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epoll: fix epoll's own poll (update)

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Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Davide Libenzi 2009-03-31 15:24:11 -07:00 committed by Linus Torvalds
parent 5071f97ec6
commit 296e236e96
1 changed files with 57 additions and 53 deletions
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110
fs/eventpoll.c
View file

@ -454,9 +454,7 @@ static int ep_scan_ready_list(struct eventpoll *ep,
int error, pwake = 0;
unsigned long flags;
struct epitem *epi, *nepi;
struct list_head txlist;
INIT_LIST_HEAD(&txlist);
LIST_HEAD(txlist);
/*
* We need to lock this because we could be hit by
@ -473,8 +471,7 @@ static int ep_scan_ready_list(struct eventpoll *ep,
* in a lockless way.
*/
spin_lock_irqsave(&ep->lock, flags);
list_splice(&ep->rdllist, &txlist);
INIT_LIST_HEAD(&ep->rdllist);
list_splice_init(&ep->rdllist, &txlist);
ep->ovflist = NULL;
spin_unlock_irqrestore(&ep->lock, flags);
@ -514,8 +511,8 @@ static int ep_scan_ready_list(struct eventpoll *ep,
if (!list_empty(&ep->rdllist)) {
/*
* Wake up (if active) both the eventpoll wait list and the ->poll()
* wait list (delayed after we release the lock).
* Wake up (if active) both the eventpoll wait list and
* the ->poll() wait list (delayed after we release the lock).
*/
if (waitqueue_active(&ep->wq))
wake_up_locked(&ep->wq);
@ -632,7 +629,8 @@ static int ep_eventpoll_release(struct inode *inode, struct file *file)
return 0;
}
static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head, void *priv)
static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head,
void *priv)
{
struct epitem *epi, *tmp;
@ -640,13 +638,14 @@ static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head, voi
if (epi->ffd.file->f_op->poll(epi->ffd.file, NULL) &
epi->event.events)
return POLLIN | POLLRDNORM;
else
else {
/*
* Item has been dropped into the ready list by the poll
* callback, but it's not actually ready, as far as
* caller requested events goes. We can remove it here.
*/
list_del_init(&epi->rdllink);
}
}
return 0;
@ -674,7 +673,7 @@ static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait)
pollflags = ep_call_nested(&poll_readywalk_ncalls, EP_MAX_NESTS,
ep_poll_readyevents_proc, ep, ep);
return pollflags != -1 ? pollflags: 0;
return pollflags != -1 ? pollflags : 0;
}
/* File callbacks that implement the eventpoll file behaviour */
@ -872,9 +871,10 @@ static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
add_wait_queue(whead, &pwq->wait);
list_add_tail(&pwq->llink, &epi->pwqlist);
epi->nwait++;
} else
} else {
/* We have to signal that an error occurred */
epi->nwait = -1;
}
}
static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
@ -1055,62 +1055,65 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_even
return 0;
}
static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head, void *priv)
static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head,
void *priv)
{
struct ep_send_events_data *esed = priv;
int eventcnt;
unsigned int revents;
unsigned int revents;
struct epitem *epi;
struct epoll_event __user *uevent;
/*
/*
* We can loop without lock because we are passed a task private list.
* Items cannot vanish during the loop because ep_scan_ready_list() is
* holding "mtx" during this call.
*/
*/
for (eventcnt = 0, uevent = esed->events;
!list_empty(head) && eventcnt < esed->maxevents;) {
epi = list_first_entry(head, struct epitem, rdllink);
list_del_init(&epi->rdllink);
revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL) &
epi->event.events;
revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL) &
epi->event.events;
/*
/*
* If the event mask intersect the caller-requested one,
* deliver the event to userspace. Again, ep_scan_ready_list()
* is holding "mtx", so no operations coming from userspace
* can change the item.
*/
if (revents) {
*/
if (revents) {
if (__put_user(revents, &uevent->events) ||
__put_user(epi->event.data, &uevent->data))
return eventcnt ? eventcnt: -EFAULT;
eventcnt++;
return eventcnt ? eventcnt : -EFAULT;
eventcnt++;
uevent++;
if (epi->event.events & EPOLLONESHOT)
epi->event.events &= EP_PRIVATE_BITS;
else if (!(epi->event.events & EPOLLET))
/*
* If this file has been added with Level Trigger
* mode, we need to insert back inside the ready
* list, so that the next call to epoll_wait()
* will check again the events availability.
* At this point, noone can insert into ep->rdllist
* besides us. The epoll_ctl() callers are locked
* out by ep_scan_ready_list() holding "mtx" and
* the poll callback will queue them in ep->ovflist.
*/
list_add_tail(&epi->rdllink, &ep->rdllist);
}
}
if (epi->event.events & EPOLLONESHOT)
epi->event.events &= EP_PRIVATE_BITS;
else if (!(epi->event.events & EPOLLET)) {
/*
* If this file has been added with Level
* Trigger mode, we need to insert back inside
* the ready list, so that the next call to
* epoll_wait() will check again the events
* availability. At this point, noone can insert
* into ep->rdllist besides us. The epoll_ctl()
* callers are locked out by
* ep_scan_ready_list() holding "mtx" and the
* poll callback will queue them in ep->ovflist.
*/
list_add_tail(&epi->rdllink, &ep->rdllist);
}
}
}
return eventcnt;
}
static int ep_send_events(struct eventpoll *ep, struct epoll_event __user *events,
int maxevents)
static int ep_send_events(struct eventpoll *ep,
struct epoll_event __user *events, int maxevents)
{
struct ep_send_events_data esed;
@ -1194,40 +1197,41 @@ retry:
*/
SYSCALL_DEFINE1(epoll_create1, int, flags)
{
int error;
struct eventpoll *ep = NULL;
int error, fd = -1;
struct eventpoll *ep;
/* Check the EPOLL_* constant for consistency. */
BUILD_BUG_ON(EPOLL_CLOEXEC != O_CLOEXEC);
if (flags & ~EPOLL_CLOEXEC)
return -EINVAL;
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d)\n",
current, flags));
error = -EINVAL;
if (flags & ~EPOLL_CLOEXEC)
goto error_return;
/*
* Create the internal data structure ("struct eventpoll").
* Create the internal data structure ( "struct eventpoll" ).
*/
error = ep_alloc(&ep);
if (error < 0)
if (error < 0) {
fd = error;
goto error_return;
}
/*
* Creates all the items needed to setup an eventpoll file. That is,
* a file structure and a free file descriptor.
*/
error = anon_inode_getfd("[eventpoll]", &eventpoll_fops, ep,
flags & O_CLOEXEC);
if (error < 0)
fd = anon_inode_getfd("[eventpoll]", &eventpoll_fops, ep,
flags & O_CLOEXEC);
if (fd < 0)
ep_free(ep);
error_return:
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n",
current, flags, error));
current, flags, fd));
return error;
return fd;
}
SYSCALL_DEFINE1(epoll_create, int, size)