rwsem: smaller wrappers around rwsem_down_failed_common
Michel Lespinasse [Tue, 10 Aug 2010 00:21:20 +0000 (17:21 -0700)]
More code can be pushed from rwsem_down_read_failed and
rwsem_down_write_failed into rwsem_down_failed_common.

Following change adding down_read_critical infrastructure support also
enjoys having flags available in a register rather than having to fish it
out in the struct rwsem_waiter...

Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Mike Waychison <mikew@google.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/rwsem.c

index 318d435..f236d7c 100644 (file)
@@ -171,8 +171,9 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wake_type)
  */
 static struct rw_semaphore __sched *
 rwsem_down_failed_common(struct rw_semaphore *sem,
-                       struct rwsem_waiter *waiter, signed long adjustment)
+                        unsigned int flags, signed long adjustment)
 {
+       struct rwsem_waiter waiter;
        struct task_struct *tsk = current;
        signed long count;
 
@@ -180,12 +181,13 @@ rwsem_down_failed_common(struct rw_semaphore *sem,
 
        /* set up my own style of waitqueue */
        spin_lock_irq(&sem->wait_lock);
-       waiter->task = tsk;
+       waiter.task = tsk;
+       waiter.flags = flags;
        get_task_struct(tsk);
 
        if (list_empty(&sem->wait_list))
                adjustment += RWSEM_WAITING_BIAS;
-       list_add_tail(&waiter->list, &sem->wait_list);
+       list_add_tail(&waiter.list, &sem->wait_list);
 
        /* we're now waiting on the lock, but no longer actively locking */
        count = rwsem_atomic_update(adjustment, sem);
@@ -206,7 +208,7 @@ rwsem_down_failed_common(struct rw_semaphore *sem,
 
        /* wait to be given the lock */
        for (;;) {
-               if (!waiter->task)
+               if (!waiter.task)
                        break;
                schedule();
                set_task_state(tsk, TASK_UNINTERRUPTIBLE);
@@ -223,11 +225,8 @@ rwsem_down_failed_common(struct rw_semaphore *sem,
 asmregparm struct rw_semaphore __sched *
 rwsem_down_read_failed(struct rw_semaphore *sem)
 {
-       struct rwsem_waiter waiter;
-
-       waiter.flags = RWSEM_WAITING_FOR_READ;
-       rwsem_down_failed_common(sem, &waiter, -RWSEM_ACTIVE_READ_BIAS);
-       return sem;
+       return rwsem_down_failed_common(sem, RWSEM_WAITING_FOR_READ,
+                                       -RWSEM_ACTIVE_READ_BIAS);
 }
 
 /*
@@ -236,12 +235,8 @@ rwsem_down_read_failed(struct rw_semaphore *sem)
 asmregparm struct rw_semaphore __sched *
 rwsem_down_write_failed(struct rw_semaphore *sem)
 {
-       struct rwsem_waiter waiter;
-
-       waiter.flags = RWSEM_WAITING_FOR_WRITE;
-       rwsem_down_failed_common(sem, &waiter, -RWSEM_ACTIVE_WRITE_BIAS);
-
-       return sem;
+       return rwsem_down_failed_common(sem, RWSEM_WAITING_FOR_WRITE,
+                                       -RWSEM_ACTIVE_WRITE_BIAS);
 }
 
 /*