From 3a1bb10d46ad7c43e137a2081945ee4709bb98e7 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Fri, 19 May 2023 16:57:30 +0200 Subject: [PATCH 175/204] ARM: vfp: Use vfp_lock() in vfp_sync_hwstate(). 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 --- arch/arm/vfp/vfpmodule.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) Index: linux-6.6.58-rt45/arch/arm/vfp/vfpmodule.c =================================================================== --- linux-6.6.58-rt45.orig/arch/arm/vfp/vfpmodule.c +++ linux-6.6.58-rt45/arch/arm/vfp/vfpmodule.c @@ -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 fmxr(FPEXC, fpexc); } - local_bh_enable(); - put_cpu(); + vfp_unlock(); } /* Ensure that the thread reloads the hardware VFP state on the next use. */