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authorPeter Zijlstra <peterz@infradead.org>2017-04-07 09:04:07 +0200
committerIngo Molnar <mingo@kernel.org>2017-04-14 10:30:07 +0200
commit94ffac5d847cfd790bb37b7cef1cad803743985e (patch)
tree5d2af8a51d49a4d4a33f967ddd2cdf29e936294d /kernel
parent97181f9bd57405b879403763284537e27d46963d (diff)
futex: Fix small (and harmless looking) inconsistencies
During (post-commit) review Darren spotted a few minor things. One (harmless AFAICT) type inconsistency and a comment that wasn't as clear as hoped. Reported-by: Darren Hart (VMWare) <dvhart@infradead.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Darren Hart (VMware) <dvhart@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/futex.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index 7ac167683c9f..ede2f1ef8511 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1025,7 +1025,8 @@ static int attach_to_pi_state(u32 __user *uaddr, u32 uval,
struct futex_pi_state **ps)
{
pid_t pid = uval & FUTEX_TID_MASK;
- int ret, uval2;
+ u32 uval2;
+ int ret;
/*
* Userspace might have messed up non-PI and PI futexes [3]
@@ -1441,6 +1442,11 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_
if (ret)
goto out_unlock;
+ /*
+ * This is a point of no return; once we modify the uval there is no
+ * going back and subsequent operations must not fail.
+ */
+
raw_spin_lock(&pi_state->owner->pi_lock);
WARN_ON(list_empty(&pi_state->list));
list_del_init(&pi_state->list);
@@ -1452,9 +1458,6 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_
pi_state->owner = new_owner;
raw_spin_unlock(&new_owner->pi_lock);
- /*
- * We've updated the uservalue, this unlock cannot fail.
- */
postunlock = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q);
out_unlock: