diff options
| -rw-r--r-- | fs/select.c | 83 |
1 files changed, 51 insertions, 32 deletions
diff --git a/fs/select.c b/fs/select.c index a8109baa5e46..9c4f0f2604f1 100644 --- a/fs/select.c +++ b/fs/select.c @@ -546,37 +546,38 @@ struct poll_list { #define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd)) -static void do_pollfd(unsigned int num, struct pollfd * fdpage, - poll_table ** pwait, int *count) +/* + * Fish for pollable events on the pollfd->fd file descriptor. We're only + * 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. + */ +static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait) { - int i; - - for (i = 0; i < num; i++) { - int fd; - unsigned int mask; - struct pollfd *fdp; - - mask = 0; - fdp = fdpage+i; - fd = fdp->fd; - if (fd >= 0) { - int fput_needed; - struct file * file = fget_light(fd, &fput_needed); - mask = POLLNVAL; - if (file != NULL) { - mask = DEFAULT_POLLMASK; - if (file->f_op && file->f_op->poll) - mask = file->f_op->poll(file, *pwait); - mask &= fdp->events | POLLERR | POLLHUP; - fput_light(file, fput_needed); - } - if (mask) { - *pwait = NULL; - (*count)++; - } + unsigned int mask; + int fd; + + mask = 0; + fd = pollfd->fd; + if (fd >= 0) { + int fput_needed; + struct file * file; + + file = fget_light(fd, &fput_needed); + mask = POLLNVAL; + if (file != NULL) { + mask = DEFAULT_POLLMASK; + if (file->f_op && file->f_op->poll) + mask = file->f_op->poll(file, pwait); + /* Mask out unneeded events. */ + mask &= pollfd->events | POLLERR | POLLHUP; + fput_light(file, fput_needed); } - fdp->revents = mask; } + pollfd->revents = mask; + + return mask; } static int do_poll(unsigned int nfds, struct poll_list *list, @@ -594,11 +595,29 @@ static int do_poll(unsigned int nfds, struct poll_list *list, long __timeout; set_current_state(TASK_INTERRUPTIBLE); - walk = list; - while(walk != NULL) { - do_pollfd( walk->len, walk->entries, &pt, &count); - walk = walk->next; + for (walk = list; walk != NULL; walk = walk->next) { + struct pollfd * pfd, * pfd_end; + + pfd = walk->entries; + pfd_end = pfd + walk->len; + for (; pfd != pfd_end; pfd++) { + /* + * Fish for events. If we found one, record it + * and kill the poll_table, 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; + } + } } + /* + * All waiters have already been registered, so don't provide + * a poll_table to them on the next loop iteration. + */ pt = NULL; if (count || !*timeout || signal_pending(current)) break; |