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-rw-r--r--fs/eventpoll.c18
-rw-r--r--fs/select.c40
-rw-r--r--include/linux/poll.h37
-rw-r--r--include/net/sock.h2
-rw-r--r--net/unix/af_unix.c2
5 files changed, 66 insertions, 33 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 4d9d3a45e356..ca300071e79c 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -699,9 +699,12 @@ static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head,
void *priv)
{
struct epitem *epi, *tmp;
+ poll_table pt;
+ init_poll_funcptr(&pt, NULL);
list_for_each_entry_safe(epi, tmp, head, rdllink) {
- if (epi->ffd.file->f_op->poll(epi->ffd.file, NULL) &
+ pt._key = epi->event.events;
+ if (epi->ffd.file->f_op->poll(epi->ffd.file, &pt) &
epi->event.events)
return POLLIN | POLLRDNORM;
else {
@@ -1097,6 +1100,7 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
/* Initialize the poll table using the queue callback */
epq.epi = epi;
init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);
+ epq.pt._key = event->events;
/*
* Attach the item to the poll hooks and get current event bits.
@@ -1191,6 +1195,9 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_even
{
int pwake = 0;
unsigned int revents;
+ poll_table pt;
+
+ init_poll_funcptr(&pt, NULL);
/*
* Set the new event interest mask before calling f_op->poll();
@@ -1198,13 +1205,14 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_even
* f_op->poll() call and the new event set registering.
*/
epi->event.events = event->events;
+ pt._key = event->events;
epi->event.data = event->data; /* protected by mtx */
/*
* Get current event bits. We can safely use the file* here because
* its usage count has been increased by the caller of this function.
*/
- revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL);
+ revents = epi->ffd.file->f_op->poll(epi->ffd.file, &pt);
/*
* If the item is "hot" and it is not registered inside the ready
@@ -1239,6 +1247,9 @@ static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head,
unsigned int revents;
struct epitem *epi;
struct epoll_event __user *uevent;
+ poll_table pt;
+
+ init_poll_funcptr(&pt, NULL);
/*
* We can loop without lock because we are passed a task private list.
@@ -1251,7 +1262,8 @@ static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head,
list_del_init(&epi->rdllink);
- revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL) &
+ pt._key = epi->event.events;
+ revents = epi->ffd.file->f_op->poll(epi->ffd.file, &pt) &
epi->event.events;
/*
diff --git a/fs/select.c b/fs/select.c
index e782258d0de3..ecfd0b125ba2 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -223,7 +223,7 @@ static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
get_file(filp);
entry->filp = filp;
entry->wait_address = wait_address;
- entry->key = p->key;
+ entry->key = p->_key;
init_waitqueue_func_entry(&entry->wait, pollwake);
entry->wait.private = pwq;
add_wait_queue(wait_address, &entry->wait);
@@ -386,13 +386,11 @@ get_max:
static inline void wait_key_set(poll_table *wait, unsigned long in,
unsigned long out, unsigned long bit)
{
- if (wait) {
- wait->key = POLLEX_SET;
- if (in & bit)
- wait->key |= POLLIN_SET;
- if (out & bit)
- wait->key |= POLLOUT_SET;
- }
+ wait->_key = POLLEX_SET;
+ if (in & bit)
+ wait->_key |= POLLIN_SET;
+ if (out & bit)
+ wait->_key |= POLLOUT_SET;
}
int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
@@ -414,7 +412,7 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
poll_initwait(&table);
wait = &table.pt;
if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
- wait = NULL;
+ wait->_qproc = NULL;
timed_out = 1;
}
@@ -459,17 +457,17 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
if ((mask & POLLIN_SET) && (in & bit)) {
res_in |= bit;
retval++;
- wait = NULL;
+ wait->_qproc = NULL;
}
if ((mask & POLLOUT_SET) && (out & bit)) {
res_out |= bit;
retval++;
- wait = NULL;
+ wait->_qproc = NULL;
}
if ((mask & POLLEX_SET) && (ex & bit)) {
res_ex |= bit;
retval++;
- wait = NULL;
+ wait->_qproc = NULL;
}
}
}
@@ -481,7 +479,7 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
*rexp = res_ex;
cond_resched();
}
- wait = NULL;
+ wait->_qproc = NULL;
if (retval || timed_out || signal_pending(current))
break;
if (table.error) {
@@ -720,7 +718,7 @@ struct poll_list {
* interested in events matching the pollfd->events mask, and the result
* matching that mask is both recorded in pollfd->revents and returned. The
* pwait poll_table will be used by the fd-provided poll handler for waiting,
- * if non-NULL.
+ * if pwait->_qproc is non-NULL.
*/
static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait)
{
@@ -738,9 +736,7 @@ static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait)
if (file != NULL) {
mask = DEFAULT_POLLMASK;
if (file->f_op && file->f_op->poll) {
- if (pwait)
- pwait->key = pollfd->events |
- POLLERR | POLLHUP;
+ pwait->_key = pollfd->events|POLLERR|POLLHUP;
mask = file->f_op->poll(file, pwait);
}
/* Mask out unneeded events. */
@@ -763,7 +759,7 @@ static int do_poll(unsigned int nfds, struct poll_list *list,
/* Optimise the no-wait case */
if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
- pt = NULL;
+ pt->_qproc = NULL;
timed_out = 1;
}
@@ -781,22 +777,22 @@ static int do_poll(unsigned int nfds, struct poll_list *list,
for (; pfd != pfd_end; pfd++) {
/*
* Fish for events. If we found one, record it
- * and kill the poll_table, so we don't
+ * and kill poll_table->_qproc, so we don't
* needlessly register any other waiters after
* this. They'll get immediately deregistered
* when we break out and return.
*/
if (do_pollfd(pfd, pt)) {
count++;
- pt = NULL;
+ pt->_qproc = NULL;
}
}
}
/*
* All waiters have already been registered, so don't provide
- * a poll_table to them on the next loop iteration.
+ * a poll_table->_qproc to them on the next loop iteration.
*/
- pt = NULL;
+ pt->_qproc = NULL;
if (!count) {
count = wait->error;
if (signal_pending(current))
diff --git a/include/linux/poll.h b/include/linux/poll.h
index cf40010ce0cd..48fe8bc398d1 100644
--- a/include/linux/poll.h
+++ b/include/linux/poll.h
@@ -32,21 +32,46 @@ struct poll_table_struct;
*/
typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
+/*
+ * Do not touch the structure directly, use the access functions
+ * poll_does_not_wait() and poll_requested_events() instead.
+ */
typedef struct poll_table_struct {
- poll_queue_proc qproc;
- unsigned long key;
+ poll_queue_proc _qproc;
+ unsigned long _key;
} poll_table;
static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
{
- if (p && wait_address)
- p->qproc(filp, wait_address, p);
+ if (p && p->_qproc && wait_address)
+ p->_qproc(filp, wait_address, p);
+}
+
+/*
+ * Return true if it is guaranteed that poll will not wait. This is the case
+ * if the poll() of another file descriptor in the set got an event, so there
+ * is no need for waiting.
+ */
+static inline bool poll_does_not_wait(const poll_table *p)
+{
+ return p == NULL || p->_qproc == NULL;
+}
+
+/*
+ * Return the set of events that the application wants to poll for.
+ * This is useful for drivers that need to know whether a DMA transfer has
+ * to be started implicitly on poll(). You typically only want to do that
+ * if the application is actually polling for POLLIN and/or POLLOUT.
+ */
+static inline unsigned long poll_requested_events(const poll_table *p)
+{
+ return p ? p->_key : ~0UL;
}
static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
{
- pt->qproc = qproc;
- pt->key = ~0UL; /* all events enabled */
+ pt->_qproc = qproc;
+ pt->_key = ~0UL; /* all events enabled */
}
struct poll_table_entry {
diff --git a/include/net/sock.h b/include/net/sock.h
index 04bc0b30e9e9..a6ba1f8871fd 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1854,7 +1854,7 @@ static inline bool wq_has_sleeper(struct socket_wq *wq)
static inline void sock_poll_wait(struct file *filp,
wait_queue_head_t *wait_address, poll_table *p)
{
- if (p && wait_address) {
+ if (!poll_does_not_wait(p) && wait_address) {
poll_wait(filp, wait_address, p);
/*
* We need to be sure we are in sync with the
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index eb4277c33188..d510353ef431 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2206,7 +2206,7 @@ static unsigned int unix_dgram_poll(struct file *file, struct socket *sock,
}
/* No write status requested, avoid expensive OUT tests. */
- if (wait && !(wait->key & (POLLWRBAND | POLLWRNORM | POLLOUT)))
+ if (!(poll_requested_events(wait) & (POLLWRBAND|POLLWRNORM|POLLOUT)))
return mask;
writable = unix_writable(sk);
generated by cgit v1.2.3 (git 2.0.4) at 2024-05-28 19:11:56 +0000