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ep_scan_ready_list(): prepare to splitup 

take the stuff done before and after the callback into separate helpers

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2020-08-31 13:06:51 -04:00
parent bde03c4c1a
commit db502f8a3b
1 changed files with 36 additions and 27 deletions
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63
fs/eventpoll.c
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@ -561,28 +561,10 @@ static inline void ep_pm_stay_awake_rcu(struct epitem *epi)
rcu_read_unlock();
}
/**
* ep_scan_ready_list - Scans the ready list in a way that makes possible for
* the scan code, to call f_op->poll(). Also allows for
* O(NumReady) performance.
*
* @ep: Pointer to the epoll private data structure.
* @sproc: Pointer to the scan callback.
* @priv: Private opaque data passed to the @sproc callback.
* @depth: The current depth of recursive f_op->poll calls.
* @ep_locked: caller already holds ep->mtx
*
* Returns: The same integer error code returned by the @sproc callback.
*/
static __poll_t ep_scan_ready_list(struct eventpoll *ep,
__poll_t (*sproc)(struct eventpoll *,
struct list_head *, void *),
void *priv, int depth, bool ep_locked)
static void ep_start_scan(struct eventpoll *ep,
int depth, bool ep_locked,
struct list_head *txlist)
{
__poll_t res;
struct epitem *epi, *nepi;
LIST_HEAD(txlist);
lockdep_assert_irqs_enabled();
/*
@ -602,14 +584,16 @@ static __poll_t ep_scan_ready_list(struct eventpoll *ep,
* in a lockless way.
*/
write_lock_irq(&ep->lock);
list_splice_init(&ep->rdllist, &txlist);
list_splice_init(&ep->rdllist, txlist);
WRITE_ONCE(ep->ovflist, NULL);
write_unlock_irq(&ep->lock);
}
/*
* Now call the callback function.
*/
res = (*sproc)(ep, &txlist, priv);
static void ep_done_scan(struct eventpoll *ep,
int depth, bool ep_locked,
struct list_head *txlist)
{
struct epitem *epi, *nepi;
write_lock_irq(&ep->lock);
/*
@ -644,13 +628,38 @@ static __poll_t ep_scan_ready_list(struct eventpoll *ep,
/*
* Quickly re-inject items left on "txlist".
*/
list_splice(&txlist, &ep->rdllist);
list_splice(txlist, &ep->rdllist);
__pm_relax(ep->ws);
write_unlock_irq(&ep->lock);
if (!ep_locked)
mutex_unlock(&ep->mtx);
}
/**
* ep_scan_ready_list - Scans the ready list in a way that makes possible for
* the scan code, to call f_op->poll(). Also allows for
* O(NumReady) performance.
*
* @ep: Pointer to the epoll private data structure.
* @sproc: Pointer to the scan callback.
* @priv: Private opaque data passed to the @sproc callback.
* @depth: The current depth of recursive f_op->poll calls.
* @ep_locked: caller already holds ep->mtx
*
* Returns: The same integer error code returned by the @sproc callback.
*/
static __poll_t ep_scan_ready_list(struct eventpoll *ep,
__poll_t (*sproc)(struct eventpoll *,
struct list_head *, void *),
void *priv, int depth, bool ep_locked)
{
__poll_t res;
LIST_HEAD(txlist);
ep_start_scan(ep, depth, ep_locked, &txlist);
res = (*sproc)(ep, &txlist, priv);
ep_done_scan(ep, depth, ep_locked, &txlist);
return res;
}