locking/arch, alpha: Add __down_read_killable()

Similar to __down_write_killable(), and read killable primitive.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arnd@arndb.de
Cc: avagin@virtuozzo.com
Cc: davem@davemloft.net
Cc: fenghua.yu@intel.com
Cc: gorcunov@virtuozzo.com
Cc: heiko.carstens@de.ibm.com
Cc: hpa@zytor.com
Cc: ink@jurassic.park.msu.ru
Cc: mattst88@gmail.com
Cc: rientjes@google.com
Cc: rth@twiddle.net
Cc: schwidefsky@de.ibm.com
Cc: tony.luck@intel.com
Cc: viro@zeniv.linux.org.uk
Link: http://lkml.kernel.org/r/150670115677.23930.5711263025537758463.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/alpha/include/asm/rwsem.h b/arch/alpha/include/asm/rwsem.h
index 77873d0ad2937b130ab0a8fa737b5a61b821d087..9624cb4cbf2fa388cf09ca2f76ba9e087560da67 100644 (file)
--- a/arch/alpha/include/asm/rwsem.h
+++ b/arch/alpha/include/asm/rwsem.h
@@ -21,7 +21,7 @@
 #define RWSEM_ACTIVE_READ_BIAS         RWSEM_ACTIVE_BIAS
 #define RWSEM_ACTIVE_WRITE_BIAS                (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
 
-static inline void __down_read(struct rw_semaphore *sem)
+static inline int ___down_read(struct rw_semaphore *sem)
 {
        long oldcount;
 #ifndef        CONFIG_SMP
@@ -41,10 +41,24 @@ static inline void __down_read(struct rw_semaphore *sem)
        :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
        :"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory");
 #endif
-       if (unlikely(oldcount < 0))
+       return (oldcount < 0);
+}
+
+static inline void __down_read(struct rw_semaphore *sem)
+{
+       if (unlikely(___down_read(sem)))
                rwsem_down_read_failed(sem);
 }
 
+static inline int __down_read_killable(struct rw_semaphore *sem)
+{
+       if (unlikely(___down_read(sem)))
+               if (IS_ERR(rwsem_down_read_failed_killable(sem)))
+                       return -EINTR;
+
+       return 0;
+}
+
 /*
  * trylock for reading -- returns 1 if successful, 0 if contention
  */
@@ -94,9 +108,10 @@ static inline void __down_write(struct rw_semaphore *sem)
 
 static inline int __down_write_killable(struct rw_semaphore *sem)
 {
-       if (unlikely(___down_write(sem)))
+       if (unlikely(___down_write(sem))) {
                if (IS_ERR(rwsem_down_write_failed_killable(sem)))
                        return -EINTR;
+       }
 
        return 0;
 }