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authorMichel Lespinasse <walken@google.com>2013-05-07 06:45:49 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-05-07 07:20:15 -0700
commite2d57f782c8a906f80d5b5f54da803c1638929d7 (patch)
tree96a3d2f26b8257d39db40ec4cd3cd52b3ef14588 /lib/rwsem-spinlock.c
parentc1be5a5b1b355d40e6cf79cc979eb66dafa24ad1 (diff)
downloadop-kernel-dev-e2d57f782c8a906f80d5b5f54da803c1638929d7.zip
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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.c19
1 files changed, 11 insertions, 8 deletions
diff --git a/lib/rwsem-spinlock.c b/lib/rwsem-spinlock.c
index 7542afb..5f117f3 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 */
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