From: Davide Libenzi <davidel@xmailserver.org>
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;
_