Re: [PATCH] SCHED: allow wait_on_bit_action functions to support a timeout.

From: NeilBrown
Date: Thu May 01 2014 - 05:35:43 EST


On Thu, 1 May 2014 10:04:30 +0200 Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> On Thu, May 01, 2014 at 12:41:43PM +1000, NeilBrown wrote:
> > diff --git a/include/linux/wait.h b/include/linux/wait.h
> > index 438dc6044587..162cbcde9dae 100644
> > --- a/include/linux/wait.h
> > +++ b/include/linux/wait.h
> > @@ -25,6 +25,7 @@ struct wait_bit_key {
> > void *flags;
> > int bit_nr;
> > #define WAIT_ATOMIC_T_BIT_NR -1
> > + unsigned long private;
> > };
> >
> > struct wait_bit_queue {
> > @@ -147,12 +148,12 @@ void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, void *k
> > void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
> > void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
> > void __wake_up_bit(wait_queue_head_t *, void *, int);
> > -int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
> > -int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
> > +int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(struct wait_bit_key *), unsigned);
> > +int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(struct wait_bit_key *), unsigned);
>
>
> Would something like:
>
> typedef int (*wait_bit_action_f)(struct wait_bit_key *);
>
> make sense?

Maybe ... it would be used 12 times.
I usually steer clear of typedefs, but this looks like a reasonably use-case.

This is what the incremental diff would look like. I change the typedef a
little because I like pointers to look like they are pointers.

NeilBrown

diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h
index 592be588ce62..b8703ac18956 100644
--- a/include/linux/sunrpc/sched.h
+++ b/include/linux/sunrpc/sched.h
@@ -236,7 +236,7 @@ void * rpc_malloc(struct rpc_task *, size_t);
void rpc_free(void *);
int rpciod_up(void);
void rpciod_down(void);
-int __rpc_wait_for_completion_task(struct rpc_task *task, int (*)(struct wait_bit_key *));
+int __rpc_wait_for_completion_task(struct rpc_task *task, wait_bit_action_f *);
#ifdef RPC_DEBUG
struct net;
void rpc_show_tasks(struct net *);
diff --git a/include/linux/wait.h b/include/linux/wait.h
index 4cee2b2dc26c..39b6aa4cd636 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -142,18 +142,19 @@ __remove_wait_queue(wait_queue_head_t *head, wait_queue_t *old)
list_del(&old->task_list);
}

+typedef int wait_bit_action_f(struct wait_bit_key *);
void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
void __wake_up_bit(wait_queue_head_t *, void *, int);
-int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(struct wait_bit_key *), unsigned);
-int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(struct wait_bit_key *), unsigned);
+int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
+int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
void wake_up_bit(void *, int);
void wake_up_atomic_t(atomic_t *);
-int out_of_line_wait_on_bit(void *, int, int (*)(struct wait_bit_key *), unsigned);
-int out_of_line_wait_on_bit_lock(void *, int, int (*)(struct wait_bit_key *), unsigned);
+int out_of_line_wait_on_bit(void *, int, wait_bit_action_f *, unsigned);
+int out_of_line_wait_on_bit_lock(void *, int, wait_bit_action_f *, unsigned);
int out_of_line_wait_on_atomic_t(atomic_t *, int (*)(atomic_t *), unsigned);
wait_queue_head_t *bit_waitqueue(void *, int);

@@ -926,7 +927,7 @@ wait_on_bit_io(void *word, int bit, unsigned mode)
* on that signal.
*/
static inline int
-wait_on_bit_action(void *word, int bit, int (*action)(struct wait_bit_key *), unsigned mode)
+wait_on_bit_action(void *word, int bit, wait_bit_action_f *action, unsigned mode)
{
if (!test_bit(bit, word))
return 0;
@@ -1001,7 +1002,7 @@ wait_on_bit_lock_io(void *word, int bit, unsigned mode)
* the @mode allows that signal to wake the process.
*/
static inline int
-wait_on_bit_lock_action(void *word, int bit, int (*action)(struct wait_bit_key *), unsigned mode)
+wait_on_bit_lock_action(void *word, int bit, wait_bit_action_f *action, unsigned mode)
{
if (!test_and_set_bit(bit, word))
return 0;
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 738fa685fd3d..e4f90ba7b4b2 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -319,7 +319,7 @@ EXPORT_SYMBOL(wake_bit_function);
*/
int __sched
__wait_on_bit(wait_queue_head_t *wq, struct wait_bit_queue *q,
- int (*action)(struct wait_bit_key *), unsigned mode)
+ wait_bit_action_f *action, unsigned mode)
{
int ret = 0;

@@ -334,7 +334,7 @@ __wait_on_bit(wait_queue_head_t *wq, struct wait_bit_queue *q,
EXPORT_SYMBOL(__wait_on_bit);

int __sched out_of_line_wait_on_bit(void *word, int bit,
- int (*action)(struct wait_bit_key *), unsigned mode)
+ wait_bit_action_f *action, unsigned mode)
{
wait_queue_head_t *wq = bit_waitqueue(word, bit);
DEFINE_WAIT_BIT(wait, word, bit);
@@ -345,7 +345,7 @@ EXPORT_SYMBOL(out_of_line_wait_on_bit);

int __sched
__wait_on_bit_lock(wait_queue_head_t *wq, struct wait_bit_queue *q,
- int (*action)(struct wait_bit_key *), unsigned mode)
+ wait_bit_action_f *action, unsigned mode)
{
do {
int ret;
@@ -365,7 +365,7 @@ __wait_on_bit_lock(wait_queue_head_t *wq, struct wait_bit_queue *q,
EXPORT_SYMBOL(__wait_on_bit_lock);

int __sched out_of_line_wait_on_bit_lock(void *word, int bit,
- int (*action)(struct wait_bit_key *), unsigned mode)
+ wait_bit_action_f *action, unsigned mode)
{
wait_queue_head_t *wq = bit_waitqueue(word, bit);
DEFINE_WAIT_BIT(wait, word, bit);
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index 7b9a673c6adb..9919b94c525a 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -309,7 +309,7 @@ static int rpc_complete_task(struct rpc_task *task)
* to enforce taking of the wq->lock and hence avoid races with
* rpc_complete_task().
*/
-int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(struct wait_bit_key *))
+int __rpc_wait_for_completion_task(struct rpc_task *task, wait_bit_action_f *action)
{
if (action == NULL)
action = rpc_wait_bit_killable;

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