*) Some constant adjusted
*) Comments plus
*) Better hash initialization
*) Correct timeout setup
*) Added __KERNEL__ bypass to avoid userspace inclusion problems
*) Cleaned up locking
*) poll_init_wait() now calls poll_init_wait_ex()
*) event return fix ( Jay Vosburgh )
- Davide
fs/eventpoll.c | 111 ++++++++++++++++++++++++++++------------------
include/linux/eventpoll.h | 14 +++--
include/linux/poll.h | 15 ++----
3 files changed, 83 insertions, 57 deletions
diff -Nru linux-2.5.46.vanilla/fs/eventpoll.c linux-2.5.46.epoll/fs/eventpoll.c
--- linux-2.5.46.vanilla/fs/eventpoll.c Mon Nov 4 15:45:35 2002
+++ linux-2.5.46.epoll/fs/eventpoll.c Wed Nov 6 14:44:44 2002
@@ -61,8 +61,12 @@
/* Maximum storage for the eventpoll interest set */
#define EP_MAX_FDS_SIZE (1024 * 128)
-/* We don't want the hash to be smaller than this */
-#define EP_MIN_HASH_SIZE 101
+/*
+ * We don't want the hash to be smaller than this. This is basically
+ * the highest prime lower than (PAGE_SIZE / sizeof(struct list_head)).
+ */
+#define EP_MIN_HASH_SIZE 509
+
/*
* Event buffer dimension used to cache events before sending them in
* userspace with a __copy_to_user(). The event buffer is in stack,
@@ -188,6 +192,7 @@
static int ep_is_prime(int n);
+static int ep_size_hash(int hintsize);
static int ep_getfd(int *efd, struct inode **einode, struct file **efile);
static int ep_alloc_pages(char **pages, int numpages);
static int ep_free_pages(char **pages, int numpages);
@@ -201,7 +206,6 @@
static void ep_release_epitem(struct epitem *dpi);
static void ep_ptable_queue_proc(void *priv, wait_queue_head_t *whead);
static int ep_insert(struct eventpoll *ep, struct pollfd *pfd, struct file *tfile);
-static unsigned int ep_get_file_events(struct file *file);
static int ep_modify(struct eventpoll *ep, struct epitem *dpi, unsigned int events);
static int ep_unlink(struct eventpoll *ep, struct epitem *dpi);
static int ep_remove(struct eventpoll *ep, struct epitem *dpi);
@@ -252,14 +256,14 @@
-/* Report if the number is prime. Needed to correctly size the hash */
+/* Report if the number is prime. Needed to correctly size the hash */
static int ep_is_prime(int n)
{
if (n > 3) {
if (n & 1) {
int i, hn = n / 2;
-
+
for (i = 3; i < hn; i += 2)
if (!(n % i))
return 0;
@@ -296,9 +300,30 @@
}
+static int ep_size_hash(int hintsize)
+{
+ int maxsize = (EP_MAX_HPAGES - 1) * EP_HENTRY_X_PAGE;
+
+ /*
+ * Search the nearest prime number higher than "hintsize" and
+ * smaller than "maxsize".
+ */
+ for (; !ep_is_prime(hintsize); hintsize++);
+ if (hintsize < EP_MIN_HASH_SIZE)
+ hintsize = EP_MIN_HASH_SIZE;
+ else if (hintsize >= maxsize)
+ for (hintsize = maxsize - 1; !ep_is_prime(hintsize); hintsize--);
+
+ return hintsize;
+}
+
+
/*
* It opens an eventpoll file descriptor by suggesting a storage of "size"
- * file descriptors. It is the kernel part of the userspace epoll_create(2).
+ * file descriptors. The size parameter is just an hint about how to size
+ * data structures. It won't prevent the user to store more than "size"
+ * file descriptors inside the epoll interface. It is the kernel part of
+ * the userspace epoll_create(2).
*/
asmlinkage int sys_epoll_create(int size)
{
@@ -309,10 +334,8 @@
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d)\n",
current, size));
- /* Search the nearest prime number higher than "size" */
- for (; !ep_is_prime(size); size++);
- if (size < EP_MIN_HASH_SIZE)
- size = EP_MIN_HASH_SIZE;
+ /* Correctly size the hash */
+ size = ep_size_hash(size);
/*
* Creates all the items needed to setup an eventpoll file. That is,
@@ -457,6 +480,10 @@
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_wait(%d, %p, %d, %d)\n",
current, epfd, events, maxevents, timeout));
+ /* The maximum number of event must be greater than zero */
+ if (maxevents <= 0)
+ return -EINVAL;
+
/* Verify that the area passed by the user is writeable */
if ((error = verify_area(VERIFY_WRITE, events, maxevents * sizeof(struct pollfd))))
goto eexit_1;
@@ -567,7 +594,7 @@
eexit_2:
put_filp(file);
eexit_1:
- return error;
+ return error;
}
@@ -723,8 +750,7 @@
write_unlock_irqrestore(&eplock, flags);
/* Free hash pages */
- if (ep->nhpages > 0)
- ep_free_pages(ep->hpages, ep->nhpages);
+ ep_free_pages(ep->hpages, ep->nhpages);
}
@@ -827,22 +853,26 @@
dpi->wait[i].base = dpi;
}
- /* Attach the item to the poll hooks */
+ /* Initialize the poll table using the queue callback */
poll_initwait_ex(&pt, 1, ep_ptable_queue_proc, dpi);
- revents = tfile->f_op->poll(tfile, &pt);
- poll_freewait(&pt);
/* We have to drop the new item inside our item list to keep track of it */
write_lock_irqsave(&ep->lock, flags);
+ /* Add the current item to the hash table */
list_add(&dpi->llink, ep_hash_entry(ep, ep_hash_index(ep, tfile)));
+ /* Attach the item to the poll hooks and get current event bits */
+ revents = tfile->f_op->poll(tfile, &pt);
+
/* If the file is already "ready" we drop it inside the ready list */
if ((revents & pfd->events) && !EP_IS_LINKED(&dpi->rdllink))
list_add(&dpi->rdllink, &ep->rdllist);
write_unlock_irqrestore(&ep->lock, flags);
+ poll_freewait(&pt);
+
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_insert(%p, %d)\n",
current, ep, pfd->fd));
@@ -854,12 +884,13 @@
/*
- * Returns the current events of the given file. It uses the special
- * poll table initialization to avoid any poll queue insertion.
+ * Modify the interest event mask by dropping an event if the new mask
+ * has a match in the current file status.
*/
-static unsigned int ep_get_file_events(struct file *file)
+static int ep_modify(struct eventpoll *ep, struct epitem *dpi, unsigned int events)
{
unsigned int revents;
+ unsigned long flags;
poll_table pt;
/*
@@ -870,26 +901,12 @@
*/
poll_initwait_ex(&pt, 0, NULL, NULL);
- revents = file->f_op->poll(file, &pt);
-
- poll_freewait(&pt);
- return revents;
-}
-
-
-/*
- * Modify the interest event mask by dropping an event if the new mask
- * has a match in the current file status.
- */
-static int ep_modify(struct eventpoll *ep, struct epitem *dpi, unsigned int events)
-{
- unsigned int revents;
- unsigned long flags;
-
- revents = ep_get_file_events(dpi->file);
-
write_lock_irqsave(&ep->lock, flags);
+ /* Get current event bits */
+ revents = dpi->file->f_op->poll(dpi->file, &pt);
+
+ /* Set the new event interest mask */
dpi->pfd.events = events;
/* If the file is already "ready" we drop it inside the ready list */
@@ -898,6 +915,8 @@
write_unlock_irqrestore(&ep->lock, flags);
+ poll_freewait(&pt);
+
return 0;
}
@@ -1068,12 +1087,20 @@
write_lock_irqsave(&ep->lock, flags);
- for (eventcnt = 0, ebufcnt = 0; eventcnt < maxevents && !list_empty(lsthead);) {
+ for (eventcnt = 0, ebufcnt = 0; (eventcnt + ebufcnt) < maxevents && !list_empty(lsthead);) {
struct epitem *dpi = list_entry(lsthead->next, struct epitem, rdllink);
/* Remove the item from the ready list */
EP_LIST_DEL(&dpi->rdllink);
+ /*
+ * If the item is not linked to the main has table this means that
+ * it's on the way to be removed and we don't want to send events
+ * to such file descriptor.
+ */
+ if (!EP_IS_LINKED(&dpi->llink))
+ continue;
+
/* Fetch event bits from the signaled file */
revents = dpi->file->f_op->poll(dpi->file, &pt);
@@ -1126,12 +1153,10 @@
wait_queue_t wait;
/*
- * Calculate the timeout by checking for the "infinite" value ( -1 )
- * and the overflow condition ( > MAX_SCHEDULE_TIMEOUT / HZ ). The
- * passed timeout is in milliseconds, that why (t * HZ) / 1000.
+ * Calculate the timeout by checking for the "infinite" value ( -1 ).
+ * The passed timeout is in milliseconds, that why (t * HZ) / 1000.
*/
- jtimeout = timeout == -1 || timeout > MAX_SCHEDULE_TIMEOUT / HZ ?
- MAX_SCHEDULE_TIMEOUT: (timeout * HZ) / 1000;
+ jtimeout = timeout == -1 ? MAX_SCHEDULE_TIMEOUT: (timeout * HZ) / 1000;
retry:
write_lock_irqsave(&ep->lock, flags);
diff -Nru linux-2.5.46.vanilla/include/linux/eventpoll.h linux-2.5.46.epoll/include/linux/eventpoll.h
--- linux-2.5.46.vanilla/include/linux/eventpoll.h Mon Nov 4 15:45:36 2002
+++ linux-2.5.46.epoll/include/linux/eventpoll.h Tue Nov 5 11:13:26 2002
@@ -14,10 +14,6 @@
#ifndef _LINUX_EVENTPOLL_H
#define _LINUX_EVENTPOLL_H
-/* Forward declarations to avoid compiler errors */
-struct file;
-struct pollfd;
-
/* Valid opcodes to issue to sys_epoll_ctl() */
#define EP_CTL_ADD 1
@@ -25,6 +21,13 @@
#define EP_CTL_MOD 3
+#ifdef __KERNEL__
+
+/* Forward declarations to avoid compiler errors */
+struct file;
+struct pollfd;
+
+
/* Kernel space functions implementing the user space "epoll" API */
asmlinkage int sys_epoll_create(int size);
asmlinkage int sys_epoll_ctl(int epfd, int op, int fd, unsigned int events);
@@ -34,6 +37,7 @@
/* Used in fs/file_table.c:__fput() to unlink files from the eventpoll interface */
void ep_notify_file_close(struct file *file);
+#endif /* #ifdef __KERNEL__ */
-#endif
+#endif /* #ifndef _LINUX_EVENTPOLL_H */
diff -Nru linux-2.5.46.vanilla/include/linux/poll.h linux-2.5.46.epoll/include/linux/poll.h
--- linux-2.5.46.vanilla/include/linux/poll.h Mon Nov 4 15:45:37 2002
+++ linux-2.5.46.epoll/include/linux/poll.h Wed Nov 6 10:44:10 2002
@@ -28,15 +28,6 @@
__pollwait(filp, wait_address, p);
}
-static inline void poll_initwait(poll_table* pt)
-{
- pt->queue = 1;
- pt->qproc = NULL;
- pt->priv = NULL;
- pt->error = 0;
- pt->table = NULL;
-}
-
static inline void poll_initwait_ex(poll_table* pt, int queue,
void (*qproc)(void *, wait_queue_head_t *),
void *priv)
@@ -46,6 +37,12 @@
pt->priv = priv;
pt->error = 0;
pt->table = NULL;
+}
+
+static inline void poll_initwait(poll_table* pt)
+{
+
+ poll_initwait_ex(pt, 1, NULL, NULL);
}
extern void poll_freewait(poll_table* pt);
-
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