From: Davide Libenzi Fix epoll to allow pushing of multiple file descriptors sharing the same kernel's file* 25-akpm/fs/eventpoll.c | 41 +++++++++++++++++++++++++---------------- 1 files changed, 25 insertions(+), 16 deletions(-) diff -puN fs/eventpoll.c~epoll-multiple-fds fs/eventpoll.c --- 25/fs/eventpoll.c~epoll-multiple-fds Tue Jul 8 12:04:43 2003 +++ 25-akpm/fs/eventpoll.c Tue Jul 8 12:04:43 2003 @@ -245,6 +245,9 @@ struct epitem { /* The "container" of this item */ struct eventpoll *ep; + /* The file descriptor this item refers to */ + int fd; + /* The file this item refers to */ struct file *file; @@ -285,15 +288,17 @@ static int ep_getfd(int *efd, struct ino static int ep_alloc_pages(char **pages, int numpages); static int ep_free_pages(char **pages, int numpages); static int ep_file_init(struct file *file, unsigned int hashbits); -static unsigned int ep_hash_index(struct eventpoll *ep, struct file *file); +static unsigned int ep_hash_index(struct eventpoll *ep, struct file *file, int fd); static struct list_head *ep_hash_entry(struct eventpoll *ep, unsigned int index); static int ep_init(struct eventpoll *ep, unsigned int hashbits); static void ep_free(struct eventpoll *ep); -static struct epitem *ep_find(struct eventpoll *ep, struct file *file); +static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd); static void ep_use_epitem(struct epitem *epi); static void ep_release_epitem(struct epitem *epi); -static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, poll_table *pt); -static int ep_insert(struct eventpoll *ep, struct epoll_event *event, struct file *tfile); +static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, + poll_table *pt); +static int ep_insert(struct eventpoll *ep, struct epoll_event *event, + struct file *tfile, int fd); static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_event *event); static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi); static int ep_unlink(struct eventpoll *ep, struct epitem *epi); @@ -580,7 +585,7 @@ asmlinkage long sys_epoll_ctl(int epfd, down_write(&ep->sem); /* Try to lookup the file inside our hash table */ - epi = ep_find(ep, tfile); + epi = ep_find(ep, tfile, fd); error = -EINVAL; switch (op) { @@ -588,7 +593,7 @@ asmlinkage long sys_epoll_ctl(int epfd, if (!epi) { epds.events |= POLLERR | POLLHUP; - error = ep_insert(ep, &epds, tfile); + error = ep_insert(ep, &epds, tfile, fd); } else error = -EEXIST; break; @@ -814,10 +819,11 @@ static int ep_file_init(struct file *fil /* * Calculate the index of the hash relative to "file". */ -static unsigned int ep_hash_index(struct eventpoll *ep, struct file *file) +static unsigned int ep_hash_index(struct eventpoll *ep, struct file *file, int fd) { + unsigned long ptr = (unsigned long) file ^ (fd << ep->hashbits); - return (unsigned int) hash_ptr(file, ep->hashbits); + return (unsigned int) hash_ptr((void *) ptr, ep->hashbits); } @@ -920,7 +926,7 @@ static void ep_free(struct eventpoll *ep * the returned item, so the caller must call ep_release_epitem() * after finished using the "struct epitem". */ -static struct epitem *ep_find(struct eventpoll *ep, struct file *file) +static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd) { unsigned long flags; struct list_head *lsthead, *lnk; @@ -928,11 +934,11 @@ static struct epitem *ep_find(struct eve read_lock_irqsave(&ep->lock, flags); - lsthead = ep_hash_entry(ep, ep_hash_index(ep, file)); + lsthead = ep_hash_entry(ep, ep_hash_index(ep, file, fd)); list_for_each(lnk, lsthead) { epi = list_entry(lnk, struct epitem, llink); - if (epi->file == file) { + if (epi->file == file && epi->fd == fd) { ep_use_epitem(epi); break; } @@ -976,7 +982,8 @@ static void ep_release_epitem(struct epi * This is the callback that is used to add our wait queue to the * target file wakeup lists. */ -static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, poll_table *pt) +static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, + poll_table *pt) { struct epitem *epi = EP_ITEM_FROM_EPQUEUE(pt); struct eppoll_entry *pwq; @@ -995,7 +1002,8 @@ static void ep_ptable_queue_proc(struct } -static int ep_insert(struct eventpoll *ep, struct epoll_event *event, struct file *tfile) +static int ep_insert(struct eventpoll *ep, struct epoll_event *event, + struct file *tfile, int fd) { int error, revents, pwake = 0; unsigned long flags; @@ -1014,6 +1022,7 @@ static int ep_insert(struct eventpoll *e INIT_LIST_HEAD(&epi->pwqlist); epi->ep = ep; epi->file = tfile; + epi->fd = fd; epi->event = *event; atomic_set(&epi->usecnt, 1); epi->nwait = 0; @@ -1046,7 +1055,7 @@ static int ep_insert(struct eventpoll *e write_lock_irqsave(&ep->lock, flags); /* Add the current item to the hash table */ - list_add(&epi->llink, ep_hash_entry(ep, ep_hash_index(ep, tfile))); + list_add(&epi->llink, ep_hash_entry(ep, ep_hash_index(ep, tfile, fd))); /* If the file is already "ready" we drop it inside the ready list */ if ((revents & event->events) && !EP_IS_LINKED(&epi->rdllink)) { @@ -1065,8 +1074,8 @@ static int ep_insert(struct eventpoll *e if (pwake) ep_poll_safewake(&psw, &ep->poll_wait); - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_insert(%p, %p)\n", - current, ep, tfile)); + DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_insert(%p, %p, %d)\n", + current, ep, tfile, fd)); return 0; _