Re: [PATCH v5 1/4] futex: Misc cleanups

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Thu, Jan 02, 2014 at 07:05:17AM -0800, Davidlohr Bueso wrote:
> From: Jason Low <jason.low2@hp.com>
> 
> - Remove unnecessary head variables.
> - Delete unused parameter in queue_unlock().
> 
> Cc: Ingo Molnar <mingo@kernel.org>
> Reviewed-by: Darren Hart <dvhart@linux.intel.com>
> Acked-by: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Jeff Mahoney <jeffm@suse.com>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Scott Norton <scott.norton@hp.com>
> Cc: Tom Vaden <tom.vaden@hp.com>
> Cc: Aswin Chandramouleeswaran <aswin@hp.com>
> Cc: Waiman Long <Waiman.Long@hp.com>
> Signed-off-by: Jason Low <jason.low2@hp.com>
> Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

> ---
>  kernel/futex.c | 39 ++++++++++++---------------------------
>  1 file changed, 12 insertions(+), 27 deletions(-)
> 
> diff --git a/kernel/futex.c b/kernel/futex.c
> index f6ff019..085f5fa 100644
> --- a/kernel/futex.c
> +++ b/kernel/futex.c
> @@ -598,13 +598,10 @@ lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
>  {
>  	struct futex_pi_state *pi_state = NULL;
>  	struct futex_q *this, *next;
> -	struct plist_head *head;
>  	struct task_struct *p;
>  	pid_t pid = uval & FUTEX_TID_MASK;
> 
> -	head = &hb->chain;
> -
> -	plist_for_each_entry_safe(this, next, head, list) {
> +	plist_for_each_entry_safe(this, next, &hb->chain, list) {
>  		if (match_futex(&this->key, key)) {
>  			/*
>  			 * Another waiter already exists - bump up
> @@ -986,7 +983,6 @@ futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset)
>  {
>  	struct futex_hash_bucket *hb;
>  	struct futex_q *this, *next;
> -	struct plist_head *head;
>  	union futex_key key = FUTEX_KEY_INIT;
>  	int ret;
> 
> @@ -999,9 +995,8 @@ futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset)
> 
>  	hb = hash_futex(&key);
>  	spin_lock(&hb->lock);
> -	head = &hb->chain;
> 
> -	plist_for_each_entry_safe(this, next, head, list) {
> +	plist_for_each_entry_safe(this, next, &hb->chain, list) {
>  		if (match_futex (&this->key, &key)) {
>  			if (this->pi_state || this->rt_waiter) {
>  				ret = -EINVAL;
> @@ -1034,7 +1029,6 @@ futex_wake_op(u32 __user *uaddr1, unsigned int flags, u32 __user *uaddr2,
>  {
>  	union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT;
>  	struct futex_hash_bucket *hb1, *hb2;
> -	struct plist_head *head;
>  	struct futex_q *this, *next;
>  	int ret, op_ret;
> 
> @@ -1082,9 +1076,7 @@ retry_private:
>  		goto retry;
>  	}
> 
> -	head = &hb1->chain;
> -
> -	plist_for_each_entry_safe(this, next, head, list) {
> +	plist_for_each_entry_safe(this, next, &hb1->chain, list) {
>  		if (match_futex (&this->key, &key1)) {
>  			if (this->pi_state || this->rt_waiter) {
>  				ret = -EINVAL;
> @@ -1097,10 +1089,8 @@ retry_private:
>  	}
> 
>  	if (op_ret > 0) {
> -		head = &hb2->chain;
> -
>  		op_ret = 0;
> -		plist_for_each_entry_safe(this, next, head, list) {
> +		plist_for_each_entry_safe(this, next, &hb2->chain, list) {
>  			if (match_futex (&this->key, &key2)) {
>  				if (this->pi_state || this->rt_waiter) {
>  					ret = -EINVAL;
> @@ -1270,7 +1260,6 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags,
>  	int drop_count = 0, task_count = 0, ret;
>  	struct futex_pi_state *pi_state = NULL;
>  	struct futex_hash_bucket *hb1, *hb2;
> -	struct plist_head *head1;
>  	struct futex_q *this, *next;
>  	u32 curval2;
> 
> @@ -1393,8 +1382,7 @@ retry_private:
>  		}
>  	}
> 
> -	head1 = &hb1->chain;
> -	plist_for_each_entry_safe(this, next, head1, list) {
> +	plist_for_each_entry_safe(this, next, &hb1->chain, list) {
>  		if (task_count - nr_wake >= nr_requeue)
>  			break;
> 
> @@ -1494,7 +1482,7 @@ static inline struct futex_hash_bucket *queue_lock(struct futex_q *q)
>  }
> 
>  static inline void
> -queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb)
> +queue_unlock(struct futex_hash_bucket *hb)
>  	__releases(&hb->lock)
>  {
>  	spin_unlock(&hb->lock);
> @@ -1867,7 +1855,7 @@ retry_private:
>  	ret = get_futex_value_locked(&uval, uaddr);
> 
>  	if (ret) {
> -		queue_unlock(q, *hb);
> +		queue_unlock(*hb);
> 
>  		ret = get_user(uval, uaddr);
>  		if (ret)
> @@ -1881,7 +1869,7 @@ retry_private:
>  	}
> 
>  	if (uval != val) {
> -		queue_unlock(q, *hb);
> +		queue_unlock(*hb);
>  		ret = -EWOULDBLOCK;
>  	}
> 
> @@ -2029,7 +2017,7 @@ retry_private:
>  			 * Task is exiting and we just wait for the
>  			 * exit to complete.
>  			 */
> -			queue_unlock(&q, hb);
> +			queue_unlock(hb);
>  			put_futex_key(&q.key);
>  			cond_resched();
>  			goto retry;
> @@ -2081,7 +2069,7 @@ retry_private:
>  	goto out_put_key;
> 
>  out_unlock_put_key:
> -	queue_unlock(&q, hb);
> +	queue_unlock(hb);
> 
>  out_put_key:
>  	put_futex_key(&q.key);
> @@ -2091,7 +2079,7 @@ out:
>  	return ret != -EINTR ? ret : -ERESTARTNOINTR;
> 
>  uaddr_faulted:
> -	queue_unlock(&q, hb);
> +	queue_unlock(hb);
> 
>  	ret = fault_in_user_writeable(uaddr);
>  	if (ret)
> @@ -2113,7 +2101,6 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags)
>  {
>  	struct futex_hash_bucket *hb;
>  	struct futex_q *this, *next;
> -	struct plist_head *head;
>  	union futex_key key = FUTEX_KEY_INIT;
>  	u32 uval, vpid = task_pid_vnr(current);
>  	int ret;
> @@ -2153,9 +2140,7 @@ retry:
>  	 * Ok, other tasks may need to be woken up - check waiters
>  	 * and do the wakeup if necessary:
>  	 */
> -	head = &hb->chain;
> -
> -	plist_for_each_entry_safe(this, next, head, list) {
> +	plist_for_each_entry_safe(this, next, &hb->chain, list) {
>  		if (!match_futex (&this->key, &key))
>  			continue;
>  		ret = wake_futex_pi(uaddr, uval, this);
> -- 
> 1.8.1.4
>