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| author | Michel Lespinasse <walken@google.com> | 2013-05-07 06:45:49 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-05-07 07:20:15 -0700 |
| commit | e2d57f782c8a906f80d5b5f54da803c1638929d7 (patch) | |
| tree | 96a3d2f26b8257d39db40ec4cd3cd52b3ef14588 /lib/rwsem-spinlock.c | |
| parent | c1be5a5b1b355d40e6cf79cc979eb66dafa24ad1 (diff) | |
| download | lwn-e2d57f782c8a906f80d5b5f54da803c1638929d7.tar.gz lwn-e2d57f782c8a906f80d5b5f54da803c1638929d7.zip | |
rwsem: make the waiter type an enumeration rather than a bitmask
We are not planning to add some new waiter flags, so we can convert the
waiter type into an enumeration.
Background: David Howells suggested I do this back when I tried adding
a new waiter type for unfair readers. However, I believe the cleanup
applies regardless of that use case.
Signed-off-by: Michel Lespinasse <walken@google.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/rwsem-spinlock.c')
| -rw-r--r-- | lib/rwsem-spinlock.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/lib/rwsem-spinlock.c b/lib/rwsem-spinlock.c index 7542afbb22b3..5f117f37ac0a 100644 --- a/lib/rwsem-spinlock.c +++ b/lib/rwsem-spinlock.c @@ -9,12 +9,15 @@ #include <linux/sched.h> #include <linux/export.h> +enum rwsem_waiter_type { + RWSEM_WAITING_FOR_WRITE, + RWSEM_WAITING_FOR_READ +}; + struct rwsem_waiter { struct list_head list; struct task_struct *task; - unsigned int flags; -#define RWSEM_WAITING_FOR_READ 0x00000001 -#define RWSEM_WAITING_FOR_WRITE 0x00000002 + enum rwsem_waiter_type type; }; int rwsem_is_locked(struct rw_semaphore *sem) @@ -68,7 +71,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wakewrite) waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list); if (!wakewrite) { - if (waiter->flags & RWSEM_WAITING_FOR_WRITE) + if (waiter->type == RWSEM_WAITING_FOR_WRITE) goto out; goto dont_wake_writers; } @@ -78,7 +81,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wakewrite) * to -1 here to indicate we get the lock. Instead, we wake it up * to let it go get it again. */ - if (waiter->flags & RWSEM_WAITING_FOR_WRITE) { + if (waiter->type == RWSEM_WAITING_FOR_WRITE) { wake_up_process(waiter->task); goto out; } @@ -86,7 +89,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wakewrite) /* grant an infinite number of read locks to the front of the queue */ dont_wake_writers: woken = 0; - while (waiter->flags & RWSEM_WAITING_FOR_READ) { + while (waiter->type == RWSEM_WAITING_FOR_READ) { struct list_head *next = waiter->list.next; list_del(&waiter->list); @@ -144,7 +147,7 @@ void __sched __down_read(struct rw_semaphore *sem) /* set up my own style of waitqueue */ waiter.task = tsk; - waiter.flags = RWSEM_WAITING_FOR_READ; + waiter.type = RWSEM_WAITING_FOR_READ; get_task_struct(tsk); list_add_tail(&waiter.list, &sem->wait_list); @@ -201,7 +204,7 @@ void __sched __down_write_nested(struct rw_semaphore *sem, int subclass) /* set up my own style of waitqueue */ tsk = current; waiter.task = tsk; - waiter.flags = RWSEM_WAITING_FOR_WRITE; + waiter.type = RWSEM_WAITING_FOR_WRITE; list_add_tail(&waiter.list, &sem->wait_list); /* wait for someone to release the lock */ |