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authorLinus Torvalds <torvalds@linux-foundation.org>2016-08-12 12:46:37 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-08-12 12:46:37 -0700
commit1f8083c640bf08aab8762a9e10326ce767c66492 (patch)
treeccac514a6fd67bca75767af3a9670a2cab7837bd /include
parent25db69188e0369a8c4ac53f71e935a8b6e22e117 (diff)
parentc2ace36b884de9330c4149064ae8d212d2e0d9ee (diff)
downloadlinux-1f8083c640bf08aab8762a9e10326ce767c66492.tar.bz2
Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Ingo Molnar: "Misc fixes: lockstat fix, futex fix on !MMU systems, big endian fix for qrwlocks and a race fix for pvqspinlocks" * 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/pvqspinlock: Fix a bug in qstat_read() locking/pvqspinlock: Fix double hash race locking/qrwlock: Fix write unlock bug on big endian systems futex: Assume all mappings are private on !MMU systems
Diffstat (limited to 'include')
-rw-r--r--include/asm-generic/qrwlock.h27
1 files changed, 25 insertions, 2 deletions
diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h
index 54a8e65e18b6..7d026bf27713 100644
--- a/include/asm-generic/qrwlock.h
+++ b/include/asm-generic/qrwlock.h
@@ -25,7 +25,20 @@
#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_LOCKED 0xff /* A writer holds the lock */
@@ -134,12 +147,22 @@ static inline void queued_read_unlock(struct qrwlock *lock)
}
/**
+ * __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
* @lock : Pointer to queue rwlock structure
*/
static inline void queued_write_unlock(struct qrwlock *lock)
{
- smp_store_release((u8 *)&lock->cnts, 0);
+ smp_store_release(__qrwlock_write_byte(lock), 0);
}
/*