/*
* fs/eventpoll.c ( Efficent event polling implementation )
- * Copyright (C) 2001,...,2003 Davide Libenzi
+ * Copyright (C) 2001,...,2006 Davide Libenzi
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/poll.h>
-#include <linux/smp_lock.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/hash.h>
#include <linux/eventpoll.h>
#include <linux/mount.h>
#include <linux/bitops.h>
+#include <linux/mutex.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
* LOCKING:
* There are three level of locking required by epoll :
*
- * 1) epsem (semaphore)
+ * 1) epmutex (mutex)
* 2) ep->sem (rw_semaphore)
* 3) ep->lock (rw_lock)
*
* if a file has been pushed inside an epoll set and it is then
* close()d without a previous call toepoll_ctl(EPOLL_CTL_DEL).
* It is possible to drop the "ep->sem" and to use the global
- * semaphore "epsem" (together with "ep->lock") to have it working,
+ * semaphore "epmutex" (together with "ep->lock") to have it working,
* but having "ep->sem" will make the interface more scalable.
- * Events that require holding "epsem" are very rare, while for
+ * Events that require holding "epmutex" are very rare, while for
* normal operations the epoll private "ep->sem" will guarantee
* a greater scalability.
*/
/* Maximum number of poll wake up nests we are allowing */
#define EP_MAX_POLLWAKE_NESTS 4
-/* Macro to allocate a "struct epitem" from the slab cache */
-#define EPI_MEM_ALLOC() (struct epitem *) kmem_cache_alloc(epi_cache, SLAB_KERNEL)
+/* Maximum msec timeout value storeable in a long int */
+#define EP_MAX_MSTIMEO min(1000ULL * MAX_SCHEDULE_TIMEOUT / HZ, (LONG_MAX - 999ULL) / HZ)
-/* Macro to free a "struct epitem" to the slab cache */
-#define EPI_MEM_FREE(p) kmem_cache_free(epi_cache, p)
-
-/* Macro to allocate a "struct eppoll_entry" from the slab cache */
-#define PWQ_MEM_ALLOC() (struct eppoll_entry *) kmem_cache_alloc(pwq_cache, SLAB_KERNEL)
-
-/* Macro to free a "struct eppoll_entry" to the slab cache */
-#define PWQ_MEM_FREE(p) kmem_cache_free(pwq_cache, p)
-
-/* Fast test to see if the file is an evenpoll file */
-#define IS_FILE_EPOLL(f) ((f)->f_op == &eventpoll_fops)
-
-/* Setup the structure that is used as key for the rb-tree */
-#define EP_SET_FFD(p, f, d) do { (p)->file = (f); (p)->fd = (d); } while (0)
-
-/* Compare rb-tree keys */
-#define EP_CMP_FFD(p1, p2) ((p1)->file > (p2)->file ? +1: \
- ((p1)->file < (p2)->file ? -1: (p1)->fd - (p2)->fd))
-
-/* Special initialization for the rb-tree node to detect linkage */
-#define EP_RB_INITNODE(n) (n)->rb_parent = (n)
-
-/* Removes a node from the rb-tree and marks it for a fast is-linked check */
-#define EP_RB_ERASE(n, r) do { rb_erase(n, r); (n)->rb_parent = (n); } while (0)
-
-/* Fast check to verify that the item is linked to the main rb-tree */
-#define EP_RB_LINKED(n) ((n)->rb_parent != (n))
-
-/*
- * Remove the item from the list and perform its initialization.
- * This is useful for us because we can test if the item is linked
- * using "EP_IS_LINKED(p)".
- */
-#define EP_LIST_DEL(p) do { list_del(p); INIT_LIST_HEAD(p); } while (0)
-
-/* Tells us if the item is currently linked */
-#define EP_IS_LINKED(p) (!list_empty(p))
-
-/* Get the "struct epitem" from a wait queue pointer */
-#define EP_ITEM_FROM_WAIT(p) ((struct epitem *) container_of(p, struct eppoll_entry, wait)->base)
-
-/* Get the "struct epitem" from an epoll queue wrapper */
-#define EP_ITEM_FROM_EPQUEUE(p) (container_of(p, struct ep_pqueue, pt)->epi)
-
-/* Tells if the epoll_ctl(2) operation needs an event copy from userspace */
-#define EP_OP_HASH_EVENT(op) ((op) != EPOLL_CTL_DEL)
+#define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event))
struct epoll_filefd {
*/
struct wake_task_node {
struct list_head llink;
- task_t *task;
+ struct task_struct *task;
wait_queue_head_t *wq;
};
/*
* Each file descriptor added to the eventpoll interface will
- * have an entry of this type linked to the hash.
+ * have an entry of this type linked to the "rbr" RB tree.
*/
struct epitem {
/* RB-Tree node used to link this structure to the eventpoll rb-tree */
/* List header used to link this item to the "struct file" items list */
struct list_head fllink;
-
- /* List header used to link the item to the transfer list */
- struct list_head txlink;
-
- /*
- * This is used during the collection/transfer of events to userspace
- * to pin items empty events set.
- */
- unsigned int revents;
};
/* Wrapper struct used by poll queueing */
static void ep_poll_safewake_init(struct poll_safewake *psw);
static void ep_poll_safewake(struct poll_safewake *psw, wait_queue_head_t *wq);
-static int ep_getfd(int *efd, struct inode **einode, struct file **efile);
-static int ep_file_init(struct file *file);
+static int ep_getfd(int *efd, struct inode **einode, struct file **efile,
+ struct eventpoll *ep);
+static int ep_alloc(struct eventpoll **pep);
static void ep_free(struct eventpoll *ep);
static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd);
static void ep_use_epitem(struct epitem *epi);
static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *key);
static int ep_eventpoll_close(struct inode *inode, struct file *file);
static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait);
-static int ep_collect_ready_items(struct eventpoll *ep,
- struct list_head *txlist, int maxevents);
static int ep_send_events(struct eventpoll *ep, struct list_head *txlist,
- struct epoll_event __user *events);
-static void ep_reinject_items(struct eventpoll *ep, struct list_head *txlist);
+ struct epoll_event __user *events, int maxevents);
static int ep_events_transfer(struct eventpoll *ep,
struct epoll_event __user *events,
int maxevents);
int maxevents, long timeout);
static int eventpollfs_delete_dentry(struct dentry *dentry);
static struct inode *ep_eventpoll_inode(void);
-static struct super_block *eventpollfs_get_sb(struct file_system_type *fs_type,
- int flags, const char *dev_name,
- void *data);
+static int eventpollfs_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name,
+ void *data, struct vfsmount *mnt);
/*
* This semaphore is used to serialize ep_free() and eventpoll_release_file().
*/
-static struct semaphore epsem;
+static struct mutex epmutex;
/* Safe wake up implementation */
static struct poll_safewake psw;
/* Slab cache used to allocate "struct epitem" */
-static kmem_cache_t *epi_cache;
+static struct kmem_cache *epi_cache __read_mostly;
/* Slab cache used to allocate "struct eppoll_entry" */
-static kmem_cache_t *pwq_cache;
+static struct kmem_cache *pwq_cache __read_mostly;
/* Virtual fs used to allocate inodes for eventpoll files */
-static struct vfsmount *eventpoll_mnt;
+static struct vfsmount *eventpoll_mnt __read_mostly;
/* File callbacks that implement the eventpoll file behaviour */
-static struct file_operations eventpoll_fops = {
+static const struct file_operations eventpoll_fops = {
.release = ep_eventpoll_close,
.poll = ep_eventpoll_poll
};
+/* Fast test to see if the file is an evenpoll file */
+static inline int is_file_epoll(struct file *f)
+{
+ return f->f_op == &eventpoll_fops;
+}
+
+/* Setup the structure that is used as key for the rb-tree */
+static inline void ep_set_ffd(struct epoll_filefd *ffd,
+ struct file *file, int fd)
+{
+ ffd->file = file;
+ ffd->fd = fd;
+}
+
+/* Compare rb-tree keys */
+static inline int ep_cmp_ffd(struct epoll_filefd *p1,
+ struct epoll_filefd *p2)
+{
+ return (p1->file > p2->file ? +1:
+ (p1->file < p2->file ? -1 : p1->fd - p2->fd));
+}
+
+/* Special initialization for the rb-tree node to detect linkage */
+static inline void ep_rb_initnode(struct rb_node *n)
+{
+ rb_set_parent(n, n);
+}
+
+/* Removes a node from the rb-tree and marks it for a fast is-linked check */
+static inline void ep_rb_erase(struct rb_node *n, struct rb_root *r)
+{
+ rb_erase(n, r);
+ rb_set_parent(n, n);
+}
+
+/* Fast check to verify that the item is linked to the main rb-tree */
+static inline int ep_rb_linked(struct rb_node *n)
+{
+ return rb_parent(n) != n;
+}
+
+/* Tells us if the item is currently linked */
+static inline int ep_is_linked(struct list_head *p)
+{
+ return !list_empty(p);
+}
+
+/* Get the "struct epitem" from a wait queue pointer */
+static inline struct epitem * ep_item_from_wait(wait_queue_t *p)
+{
+ return container_of(p, struct eppoll_entry, wait)->base;
+}
+
+/* Get the "struct epitem" from an epoll queue wrapper */
+static inline struct epitem * ep_item_from_epqueue(poll_table *p)
+{
+ return container_of(p, struct ep_pqueue, pt)->epi;
+}
+
+/* Tells if the epoll_ctl(2) operation needs an event copy from userspace */
+static inline int ep_op_has_event(int op)
+{
+ return op != EPOLL_CTL_DEL;
+}
+
/* Initialize the poll safe wake up structure */
static void ep_poll_safewake_init(struct poll_safewake *psw)
{
{
int wake_nests = 0;
unsigned long flags;
- task_t *this_task = current;
+ struct task_struct *this_task = current;
struct list_head *lsthead = &psw->wake_task_list, *lnk;
struct wake_task_node *tncur;
struct wake_task_node tnode;
}
-/* Used to initialize the epoll bits inside the "struct file" */
-void eventpoll_init_file(struct file *file)
-{
-
- INIT_LIST_HEAD(&file->f_ep_links);
- spin_lock_init(&file->f_ep_lock);
-}
-
-
/*
* This is called from eventpoll_release() to unlink files from the eventpoll
* interface. We need to have this facility to cleanup correctly files that are
* cleanup path, and this means that noone is using this file anymore.
* The only hit might come from ep_free() but by holding the semaphore
* will correctly serialize the operation. We do need to acquire
- * "ep->sem" after "epsem" because ep_remove() requires it when called
+ * "ep->sem" after "epmutex" because ep_remove() requires it when called
* from anywhere but ep_free().
*/
- down(&epsem);
+ mutex_lock(&epmutex);
while (!list_empty(lsthead)) {
- epi = list_entry(lsthead->next, struct epitem, fllink);
+ epi = list_first_entry(lsthead, struct epitem, fllink);
ep = epi->ep;
- EP_LIST_DEL(&epi->fllink);
+ list_del_init(&epi->fllink);
down_write(&ep->sem);
ep_remove(ep, epi);
up_write(&ep->sem);
}
- up(&epsem);
+ mutex_unlock(&epmutex);
}
*/
asmlinkage long sys_epoll_create(int size)
{
- int error, fd;
+ int error, fd = -1;
+ struct eventpoll *ep;
struct inode *inode;
struct file *file;
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d)\n",
current, size));
- /* Sanity check on the size parameter */
+ /*
+ * Sanity check on the size parameter, and create the internal data
+ * structure ( "struct eventpoll" ).
+ */
error = -EINVAL;
- if (size <= 0)
+ if (size <= 0 || (error = ep_alloc(&ep)) != 0)
goto eexit_1;
/*
* Creates all the items needed to setup an eventpoll file. That is,
* a file structure, and inode and a free file descriptor.
*/
- error = ep_getfd(&fd, &inode, &file);
- if (error)
- goto eexit_1;
-
- /* Setup the file internal data structure ( "struct eventpoll" ) */
- error = ep_file_init(file);
+ error = ep_getfd(&fd, &inode, &file, ep);
if (error)
goto eexit_2;
-
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n",
current, size, fd));
return fd;
eexit_2:
- sys_close(fd);
+ ep_free(ep);
+ kfree(ep);
eexit_1:
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n",
current, size, error));
current, epfd, op, fd, event));
error = -EFAULT;
- if (EP_OP_HASH_EVENT(op) &&
+ if (ep_op_has_event(op) &&
copy_from_user(&epds, event, sizeof(struct epoll_event)))
goto eexit_1;
* adding an epoll file descriptor inside itself.
*/
error = -EINVAL;
- if (file == tfile || !IS_FILE_EPOLL(file))
+ if (file == tfile || !is_file_epoll(file))
goto eexit_3;
/*
down_write(&ep->sem);
- /* Try to lookup the file inside our hash table */
+ /* Try to lookup the file inside our RB tree */
epi = ep_find(ep, tfile, fd);
error = -EINVAL;
return error;
}
-#define MAX_EVENTS (INT_MAX / sizeof(struct epoll_event))
/*
* Implement the event wait interface for the eventpoll file. It is the kernel
current, epfd, events, maxevents, timeout));
/* The maximum number of event must be greater than zero */
- if (maxevents <= 0 || maxevents > MAX_EVENTS)
+ if (maxevents <= 0 || maxevents > EP_MAX_EVENTS)
return -EINVAL;
/* Verify that the area passed by the user is writeable */
* the user passed to us _is_ an eventpoll file.
*/
error = -EINVAL;
- if (!IS_FILE_EPOLL(file))
+ if (!is_file_epoll(file))
goto eexit_2;
/*
}
+#ifdef TIF_RESTORE_SIGMASK
+
+/*
+ * Implement the event wait interface for the eventpoll file. It is the kernel
+ * part of the user space epoll_pwait(2).
+ */
+asmlinkage long sys_epoll_pwait(int epfd, struct epoll_event __user *events,
+ int maxevents, int timeout, const sigset_t __user *sigmask,
+ size_t sigsetsize)
+{
+ int error;
+ sigset_t ksigmask, sigsaved;
+
+ /*
+ * If the caller wants a certain signal mask to be set during the wait,
+ * we apply it here.
+ */
+ if (sigmask) {
+ if (sigsetsize != sizeof(sigset_t))
+ return -EINVAL;
+ if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
+ return -EFAULT;
+ sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
+ sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+ }
+
+ error = sys_epoll_wait(epfd, events, maxevents, timeout);
+
+ /*
+ * If we changed the signal mask, we need to restore the original one.
+ * In case we've got a signal while waiting, we do not restore the
+ * signal mask yet, and we allow do_signal() to deliver the signal on
+ * the way back to userspace, before the signal mask is restored.
+ */
+ if (sigmask) {
+ if (error == -EINTR) {
+ memcpy(¤t->saved_sigmask, &sigsaved,
+ sizeof(sigsaved));
+ set_thread_flag(TIF_RESTORE_SIGMASK);
+ } else
+ sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+ }
+
+ return error;
+}
+
+#endif /* #ifdef TIF_RESTORE_SIGMASK */
+
+
/*
* Creates the file descriptor to be used by the epoll interface.
*/
-static int ep_getfd(int *efd, struct inode **einode, struct file **efile)
+static int ep_getfd(int *efd, struct inode **einode, struct file **efile,
+ struct eventpoll *ep)
{
struct qstr this;
char name[32];
/* Allocates an inode from the eventpoll file system */
inode = ep_eventpoll_inode();
- error = PTR_ERR(inode);
- if (IS_ERR(inode))
+ if (IS_ERR(inode)) {
+ error = PTR_ERR(inode);
goto eexit_2;
+ }
/* Allocates a free descriptor to plug the file onto */
error = get_unused_fd();
goto eexit_4;
dentry->d_op = &eventpollfs_dentry_operations;
d_add(dentry, inode);
- file->f_vfsmnt = mntget(eventpoll_mnt);
- file->f_dentry = dentry;
+ file->f_path.mnt = mntget(eventpoll_mnt);
+ file->f_path.dentry = dentry;
file->f_mapping = inode->i_mapping;
file->f_pos = 0;
file->f_op = &eventpoll_fops;
file->f_mode = FMODE_READ;
file->f_version = 0;
- file->private_data = NULL;
+ file->private_data = ep;
/* Install the new setup file into the allocated fd. */
fd_install(fd, file);
}
-static int ep_file_init(struct file *file)
+static int ep_alloc(struct eventpoll **pep)
{
- struct eventpoll *ep;
+ struct eventpoll *ep = kzalloc(sizeof(*ep), GFP_KERNEL);
- if (!(ep = kmalloc(sizeof(struct eventpoll), GFP_KERNEL)))
+ if (!ep)
return -ENOMEM;
- memset(ep, 0, sizeof(*ep));
rwlock_init(&ep->lock);
init_rwsem(&ep->sem);
init_waitqueue_head(&ep->wq);
INIT_LIST_HEAD(&ep->rdllist);
ep->rbr = RB_ROOT;
- file->private_data = ep;
+ *pep = ep;
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_file_init() ep=%p\n",
+ DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_alloc() ep=%p\n",
current, ep));
return 0;
}
* We do not need to hold "ep->sem" here because the epoll file
* is on the way to be removed and no one has references to it
* anymore. The only hit might come from eventpoll_release_file() but
- * holding "epsem" is sufficent here.
+ * holding "epmutex" is sufficent here.
*/
- down(&epsem);
+ mutex_lock(&epmutex);
/*
* Walks through the whole tree by unregistering poll callbacks.
}
/*
- * Walks through the whole hash by freeing each "struct epitem". At this
+ * Walks through the whole tree by freeing each "struct epitem". At this
* point we are sure no poll callbacks will be lingering around, and also by
* write-holding "sem" we can be sure that no file cleanup code will hit
* us during this operation. So we can avoid the lock on "ep->lock".
ep_remove(ep, epi);
}
- up(&epsem);
+ mutex_unlock(&epmutex);
}
/*
- * Search the file inside the eventpoll hash. It add usage count to
+ * Search the file inside the eventpoll tree. It add usage count to
* the returned item, so the caller must call ep_release_epitem()
* after finished using the "struct epitem".
*/
struct epitem *epi, *epir = NULL;
struct epoll_filefd ffd;
- EP_SET_FFD(&ffd, file, fd);
+ ep_set_ffd(&ffd, file, fd);
read_lock_irqsave(&ep->lock, flags);
for (rbp = ep->rbr.rb_node; rbp; ) {
epi = rb_entry(rbp, struct epitem, rbn);
- kcmp = EP_CMP_FFD(&ffd, &epi->ffd);
+ kcmp = ep_cmp_ffd(&ffd, &epi->ffd);
if (kcmp > 0)
rbp = rbp->rb_right;
else if (kcmp < 0)
{
if (atomic_dec_and_test(&epi->usecnt))
- EPI_MEM_FREE(epi);
+ kmem_cache_free(epi_cache, epi);
}
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 epitem *epi = ep_item_from_epqueue(pt);
struct eppoll_entry *pwq;
- if (epi->nwait >= 0 && (pwq = PWQ_MEM_ALLOC())) {
+ if (epi->nwait >= 0 && (pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL))) {
init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
pwq->whead = whead;
pwq->base = epi;
while (*p) {
parent = *p;
epic = rb_entry(parent, struct epitem, rbn);
- kcmp = EP_CMP_FFD(&epi->ffd, &epic->ffd);
+ kcmp = ep_cmp_ffd(&epi->ffd, &epic->ffd);
if (kcmp > 0)
p = &parent->rb_right;
else
struct ep_pqueue epq;
error = -ENOMEM;
- if (!(epi = EPI_MEM_ALLOC()))
+ if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL)))
goto eexit_1;
/* Item initialization follow here ... */
- EP_RB_INITNODE(&epi->rbn);
+ ep_rb_initnode(&epi->rbn);
INIT_LIST_HEAD(&epi->rdllink);
INIT_LIST_HEAD(&epi->fllink);
- INIT_LIST_HEAD(&epi->txlink);
INIT_LIST_HEAD(&epi->pwqlist);
epi->ep = ep;
- EP_SET_FFD(&epi->ffd, tfile, fd);
+ ep_set_ffd(&epi->ffd, tfile, fd);
epi->event = *event;
atomic_set(&epi->usecnt, 1);
epi->nwait = 0;
ep_rbtree_insert(ep, epi);
/* If the file is already "ready" we drop it inside the ready list */
- if ((revents & event->events) && !EP_IS_LINKED(&epi->rdllink)) {
+ if ((revents & event->events) && !ep_is_linked(&epi->rdllink)) {
list_add_tail(&epi->rdllink, &ep->rdllist);
/* Notify waiting tasks that events are available */
if (waitqueue_active(&ep->wq))
- wake_up(&ep->wq);
+ __wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE);
if (waitqueue_active(&ep->poll_wait))
pwake++;
}
* allocated wait queue.
*/
write_lock_irqsave(&ep->lock, flags);
- if (EP_IS_LINKED(&epi->rdllink))
- EP_LIST_DEL(&epi->rdllink);
+ if (ep_is_linked(&epi->rdllink))
+ list_del_init(&epi->rdllink);
write_unlock_irqrestore(&ep->lock, flags);
- EPI_MEM_FREE(epi);
+ kmem_cache_free(epi_cache, epi);
eexit_1:
return error;
}
epi->event.data = event->data;
/*
- * If the item is not linked to the hash it means that it's on its
+ * If the item is not linked to the RB tree it means that it's on its
* way toward the removal. Do nothing in this case.
*/
- if (EP_RB_LINKED(&epi->rbn)) {
+ if (ep_rb_linked(&epi->rbn)) {
/*
* If the item is "hot" and it is not registered inside the ready
* list, push it inside. If the item is not "hot" and it is currently
* registered inside the ready list, unlink it.
*/
if (revents & event->events) {
- if (!EP_IS_LINKED(&epi->rdllink)) {
+ if (!ep_is_linked(&epi->rdllink)) {
list_add_tail(&epi->rdllink, &ep->rdllist);
/* Notify waiting tasks that events are available */
if (waitqueue_active(&ep->wq))
- wake_up(&ep->wq);
+ __wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE |
+ TASK_INTERRUPTIBLE);
if (waitqueue_active(&ep->poll_wait))
pwake++;
}
if (nwait) {
while (!list_empty(lsthead)) {
- pwq = list_entry(lsthead->next, struct eppoll_entry, llink);
+ pwq = list_first_entry(lsthead, struct eppoll_entry, llink);
- EP_LIST_DEL(&pwq->llink);
+ list_del_init(&pwq->llink);
remove_wait_queue(pwq->whead, &pwq->wait);
- PWQ_MEM_FREE(pwq);
+ kmem_cache_free(pwq_cache, pwq);
}
}
}
* The check protect us from doing a double unlink ( crash ).
*/
error = -ENOENT;
- if (!EP_RB_LINKED(&epi->rbn))
+ if (!ep_rb_linked(&epi->rbn))
goto eexit_1;
/*
* This operation togheter with the above check closes the door to
* double unlinks.
*/
- EP_RB_ERASE(&epi->rbn, &ep->rbr);
+ ep_rb_erase(&epi->rbn, &ep->rbr);
/*
* If the item we are going to remove is inside the ready file descriptors
* we want to remove it from this list to avoid stale events.
*/
- if (EP_IS_LINKED(&epi->rdllink))
- EP_LIST_DEL(&epi->rdllink);
+ if (ep_is_linked(&epi->rdllink))
+ list_del_init(&epi->rdllink);
error = 0;
eexit_1:
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_unlink(%p, %p) = %d\n",
- current, ep, epi->file, error));
+ current, ep, epi->ffd.file, error));
return error;
}
/*
- * Removes a "struct epitem" from the eventpoll hash and deallocates
+ * Removes a "struct epitem" from the eventpoll RB tree and deallocates
* all the associated resources.
*/
static int ep_remove(struct eventpoll *ep, struct epitem *epi)
/* Remove the current item from the list of epoll hooks */
spin_lock(&file->f_ep_lock);
- if (EP_IS_LINKED(&epi->fllink))
- EP_LIST_DEL(&epi->fllink);
+ if (ep_is_linked(&epi->fllink))
+ list_del_init(&epi->fllink);
spin_unlock(&file->f_ep_lock);
/* We need to acquire the write IRQ lock before calling ep_unlink() */
write_lock_irqsave(&ep->lock, flags);
- /* Really unlink the item from the hash */
+ /* Really unlink the item from the RB tree */
error = ep_unlink(ep, epi);
write_unlock_irqrestore(&ep->lock, flags);
{
int pwake = 0;
unsigned long flags;
- struct epitem *epi = EP_ITEM_FROM_WAIT(wait);
+ struct epitem *epi = ep_item_from_wait(wait);
struct eventpoll *ep = epi->ep;
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: poll_callback(%p) epi=%p ep=%p\n",
- current, epi->file, epi, ep));
+ current, epi->ffd.file, epi, ep));
write_lock_irqsave(&ep->lock, flags);
goto is_disabled;
/* If this file is already in the ready list we exit soon */
- if (EP_IS_LINKED(&epi->rdllink))
+ if (ep_is_linked(&epi->rdllink))
goto is_linked;
list_add_tail(&epi->rdllink, &ep->rdllist);
* wait list.
*/
if (waitqueue_active(&ep->wq))
- wake_up(&ep->wq);
+ __wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE |
+ TASK_INTERRUPTIBLE);
if (waitqueue_active(&ep->poll_wait))
pwake++;
/*
- * Since we have to release the lock during the __copy_to_user() operation and
- * during the f_op->poll() call, we try to collect the maximum number of items
- * by reducing the irqlock/irqunlock switching rate.
- */
-static int ep_collect_ready_items(struct eventpoll *ep, struct list_head *txlist, int maxevents)
-{
- int nepi;
- unsigned long flags;
- struct list_head *lsthead = &ep->rdllist, *lnk;
- struct epitem *epi;
-
- write_lock_irqsave(&ep->lock, flags);
-
- for (nepi = 0, lnk = lsthead->next; lnk != lsthead && nepi < maxevents;) {
- epi = list_entry(lnk, struct epitem, rdllink);
-
- lnk = lnk->next;
-
- /* If this file is already in the ready list we exit soon */
- if (!EP_IS_LINKED(&epi->txlink)) {
- /*
- * This is initialized in this way so that the default
- * behaviour of the reinjecting code will be to push back
- * the item inside the ready list.
- */
- epi->revents = epi->event.events;
-
- /* Link the ready item into the transfer list */
- list_add(&epi->txlink, txlist);
- nepi++;
-
- /*
- * Unlink the item from the ready list.
- */
- EP_LIST_DEL(&epi->rdllink);
- }
- }
-
- write_unlock_irqrestore(&ep->lock, flags);
-
- return nepi;
-}
-
-
-/*
* This function is called without holding the "ep->lock" since the call to
* __copy_to_user() might sleep, and also f_op->poll() might reenable the IRQ
* because of the way poll() is traditionally implemented in Linux.
*/
static int ep_send_events(struct eventpoll *ep, struct list_head *txlist,
- struct epoll_event __user *events)
+ struct epoll_event __user *events, int maxevents)
{
- int eventcnt = 0;
+ int eventcnt, error = -EFAULT, pwake = 0;
unsigned int revents;
- struct list_head *lnk;
+ unsigned long flags;
struct epitem *epi;
+ struct list_head injlist;
+
+ INIT_LIST_HEAD(&injlist);
/*
* We can loop without lock because this is a task private list.
- * The test done during the collection loop will guarantee us that
- * another task will not try to collect this file. Also, items
- * cannot vanish during the loop because we are holding "sem".
+ * We just splice'd out the ep->rdllist in ep_collect_ready_items().
+ * Items cannot vanish during the loop because we are holding "sem" in
+ * read.
*/
- list_for_each(lnk, txlist) {
- epi = list_entry(lnk, struct epitem, txlink);
+ for (eventcnt = 0; !list_empty(txlist) && eventcnt < maxevents;) {
+ epi = list_first_entry(txlist, struct epitem, rdllink);
+ prefetch(epi->rdllink.next);
/*
* Get the ready file event set. We can safely use the file
* guarantee that both the file and the item will not vanish.
*/
revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL);
+ revents &= epi->event.events;
/*
- * Set the return event set for the current file descriptor.
- * Note that only the task task was successfully able to link
- * the item to its "txlist" will write this field.
+ * Is the event mask intersect the caller-requested one,
+ * deliver the event to userspace. Again, we are holding
+ * "sem" in read, so no operations coming from userspace
+ * can change the item.
*/
- epi->revents = revents & epi->event.events;
-
- if (epi->revents) {
- if (__put_user(epi->revents,
+ if (revents) {
+ if (__put_user(revents,
&events[eventcnt].events) ||
__put_user(epi->event.data,
&events[eventcnt].data))
- return -EFAULT;
+ goto errxit;
if (epi->event.events & EPOLLONESHOT)
epi->event.events &= EP_PRIVATE_BITS;
eventcnt++;
}
- }
- return eventcnt;
-}
-
-
-/*
- * Walk through the transfer list we collected with ep_collect_ready_items()
- * and, if 1) the item is still "alive" 2) its event set is not empty 3) it's
- * not already linked, links it to the ready list. Same as above, we are holding
- * "sem" so items cannot vanish underneath our nose.
- */
-static void ep_reinject_items(struct eventpoll *ep, struct list_head *txlist)
-{
- int ricnt = 0, pwake = 0;
- unsigned long flags;
- struct epitem *epi;
-
- write_lock_irqsave(&ep->lock, flags);
-
- while (!list_empty(txlist)) {
- epi = list_entry(txlist->next, struct epitem, txlink);
-
- /* Unlink the current item from the transfer list */
- EP_LIST_DEL(&epi->txlink);
/*
- * If the item is no more linked to the interest set, we don't
- * have to push it inside the ready list because the following
- * ep_release_epitem() is going to drop it. Also, if the current
- * item is set to have an Edge Triggered behaviour, we don't have
- * to push it back either.
+ * This is tricky. We are holding the "sem" in read, and this
+ * means that the operations that can change the "linked" status
+ * of the epoll item (epi->rbn and epi->rdllink), cannot touch
+ * them. Also, since we are "linked" from a epi->rdllink POV
+ * (the item is linked to our transmission list we just
+ * spliced), the ep_poll_callback() cannot touch us either,
+ * because of the check present in there. Another parallel
+ * epoll_wait() will not get the same result set, since we
+ * spliced the ready list before. Note that list_del() still
+ * shows the item as linked to the test in ep_poll_callback().
*/
- if (EP_RB_LINKED(&epi->rbn) && !(epi->event.events & EPOLLET) &&
- (epi->revents & epi->event.events) && !EP_IS_LINKED(&epi->rdllink)) {
- list_add_tail(&epi->rdllink, &ep->rdllist);
- ricnt++;
+ list_del(&epi->rdllink);
+ if (!(epi->event.events & EPOLLET) &&
+ (revents & epi->event.events))
+ list_add_tail(&epi->rdllink, &injlist);
+ else {
+ /*
+ * Be sure the item is totally detached before re-init
+ * the list_head. After INIT_LIST_HEAD() is committed,
+ * the ep_poll_callback() can requeue the item again,
+ * but we don't care since we are already past it.
+ */
+ smp_mb();
+ INIT_LIST_HEAD(&epi->rdllink);
}
}
+ error = 0;
- if (ricnt) {
+ errxit:
+
+ /*
+ * If the re-injection list or the txlist are not empty, re-splice
+ * them to the ready list and do proper wakeups.
+ */
+ if (!list_empty(&injlist) || !list_empty(txlist)) {
+ write_lock_irqsave(&ep->lock, flags);
+
+ list_splice(txlist, &ep->rdllist);
+ list_splice(&injlist, &ep->rdllist);
/*
* Wake up ( if active ) both the eventpoll wait list and the ->poll()
* wait list.
*/
if (waitqueue_active(&ep->wq))
- wake_up(&ep->wq);
+ __wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE |
+ TASK_INTERRUPTIBLE);
if (waitqueue_active(&ep->poll_wait))
pwake++;
- }
- write_unlock_irqrestore(&ep->lock, flags);
+ write_unlock_irqrestore(&ep->lock, flags);
+ }
/* We have to call this outside the lock */
if (pwake)
ep_poll_safewake(&psw, &ep->poll_wait);
+
+ return eventcnt == 0 ? error: eventcnt;
}
static int ep_events_transfer(struct eventpoll *ep,
struct epoll_event __user *events, int maxevents)
{
- int eventcnt = 0;
+ int eventcnt;
+ unsigned long flags;
struct list_head txlist;
INIT_LIST_HEAD(&txlist);
*/
down_read(&ep->sem);
- /* Collect/extract ready items */
- if (ep_collect_ready_items(ep, &txlist, maxevents) > 0) {
- /* Build result set in userspace */
- eventcnt = ep_send_events(ep, &txlist, events);
+ /*
+ * Steal the ready list, and re-init the original one to the
+ * empty list.
+ */
+ write_lock_irqsave(&ep->lock, flags);
+ list_splice(&ep->rdllist, &txlist);
+ INIT_LIST_HEAD(&ep->rdllist);
+ write_unlock_irqrestore(&ep->lock, flags);
- /* Reinject ready items into the ready list */
- ep_reinject_items(ep, &txlist);
- }
+ /* Build result set in userspace */
+ eventcnt = ep_send_events(ep, &txlist, events, maxevents);
up_read(&ep->sem);
* and the overflow condition. The passed timeout is in milliseconds,
* that why (t * HZ) / 1000.
*/
- jtimeout = timeout == -1 || timeout > (MAX_SCHEDULE_TIMEOUT - 1000) / HZ ?
- MAX_SCHEDULE_TIMEOUT: (timeout * HZ + 999) / 1000;
+ jtimeout = (timeout < 0 || timeout >= EP_MAX_MSTIMEO) ?
+ MAX_SCHEDULE_TIMEOUT : (timeout * HZ + 999) / 1000;
retry:
write_lock_irqsave(&ep->lock, flags);
* ep_poll_callback() when events will become available.
*/
init_waitqueue_entry(&wait, current);
- add_wait_queue(&ep->wq, &wait);
+ __add_wait_queue(&ep->wq, &wait);
for (;;) {
/*
jtimeout = schedule_timeout(jtimeout);
write_lock_irqsave(&ep->lock, flags);
}
- remove_wait_queue(&ep->wq, &wait);
+ __remove_wait_queue(&ep->wq, &wait);
set_current_state(TASK_RUNNING);
}
return res;
}
-
static int eventpollfs_delete_dentry(struct dentry *dentry)
{
return 1;
}
-
static struct inode *ep_eventpoll_inode(void)
{
int error = -ENOMEM;
inode->i_uid = current->fsuid;
inode->i_gid = current->fsgid;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
- inode->i_blksize = PAGE_SIZE;
return inode;
eexit_1:
return ERR_PTR(error);
}
-
-static struct super_block *
+static int
eventpollfs_get_sb(struct file_system_type *fs_type, int flags,
- const char *dev_name, void *data)
+ const char *dev_name, void *data, struct vfsmount *mnt)
{
- return get_sb_pseudo(fs_type, "eventpoll:", NULL, EVENTPOLLFS_MAGIC);
+ return get_sb_pseudo(fs_type, "eventpoll:", NULL, EVENTPOLLFS_MAGIC,
+ mnt);
}
{
int error;
- init_MUTEX(&epsem);
+ mutex_init(&epmutex);
/* Initialize the structure used to perform safe poll wait head wake ups */
ep_poll_safewake_init(&psw);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff