rwsem: smaller wrappers around rwsem_down_failed_common

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>

1 files changed, 10 insertions, 15 deletions

diff --git a/lib/rwsem.c b/lib/rwsem.c
index 318d435dcebb..f236d7cd5cf3 100644
--- a/lib/rwsem.c
+++ b/lib/rwsem.c
@@ -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);
 }
 
 /*