Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 2db34e8b authored by pan xinhui's avatar pan xinhui Committed by Ingo Molnar
Browse files

locking/qrwlock: Fix write unlock bug on big endian systems 



This patch aims to get rid of endianness in queued_write_unlock(). We
want to set  __qrwlock->wmode to NULL, however the address is not
&lock->cnts in big endian machine. That causes queued_write_unlock()
write NULL to the wrong field of __qrwlock.

So implement __qrwlock_write_byte() which returns the correct
__qrwlock->wmode address.

Suggested-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarPan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman.Long@hpe.com
Cc: arnd@arndb.de
Cc: boqun.feng@gmail.com
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1468835259-4486-1-git-send-email-xinhui.pan@linux.vnet.ibm.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent a2071cd7

include/asm-generic/qrwlock.h

+25 −2
Original line number Original line Diff line number Diff line
@@ -25,7 +25,20 @@ 
#include <asm-generic/qrwlock_types.h>

#include <asm-generic/qrwlock_types.h>





/*

/*

 * Writer states & reader shift and bias

 * Writer states & reader shift and bias.

 *

 *       | +0 | +1 | +2 | +3 |

 *   ----+----+----+----+----+

 *    LE | 78 | 56 | 34 | 12 | 0x12345678

 *   ----+----+----+----+----+

 *       | wr |      rd      |

 *       +----+----+----+----+

 *

 *   ----+----+----+----+----+

 *    BE | 12 | 34 | 56 | 78 | 0x12345678

 *   ----+----+----+----+----+

 *       |      rd      | wr |

 *       +----+----+----+----+

 */

 */

#define	_QW_WAITING	1		/* A writer is waiting	   */

#define	_QW_WAITING	1		/* A writer is waiting	   */

#define	_QW_LOCKED	0xff		/* A writer holds the lock */

#define	_QW_LOCKED	0xff		/* A writer holds the lock */
@@ -133,13 +146,23 @@ static inline void queued_read_unlock(struct qrwlock *lock) 
	(void)atomic_sub_return_release(_QR_BIAS, &lock->cnts);

	(void)atomic_sub_return_release(_QR_BIAS, &lock->cnts);

}

}





/**

 * __qrwlock_write_byte - retrieve the write byte address of a queue rwlock

 * @lock : Pointer to queue rwlock structure

 * Return: the write byte address of a queue rwlock

 */

static inline u8 *__qrwlock_write_byte(struct qrwlock *lock)

{

	return (u8 *)lock + 3 * IS_BUILTIN(CONFIG_CPU_BIG_ENDIAN);

}



/**

/**

 * queued_write_unlock - release write lock of a queue rwlock

 * queued_write_unlock - release write lock of a queue rwlock

 * @lock : Pointer to queue rwlock structure

 * @lock : Pointer to queue rwlock structure

 */

 */

static inline void queued_write_unlock(struct qrwlock *lock)

static inline void queued_write_unlock(struct qrwlock *lock)

{

{

	smp_store_release((u8 *)&lock->cnts, 0);

	smp_store_release(__qrwlock_write_byte(lock), 0);

}

}





/*

/*