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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Tue, 11 Dec 2018 15:10:33 +0100
Subject: [PATCH 175/353] x86/fpu: Disable preemption around local_bh_disable()
Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=c9d155d7360346edcfd997c4f8857013a8c93466
__fpu__restore_sig() restores the content of the FPU state in the CPUs
and in order to avoid concurency it disbles BH. On !RT it also disables
preemption but on RT we can get preempted in BH.
Add preempt_disable() while the FPU state is restored.
Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/x86/kernel/fpu/signal.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 86a231338bbf..e5c8d5245289 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -351,10 +351,12 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
sanitize_restored_xstate(tsk, &env, xfeatures, fx_only);
}
+ preempt_disable();
local_bh_disable();
fpu->initialized = 1;
fpu__restore(fpu);
local_bh_enable();
+ preempt_enable();
/* Failure is already handled */
return err;
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