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SUNRPC: Optimise rpciod_up()

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Instead of taking the mutex every time we just need to increment/decrement
rpciod_users, we can optmise by using atomic_inc_not_zero and
atomic_dec_and_test.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2007-06-14 17:08:36 -04:00
parent d431a555fc
commit ab418d70e1
1 changed files with 21 additions and 28 deletions
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49
net/sunrpc/sched.c
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@ -58,7 +58,7 @@ static DECLARE_WAIT_QUEUE_HEAD(client_kill_wait);
* rpciod-related stuff
*/
static DEFINE_MUTEX(rpciod_mutex);
static unsigned int rpciod_users;
static atomic_t rpciod_users = ATOMIC_INIT(0);
struct workqueue_struct *rpciod_workqueue;
/*
@ -1047,28 +1047,27 @@ rpciod_up(void)
struct workqueue_struct *wq;
int error = 0;
if (atomic_inc_not_zero(&rpciod_users))
return 0;
mutex_lock(&rpciod_mutex);
dprintk("RPC: rpciod_up: users %u\n", rpciod_users);
rpciod_users++;
if (rpciod_workqueue)
goto out;
/*
* If there's no pid, we should be the first user.
*/
if (rpciod_users > 1)
printk(KERN_WARNING "rpciod_up: no workqueue, %u users??\n", rpciod_users);
/* Guard against races with rpciod_down() */
if (rpciod_workqueue != NULL)
goto out_ok;
/*
* Create the rpciod thread and wait for it to start.
*/
dprintk("RPC: creating workqueue rpciod\n");
error = -ENOMEM;
wq = create_workqueue("rpciod");
if (wq == NULL) {
printk(KERN_WARNING "rpciod_up: create workqueue failed, error=%d\n", error);
rpciod_users--;
if (wq == NULL)
goto out;
}
rpciod_workqueue = wq;
error = 0;
out_ok:
atomic_inc(&rpciod_users);
out:
mutex_unlock(&rpciod_mutex);
return error;
@ -1077,23 +1076,17 @@ rpciod_up(void)
void
rpciod_down(void)
{
if (!atomic_dec_and_test(&rpciod_users))
return;
mutex_lock(&rpciod_mutex);
dprintk("RPC: rpciod_down sema %u\n", rpciod_users);
if (rpciod_users) {
if (--rpciod_users)
goto out;
} else
printk(KERN_WARNING "rpciod_down: no users??\n");
dprintk("RPC: destroying workqueue rpciod\n");
if (!rpciod_workqueue) {
dprintk("RPC: rpciod_down: Nothing to do!\n");
goto out;
if (atomic_read(&rpciod_users) == 0 && rpciod_workqueue != NULL) {
rpciod_killall();
destroy_workqueue(rpciod_workqueue);
rpciod_workqueue = NULL;
}
rpciod_killall();
destroy_workqueue(rpciod_workqueue);
rpciod_workqueue = NULL;
out:
mutex_unlock(&rpciod_mutex);
}