[PATCH -v5 03/14] futex: Cleanup variable names for futex_top_waiter()

From: Peter Zijlstra
Date: Sat Mar 04 2017 - 06:44:15 EST


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>
---
kernel/futex.c | 30 +++++++++++++++---------------
1 file changed, 15 insertions(+), 15 deletions(-)

--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1120,14 +1120,14 @@ static int attach_to_pi_owner(u32 uval,
static int lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
union futex_key *key, struct futex_pi_state **ps)
{
- 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(uval, match->pi_state, ps);
+ if (top_waiter)
+ return attach_to_pi_state(uval, top_waiter->pi_state, ps);

/*
* We are the first waiter - try to look up the owner based on
@@ -1174,7 +1174,7 @@ static int futex_lock_pi_atomic(u32 __us
struct task_struct *task, int set_waiters)
{
u32 uval, newval, vpid = task_pid_vnr(task);
- struct futex_q *match;
+ struct futex_q *top_waiter;
int ret;

/*
@@ -1200,9 +1200,9 @@ 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(uval, match->pi_state, ps);
+ top_waiter = futex_top_waiter(hb, key);
+ if (top_waiter)
+ return attach_to_pi_state(uval, top_waiter->pi_state, ps);

/*
* No waiter and user TID is 0. We are here because the
@@ -1292,11 +1292,11 @@ 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;
DEFINE_WAKE_Q(wake_q);
bool deboost;
@@ -1317,11 +1317,11 @@ static int wake_futex_pi(u32 __user *uad

/*
* It is possible that the next waiter (the one that brought
- * this owner to the kernel) timed out and is no longer
+ * top_waiter owner to the kernel) timed out and is no longer
* waiting on the lock.
*/
if (!new_owner)
- new_owner = this->task;
+ new_owner = top_waiter->task;

/*
* We pass it to the next owner. The WAITERS bit is always
@@ -2631,7 +2631,7 @@ 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:
@@ -2655,9 +2655,9 @@ static int futex_unlock_pi(u32 __user *u
* 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.