locking/rwsem: Get rid of __down_write_nested()

This is no longer used anywhere and all callers (__down_write()) use
0 as a subclass. Ditch __down_write_nested() to make the code easier
to follow.

This shouldn't introduce any functional change.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Signed-off-by: Jason Low <jason.low2@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: linux-xtensa@linux-xtensa.org
Cc: sparclinux@vger.kernel.org
Link: http://lkml.kernel.org/r/1460041951-22347-2-git-send-email-mhocko@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/s390/include/asm/rwsem.h

@@ -90,7 +90,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
 /*
  * lock for writing
  */
-static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
+static inline void __down_write(struct rw_semaphore *sem)
 {
 	signed long old, new, tmp;
 
@@ -108,11 +108,6 @@ static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
 		rwsem_down_write_failed(sem);
 }
 
-static inline void __down_write(struct rw_semaphore *sem)
-{
-	__down_write_nested(sem, 0);
-}
-
 /*
  * trylock for writing -- returns 1 if successful, 0 if contention
  */

arch/sh/include/asm/rwsem.h

@@ -114,11 +114,6 @@ static inline void __downgrade_write(struct rw_semaphore *sem)
 		rwsem_downgrade_wake(sem);
 }
 
-static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
-{
-	__down_write(sem);
-}
-
 /*
  * implement exchange and add functionality
  */

arch/sparc/include/asm/rwsem.h

@@ -45,7 +45,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
 /*
  * lock for writing
  */
-static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
+static inline void __down_write(struct rw_semaphore *sem)
 {
 	long tmp;
 
@@ -55,11 +55,6 @@ static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
 		rwsem_down_write_failed(sem);
 }
 
-static inline void __down_write(struct rw_semaphore *sem)
-{
-	__down_write_nested(sem, 0);
-}
-
 static inline int __down_write_trylock(struct rw_semaphore *sem)
 {
 	long tmp;

arch/x86/include/asm/rwsem.h

@@ -99,7 +99,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
 /*
  * lock for writing
  */
-static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
+static inline void __down_write(struct rw_semaphore *sem)
 {
 	long tmp;
 	asm volatile("# beginning down_write\n\t"
@@ -116,11 +116,6 @@ static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
 		     : "memory", "cc");
 }
 
-static inline void __down_write(struct rw_semaphore *sem)
-{
-	__down_write_nested(sem, 0);
-}
-
 /*
  * trylock for writing -- returns 1 if successful, 0 if contention
  */

include/asm-generic/rwsem.h

@@ -53,7 +53,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
 /*
  * lock for writing
  */
-static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
+static inline void __down_write(struct rw_semaphore *sem)
 {
 	long tmp;
 
@@ -63,11 +63,6 @@ static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
 		rwsem_down_write_failed(sem);
 }
 
-static inline void __down_write(struct rw_semaphore *sem)
-{
-	__down_write_nested(sem, 0);
-}
-
 static inline int __down_write_trylock(struct rw_semaphore *sem)
 {
 	long tmp;

include/linux/rwsem-spinlock.h

@@ -34,7 +34,6 @@ struct rw_semaphore {
 extern void __down_read(struct rw_semaphore *sem);
 extern int __down_read_trylock(struct rw_semaphore *sem);
 extern void __down_write(struct rw_semaphore *sem);
-extern void __down_write_nested(struct rw_semaphore *sem, int subclass);
 extern int __down_write_trylock(struct rw_semaphore *sem);
 extern void __up_read(struct rw_semaphore *sem);
 extern void __up_write(struct rw_semaphore *sem);

kernel/locking/rwsem-spinlock.c

@@ -191,7 +191,7 @@ int __down_read_trylock(struct rw_semaphore *sem)
 /*
  * get a write lock on the semaphore
  */
-void __sched __down_write_nested(struct rw_semaphore *sem, int subclass)
+void __sched __down_write(struct rw_semaphore *sem)
 {
 	struct rwsem_waiter waiter;
 	struct task_struct *tsk;
@@ -227,11 +227,6 @@ void __sched __down_write_nested(struct rw_semaphore *sem, int subclass)
 	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
 }
 
-void __sched __down_write(struct rw_semaphore *sem)
-{
-	__down_write_nested(sem, 0);
-}
-
 /*
  * trylock for writing -- returns 1 if successful, 0 if contention
  */