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ARM: 9424/1: vfp: Use vfp_state_hold() in vfp_sync_hwstate().

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vfp_sync_hwstate() uses preempt_disable() followed by local_bh_disable()
to ensure that it won't get interrupted while checking the VFP state.
This harms PREEMPT_RT because softirq handling can get preempted and
local_bh_disable() synchronizes the related section with a sleeping lock
which does not work with disabled preemption.

Use the vfp_state_hold() to synchronize the access.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Sebastian Andrzej Siewior 2024-10-02 17:16:33 +01:00 committed by Russell King (Oracle)
parent f26bdbe1fa
commit b54cdbad4a
1 changed files with 3 additions and 6 deletions
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9
arch/arm/vfp/vfpmodule.c
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@ -540,11 +540,9 @@ static inline void vfp_pm_init(void) { }
*/
void vfp_sync_hwstate(struct thread_info *thread)
{
unsigned int cpu = get_cpu();
vfp_state_hold();
local_bh_disable();
if (vfp_state_in_hw(cpu, thread)) {
if (vfp_state_in_hw(raw_smp_processor_id(), thread)) {
u32 fpexc = fmrx(FPEXC);
/*
@ -555,8 +553,7 @@ void vfp_sync_hwstate(struct thread_info *thread)
fmxr(FPEXC, fpexc);
}
local_bh_enable();
put_cpu();
vfp_state_release();
}
/* Ensure that the thread reloads the hardware VFP state on the next use. */