platforms/pseries/smp.c | 3 |
2 files changed, 0 insertions, 6 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..f47429323eee 100644 --- a/arch/powerpc/platforms/pseries/smp.c +++ b/arch/powerpc/platforms/pseries/smp.c @@ -105,9 +105,6 @@ 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. |