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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Tue, 11 Dec 2018 15:10:33 +0100
Subject: [PATCH 175/351] x86/fpu: Disable preemption around local_bh_disable()
Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=43e9f2f66d607d2d2c00cd783b48ce1fbb6b3f8e
__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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