This is a note to let you know that I've just added the patch titled
futex: Cleanup variable names for futex_top_waiter()
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
futex-cleanup-variable-names-for-futex_top_waiter.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Mar 4 02:09:29 PM CET 2021
From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Date: Mon, 1 Mar 2021 18:30:39 +0100
Subject: futex: Cleanup variable names for futex_top_waiter()
To: stable@xxxxxxxxxxxxxxx
Cc: Lee Jones <lee.jones@xxxxxxxxxx>, "Luis Claudio R. Goncalves" <lgoncalv@xxxxxxxxxx>
Message-ID: <YD0kv9H996Tkhg2o@xxxxxxxxxxxxxxx>
Content-Disposition: inline
From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
commit 499f5aca2cdd5e958b27e2655e7e7f82524f46b1 upstream.
futex_top_waiter() returns the top-waiter on the pi_mutex. Assinging
this to a variable 'match' totally obscures the code.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: juri.lelli@xxxxxxx
Cc: bigeasy@xxxxxxxxxxxxx
Cc: xlpang@xxxxxxxxxx
Cc: rostedt@xxxxxxxxxxx
Cc: mathieu.desnoyers@xxxxxxxxxxxx
Cc: jdesfossez@xxxxxxxxxxxx
Cc: dvhart@xxxxxxxxxxxxx
Cc: bristot@xxxxxxxxxx
Link: http://lkml.kernel.org/r/20170322104151.554710645@xxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
[bwh: Backported to 4.9: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/futex.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1352,14 +1352,14 @@ static int lookup_pi_state(u32 __user *u
union futex_key *key, struct futex_pi_state **ps,
struct task_struct **exiting)
{
- struct futex_q *match = futex_top_waiter(hb, key);
+ struct futex_q *top_waiter = futex_top_waiter(hb, key);
/*
* If there is a waiter on that futex, validate it and
* attach to the pi_state when the validation succeeds.
*/
- if (match)
- return attach_to_pi_state(uaddr, uval, match->pi_state, ps);
+ if (top_waiter)
+ return attach_to_pi_state(uaddr, uval, top_waiter->pi_state, ps);
/*
* We are the first waiter - try to look up the owner based on
@@ -1414,7 +1414,7 @@ static int futex_lock_pi_atomic(u32 __us
int set_waiters)
{
u32 uval, newval, vpid = task_pid_vnr(task);
- struct futex_q *match;
+ struct futex_q *top_waiter;
int ret;
/*
@@ -1440,9 +1440,9 @@ static int futex_lock_pi_atomic(u32 __us
* Lookup existing state first. If it exists, try to attach to
* its pi_state.
*/
- match = futex_top_waiter(hb, key);
- if (match)
- return attach_to_pi_state(uaddr, uval, match->pi_state, ps);
+ top_waiter = futex_top_waiter(hb, key);
+ if (top_waiter)
+ return attach_to_pi_state(uaddr, uval, top_waiter->pi_state, ps);
/*
* No waiter and user TID is 0. We are here because the
@@ -1532,11 +1532,11 @@ static void mark_wake_futex(struct wake_
q->lock_ptr = NULL;
}
-static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this,
+static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *top_waiter,
struct futex_hash_bucket *hb)
{
struct task_struct *new_owner;
- struct futex_pi_state *pi_state = this->pi_state;
+ struct futex_pi_state *pi_state = top_waiter->pi_state;
u32 uninitialized_var(curval), newval;
WAKE_Q(wake_q);
bool deboost;
@@ -1557,7 +1557,7 @@ static int wake_futex_pi(u32 __user *uad
/*
* When we interleave with futex_lock_pi() where it does
- * rt_mutex_timed_futex_lock(), we might observe @this futex_q waiter,
+ * rt_mutex_timed_futex_lock(), we might observe @top_waiter futex_q waiter,
* but the rt_mutex's wait_list can be empty (either still, or again,
* depending on which side we land).
*
@@ -2975,7 +2975,7 @@ static int futex_unlock_pi(u32 __user *u
u32 uninitialized_var(curval), uval, vpid = task_pid_vnr(current);
union futex_key key = FUTEX_KEY_INIT;
struct futex_hash_bucket *hb;
- struct futex_q *match;
+ struct futex_q *top_waiter;
int ret;
retry:
@@ -2999,9 +2999,9 @@ retry:
* all and we at least want to know if user space fiddled
* with the futex value instead of blindly unlocking.
*/
- match = futex_top_waiter(hb, &key);
- if (match) {
- ret = wake_futex_pi(uaddr, uval, match, hb);
+ top_waiter = futex_top_waiter(hb, &key);
+ if (top_waiter) {
+ ret = wake_futex_pi(uaddr, uval, top_waiter, hb);
/*
* In case of success wake_futex_pi dropped the hash
* bucket lock.
Patches currently in stable-queue which might be from ben@xxxxxxxxxxxxxxx are
queue-4.9/futex-cleanup-refcounting.patch
queue-4.9/futex-fix-more-put_pi_state-vs.-exit_pi_state_list-races.patch
queue-4.9/futex-futex_unlock_pi-determinism.patch
queue-4.9/futex-cleanup-variable-names-for-futex_top_waiter.patch
queue-4.9/futex-don-t-enable-irqs-unconditionally-in-put_pi_state.patch
queue-4.9/futex-fix-pi_state-owner-serialization.patch
queue-4.9/futex-pull-rt_mutex_futex_unlock-out-from-under-hb-lock.patch
