Commit-ID: 94ffac5d847cfd790bb37b7cef1cad803743985e
Gitweb: http://git.kernel.org/tip/94ffac5d847cfd790bb37b7cef1cad803743985e
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Fri, 7 Apr 2017 09:04:07 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 14 Apr 2017 10:30:07 +0200
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@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Darren Hart (VMware) <dvhart@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/futex.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index 7ac1676..ede2f1e 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:
--
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