64 lines
2.0 KiB
Diff
64 lines
2.0 KiB
Diff
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From 0c352044556ad0d9fb79e6b6238e9c3f7646adf4 Mon Sep 17 00:00:00 2001
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From: Peter Zijlstra <peterz@infradead.org>
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Date: Fri, 7 Apr 2017 09:04:07 +0200
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Subject: [PATCH 027/365] futex: Fix small (and harmless looking)
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inconsistencies
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Upstream commit 94ffac5d847cfd790bb37b7cef1cad803743985e
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During (post-commit) review Darren spotted a few minor things. One
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(harmless AFAICT) type inconsistency and a comment that wasn't as
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clear as hoped.
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Reported-by: Darren Hart (VMWare) <dvhart@infradead.org>
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Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Reviewed-by: Darren Hart (VMware) <dvhart@infradead.org>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Thomas Gleixner <tglx@linutronix.de>
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Cc: linux-kernel@vger.kernel.org
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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---
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kernel/futex.c | 11 +++++++----
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1 file changed, 7 insertions(+), 4 deletions(-)
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diff --git a/kernel/futex.c b/kernel/futex.c
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index 551b647f6167..0b4d91bc5e7f 100644
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--- a/kernel/futex.c
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+++ b/kernel/futex.c
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@@ -1041,7 +1041,8 @@ static int attach_to_pi_state(u32 __user *uaddr, u32 uval,
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struct futex_pi_state **ps)
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{
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pid_t pid = uval & FUTEX_TID_MASK;
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- int ret, uval2;
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+ u32 uval2;
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+ int ret;
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/*
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* Userspace might have messed up non-PI and PI futexes [3]
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@@ -1457,6 +1458,11 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_
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if (ret)
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goto out_unlock;
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+ /*
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+ * This is a point of no return; once we modify the uval there is no
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+ * going back and subsequent operations must not fail.
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+ */
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+
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raw_spin_lock(&pi_state->owner->pi_lock);
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WARN_ON(list_empty(&pi_state->list));
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list_del_init(&pi_state->list);
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@@ -1468,9 +1474,6 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_
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pi_state->owner = new_owner;
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raw_spin_unlock(&new_owner->pi_lock);
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- /*
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- * We've updated the uservalue, this unlock cannot fail.
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- */
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postunlock = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q);
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out_unlock:
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--
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2.28.0
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