39 lines
1.2 KiB
Diff
39 lines
1.2 KiB
Diff
From bde8ee0656280daad7779ecb33190b1eda475bc2 Mon Sep 17 00:00:00 2001
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From: David Hildenbrand <dahi@linux.vnet.ibm.com>
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Date: Mon, 11 May 2015 17:52:14 +0200
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Subject: [PATCH 09/14] futex: UP futex_atomic_cmpxchg_inatomic() relies on
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disabled preemption
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.0/patches-4.0.5-rt3.tar.xz
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Let's explicitly disable/enable preemption in the !CONFIG_SMP version
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of futex_atomic_cmpxchg_inatomic, to prepare for pagefault_disable() not
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touching preemption anymore. This is needed for this function to be
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callable from both, atomic and non-atomic context.
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Otherwise we might break mutual exclusion when relying on a get_user()/
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put_user() implementation.
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Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
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---
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include/asm-generic/futex.h | 2 ++
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1 file changed, 2 insertions(+)
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--- a/include/asm-generic/futex.h
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+++ b/include/asm-generic/futex.h
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@@ -107,6 +107,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval,
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{
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u32 val;
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+ preempt_disable();
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if (unlikely(get_user(val, uaddr) != 0))
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return -EFAULT;
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@@ -114,6 +115,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval,
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return -EFAULT;
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*uval = val;
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+ preempt_enable();
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return 0;
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}
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