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ARM: vfp: Use vfp_lock() in vfp_sync_hwstate().

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BugLink: https://bugs.launchpad.net/bugs/2060704

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_lock() to synchronize the access.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Kevin Becker <kevin.becker@canonical.com>
This commit is contained in:
Sebastian Andrzej Siewior
2023-05-19 16:57:30 +02:00
committed by Kevin Becker
parent ea8c2fd90b
commit 6fee72ac5f
1 changed files with 3 additions and 6 deletions
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arch/arm/vfp/vfpmodule.c
+3 -6
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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_lock();
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_unlock();
}
/* Ensure that the thread reloads the hardware VFP state on the next use. */