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Message-ID: <send-serie.davidel@xmailserver.org.19972.1175650507.3>
Date: Tue, 03 Apr 2007 18:35:06 -0700
From: Davide Libenzi <davidel@...ilserver.org>
To: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Subject: [patch 3/3] epoll cleanups - epoll remove static pre-declarations and akpm-ize the code ...
Re-arrange epoll code to avoid static functions pre-declarations, and apply
akpm-filter on it.
Signed-off-by: Davide Libenzi <davidel@...ilserver.org>
- Davide
Index: linux-2.6.21-rc5.mm4/fs/eventpoll.c
===================================================================
--- linux-2.6.21-rc5.mm4.orig/fs/eventpoll.c 2007-04-03 18:33:40.000000000 -0700
+++ linux-2.6.21-rc5.mm4/fs/eventpoll.c 2007-04-03 18:33:42.000000000 -0700
@@ -32,7 +32,6 @@
#include <asm/uaccess.h>
#include <asm/atomic.h>
-
/*
* LOCKING:
* There are three level of locking required by epoll :
@@ -65,7 +64,6 @@
* a greater scalability.
*/
-
#define DEBUG_EPOLL 0
#if DEBUG_EPOLL > 0
@@ -95,7 +93,6 @@
#define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event))
-
struct epoll_filefd {
struct file *file;
int fd;
@@ -213,36 +210,6 @@
struct epitem *epi;
};
-
-
-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_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 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 void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi);
-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);
-static int ep_remove(struct eventpoll *ep, 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_send_events(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);
-static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
- int maxevents, long timeout);
-
/*
* This semaphore is used to serialize ep_free() and eventpoll_release_file().
*/
@@ -257,19 +224,6 @@
/* Slab cache used to allocate "struct eppoll_entry" */
static struct kmem_cache *pwq_cache __read_mostly;
-/* File callbacks that implement the eventpoll file behaviour */
-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,
@@ -338,7 +292,6 @@
spin_lock_init(&psw->lock);
}
-
/*
* Perform a safe wake up of the poll wait list. The problem is that
* with the new callback'd wake up system, it is possible that the
@@ -393,303 +346,265 @@
spin_unlock_irqrestore(&psw->lock, flags);
}
-
/*
- * 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
- * closed without being removed from the eventpoll interface.
+ * This function unregister poll callbacks from the associated file descriptor.
+ * Since this must be called without holding "ep->lock" the atomic exchange trick
+ * will protect us from multiple unregister.
*/
-void eventpoll_release_file(struct file *file)
+static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi)
{
- struct list_head *lsthead = &file->f_ep_links;
- struct eventpoll *ep;
- struct epitem *epi;
+ int nwait;
+ struct list_head *lsthead = &epi->pwqlist;
+ struct eppoll_entry *pwq;
- /*
- * We don't want to get "file->f_ep_lock" because it is not
- * necessary. It is not necessary because we're in the "struct file"
- * 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 "epmutex" because ep_remove() requires it when called
- * from anywhere but ep_free().
- */
- mutex_lock(&epmutex);
+ /* This is called without locks, so we need the atomic exchange */
+ nwait = xchg(&epi->nwait, 0);
- while (!list_empty(lsthead)) {
- epi = list_entry(lsthead->next, struct epitem, fllink);
+ if (nwait) {
+ while (!list_empty(lsthead)) {
+ pwq = list_entry(lsthead->next, struct eppoll_entry, llink);
- ep = epi->ep;
- list_del_init(&epi->fllink);
- down_write(&ep->sem);
- ep_remove(ep, epi);
- up_write(&ep->sem);
+ list_del_init(&pwq->llink);
+ remove_wait_queue(pwq->whead, &pwq->wait);
+ kmem_cache_free(pwq_cache, pwq);
+ }
}
-
- mutex_unlock(&epmutex);
}
-
/*
- * It opens an eventpoll file descriptor by suggesting a storage of "size"
- * 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).
+ * Unlink the "struct epitem" from all places it might have been hooked up.
+ * This function must be called with write IRQ lock on "ep->lock".
*/
-asmlinkage long sys_epoll_create(int size)
+static int ep_unlink(struct eventpoll *ep, struct epitem *epi)
{
- int error, fd = -1;
- struct eventpoll *ep;
- struct inode *inode;
- struct file *file;
+ int error;
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d)\n",
- current, size));
+ /*
+ * It can happen that this one is called for an item already unlinked.
+ * The check protect us from doing a double unlink ( crash ).
+ */
+ error = -ENOENT;
+ if (!ep_rb_linked(&epi->rbn))
+ goto error_return;
/*
- * Sanity check on the size parameter, and create the internal data
- * structure ( "struct eventpoll" ).
+ * Clear the event mask for the unlinked item. This will avoid item
+ * notifications to be sent after the unlink operation from inside
+ * the kernel->userspace event transfer loop.
*/
- error = -EINVAL;
- if (size <= 0 || (error = ep_alloc(&ep)) != 0)
- goto eexit_1;
+ epi->event.events = 0;
/*
- * Creates all the items needed to setup an eventpoll file. That is,
- * a file structure, and inode and a free file descriptor.
+ * At this point is safe to do the job, unlink the item from our rb-tree.
+ * This operation togheter with the above check closes the door to
+ * double unlinks.
*/
- error = anon_inode_getfd(&fd, &inode, &file, "[eventpoll]",
- &eventpoll_fops, ep);
- if (error)
- goto eexit_2;
+ ep_rb_erase(&epi->rbn, &ep->rbr);
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n",
- current, size, fd));
+ /*
+ * 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))
+ list_del_init(&epi->rdllink);
- return fd;
+ error = 0;
+error_return:
+
+ DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_unlink(%p, %p) = %d\n",
+ current, ep, epi->ffd.file, error));
-eexit_2:
- ep_free(ep);
- kfree(ep);
-eexit_1:
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n",
- current, size, error));
return error;
}
-
/*
- * The following function implements the controller interface for
- * the eventpoll file that enables the insertion/removal/change of
- * file descriptors inside the interest set. It represents
- * the kernel part of the user space epoll_ctl(2).
+ * Increment the usage count of the "struct epitem" making it sure
+ * that the user will have a valid pointer to reference.
*/
-asmlinkage long
-sys_epoll_ctl(int epfd, int op, int fd, struct epoll_event __user *event)
+static void ep_use_epitem(struct epitem *epi)
{
- int error;
- struct file *file, *tfile;
- struct eventpoll *ep;
- struct epitem *epi;
- struct epoll_event epds;
-
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_ctl(%d, %d, %d, %p)\n",
- current, epfd, op, fd, event));
-
- error = -EFAULT;
- if (ep_op_has_event(op) &&
- copy_from_user(&epds, event, sizeof(struct epoll_event)))
- goto eexit_1;
-
- /* Get the "struct file *" for the eventpoll file */
- error = -EBADF;
- file = fget(epfd);
- if (!file)
- goto eexit_1;
-
- /* Get the "struct file *" for the target file */
- tfile = fget(fd);
- if (!tfile)
- goto eexit_2;
+ atomic_inc(&epi->usecnt);
+}
- /* The target file descriptor must support poll */
- error = -EPERM;
- if (!tfile->f_op || !tfile->f_op->poll)
- goto eexit_3;
+/*
+ * Decrement ( release ) the usage count by signaling that the user
+ * has finished using the structure. It might lead to freeing the
+ * structure itself if the count goes to zero.
+ */
+static void ep_release_epitem(struct epitem *epi)
+{
+ if (atomic_dec_and_test(&epi->usecnt))
+ kmem_cache_free(epi_cache, epi);
+}
- /*
- * We have to check that the file structure underneath the file descriptor
- * the user passed to us _is_ an eventpoll file. And also we do not permit
- * adding an epoll file descriptor inside itself.
- */
- error = -EINVAL;
- if (file == tfile || !is_file_epoll(file))
- goto eexit_3;
+/*
+ * 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)
+{
+ int error;
+ unsigned long flags;
+ struct file *file = epi->ffd.file;
/*
- * At this point it is safe to assume that the "private_data" contains
- * our own data structure.
+ * Removes poll wait queue hooks. We _have_ to do this without holding
+ * the "ep->lock" otherwise a deadlock might occur. This because of the
+ * sequence of the lock acquisition. Here we do "ep->lock" then the wait
+ * queue head lock when unregistering the wait queue. The wakeup callback
+ * will run by holding the wait queue head lock and will call our callback
+ * that will try to get "ep->lock".
*/
- ep = file->private_data;
+ ep_unregister_pollwait(ep, epi);
- down_write(&ep->sem);
+ /* Remove the current item from the list of epoll hooks */
+ spin_lock(&file->f_ep_lock);
+ if (ep_is_linked(&epi->fllink))
+ list_del_init(&epi->fllink);
+ spin_unlock(&file->f_ep_lock);
- /* Try to lookup the file inside our RB tree */
- epi = ep_find(ep, tfile, fd);
+ /* We need to acquire the write IRQ lock before calling ep_unlink() */
+ write_lock_irqsave(&ep->lock, flags);
- error = -EINVAL;
- switch (op) {
- case EPOLL_CTL_ADD:
- if (!epi) {
- epds.events |= POLLERR | POLLHUP;
+ /* Really unlink the item from the RB tree */
+ error = ep_unlink(ep, epi);
- error = ep_insert(ep, &epds, tfile, fd);
- } else
- error = -EEXIST;
- break;
- case EPOLL_CTL_DEL:
- if (epi)
- error = ep_remove(ep, epi);
- else
- error = -ENOENT;
- break;
- case EPOLL_CTL_MOD:
- if (epi) {
- epds.events |= POLLERR | POLLHUP;
- error = ep_modify(ep, epi, &epds);
- } else
- error = -ENOENT;
- break;
- }
+ write_unlock_irqrestore(&ep->lock, flags);
- /*
- * The function ep_find() increments the usage count of the structure
- * so, if this is not NULL, we need to release it.
- */
- if (epi)
- ep_release_epitem(epi);
+ if (error)
+ goto error_return;
- up_write(&ep->sem);
+ /* At this point it is safe to free the eventpoll item */
+ ep_release_epitem(epi);
-eexit_3:
- fput(tfile);
-eexit_2:
- fput(file);
-eexit_1:
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_ctl(%d, %d, %d, %p) = %d\n",
- current, epfd, op, fd, event, error));
+ error = 0;
+error_return:
+ DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_remove(%p, %p) = %d\n",
+ current, ep, file, error));
return error;
}
-
-/*
- * Implement the event wait interface for the eventpoll file. It is the kernel
- * part of the user space epoll_wait(2).
- */
-asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events,
- int maxevents, int timeout)
+static void ep_free(struct eventpoll *ep)
{
- int error;
- struct file *file;
- struct eventpoll *ep;
-
- 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 || maxevents > EP_MAX_EVENTS)
- return -EINVAL;
+ struct rb_node *rbp;
+ struct epitem *epi;
- /* Verify that the area passed by the user is writeable */
- if (!access_ok(VERIFY_WRITE, events, maxevents * sizeof(struct epoll_event))) {
- error = -EFAULT;
- goto eexit_1;
- }
+ /* We need to release all tasks waiting for these file */
+ if (waitqueue_active(&ep->poll_wait))
+ ep_poll_safewake(&psw, &ep->poll_wait);
- /* Get the "struct file *" for the eventpoll file */
- error = -EBADF;
- file = fget(epfd);
- if (!file)
- goto eexit_1;
+ /*
+ * We need to lock this because we could be hit by
+ * eventpoll_release_file() while we're freeing the "struct eventpoll".
+ * 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 "epmutex" is sufficent here.
+ */
+ mutex_lock(&epmutex);
/*
- * We have to check that the file structure underneath the fd
- * the user passed to us _is_ an eventpoll file.
+ * Walks through the whole tree by unregistering poll callbacks.
*/
- error = -EINVAL;
- if (!is_file_epoll(file))
- goto eexit_2;
+ for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
+ epi = rb_entry(rbp, struct epitem, rbn);
+
+ ep_unregister_pollwait(ep, epi);
+ }
/*
- * At this point it is safe to assume that the "private_data" contains
- * our own data structure.
+ * 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 = file->private_data;
+ while ((rbp = rb_first(&ep->rbr)) != 0) {
+ epi = rb_entry(rbp, struct epitem, rbn);
+ ep_remove(ep, epi);
+ }
- /* Time to fish for events ... */
- error = ep_poll(ep, events, maxevents, timeout);
+ mutex_unlock(&epmutex);
+}
-eexit_2:
- fput(file);
-eexit_1:
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_wait(%d, %p, %d, %d) = %d\n",
- current, epfd, events, maxevents, timeout, error));
+static int ep_eventpoll_release(struct inode *inode, struct file *file)
+{
+ struct eventpoll *ep = file->private_data;
- return error;
+ if (ep) {
+ ep_free(ep);
+ kfree(ep);
+ }
+
+ DNPRINTK(3, (KERN_INFO "[%p] eventpoll: close() ep=%p\n", current, ep));
+ return 0;
}
+static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait)
+{
+ unsigned int pollflags = 0;
+ unsigned long flags;
+ struct eventpoll *ep = file->private_data;
-#ifdef TIF_RESTORE_SIGMASK
+ /* Insert inside our poll wait queue */
+ poll_wait(file, &ep->poll_wait, wait);
+
+ /* Check our condition */
+ read_lock_irqsave(&ep->lock, flags);
+ if (!list_empty(&ep->rdllist))
+ pollflags = POLLIN | POLLRDNORM;
+ read_unlock_irqrestore(&ep->lock, flags);
+
+ return pollflags;
+}
+
+/* File callbacks that implement the eventpoll file behaviour */
+static const struct file_operations eventpoll_fops = {
+ .release = ep_eventpoll_release,
+ .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;
+}
/*
- * Implement the event wait interface for the eventpoll file. It is the kernel
- * part of the user space epoll_pwait(2).
+ * 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
+ * closed without being removed from the eventpoll interface.
*/
-asmlinkage long sys_epoll_pwait(int epfd, struct epoll_event __user *events,
- int maxevents, int timeout, const sigset_t __user *sigmask,
- size_t sigsetsize)
+void eventpoll_release_file(struct file *file)
{
- int error;
- sigset_t ksigmask, sigsaved;
+ struct list_head *lsthead = &file->f_ep_links;
+ struct eventpoll *ep;
+ struct epitem *epi;
/*
- * If the caller wants a certain signal mask to be set during the wait,
- * we apply it here.
+ * We don't want to get "file->f_ep_lock" because it is not
+ * necessary. It is not necessary because we're in the "struct file"
+ * 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 "epmutex" because ep_remove() requires it when called
+ * from anywhere but ep_free().
*/
- 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);
- }
+ mutex_lock(&epmutex);
- error = sys_epoll_wait(epfd, events, maxevents, timeout);
+ while (!list_empty(lsthead)) {
+ epi = list_entry(lsthead->next, struct epitem, fllink);
- /*
- * 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);
+ ep = epi->ep;
+ list_del_init(&epi->fllink);
+ down_write(&ep->sem);
+ ep_remove(ep, epi);
+ up_write(&ep->sem);
}
- return error;
+ mutex_unlock(&epmutex);
}
-#endif /* #ifdef TIF_RESTORE_SIGMASK */
-
-
static int ep_alloc(struct eventpoll **pep)
{
struct eventpoll *ep = kzalloc(sizeof(*ep), GFP_KERNEL);
@@ -711,50 +626,6 @@
return 0;
}
-
-static void ep_free(struct eventpoll *ep)
-{
- struct rb_node *rbp;
- struct epitem *epi;
-
- /* We need to release all tasks waiting for these file */
- if (waitqueue_active(&ep->poll_wait))
- ep_poll_safewake(&psw, &ep->poll_wait);
-
- /*
- * We need to lock this because we could be hit by
- * eventpoll_release_file() while we're freeing the "struct eventpoll".
- * 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 "epmutex" is sufficent here.
- */
- mutex_lock(&epmutex);
-
- /*
- * Walks through the whole tree by unregistering poll callbacks.
- */
- for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
- epi = rb_entry(rbp, struct epitem, rbn);
-
- ep_unregister_pollwait(ep, epi);
- }
-
- /*
- * 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".
- */
- while ((rbp = rb_first(&ep->rbr)) != 0) {
- epi = rb_entry(rbp, struct epitem, rbn);
- ep_remove(ep, epi);
- }
-
- mutex_unlock(&epmutex);
-}
-
-
/*
* Search the file inside the eventpoll tree. It add usage count to
* the returned item, so the caller must call ep_release_epitem()
@@ -791,30 +662,58 @@
return epir;
}
-
/*
- * Increment the usage count of the "struct epitem" making it sure
- * that the user will have a valid pointer to reference.
+ * This is the callback that is passed to the wait queue wakeup
+ * machanism. It is called by the stored file descriptors when they
+ * have events to report.
*/
-static void ep_use_epitem(struct epitem *epi)
+static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *key)
{
+ int pwake = 0;
+ unsigned long flags;
+ struct epitem *epi = ep_item_from_wait(wait);
+ struct eventpoll *ep = epi->ep;
- atomic_inc(&epi->usecnt);
-}
+ DNPRINTK(3, (KERN_INFO "[%p] eventpoll: poll_callback(%p) epi=%p ep=%p\n",
+ current, epi->ffd.file, epi, ep));
+ write_lock_irqsave(&ep->lock, flags);
-/*
- * Decrement ( release ) the usage count by signaling that the user
- * has finished using the structure. It might lead to freeing the
- * structure itself if the count goes to zero.
- */
-static void ep_release_epitem(struct epitem *epi)
-{
+ /*
+ * If the event mask does not contain any poll(2) event, we consider the
+ * descriptor to be disabled. This condition is likely the effect of the
+ * EPOLLONESHOT bit that disables the descriptor when an event is received,
+ * until the next EPOLL_CTL_MOD will be issued.
+ */
+ if (!(epi->event.events & ~EP_PRIVATE_BITS))
+ goto is_disabled;
- if (atomic_dec_and_test(&epi->usecnt))
- kmem_cache_free(epi_cache, epi);
-}
+ /* If this file is already in the ready list we exit soon */
+ if (ep_is_linked(&epi->rdllink))
+ goto is_linked;
+
+ list_add_tail(&epi->rdllink, &ep->rdllist);
+
+is_linked:
+ /*
+ * Wake up ( if active ) both the eventpoll wait list and the ->poll()
+ * wait list.
+ */
+ if (waitqueue_active(&ep->wq))
+ __wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE |
+ TASK_INTERRUPTIBLE);
+ if (waitqueue_active(&ep->poll_wait))
+ pwake++;
+
+is_disabled:
+ write_unlock_irqrestore(&ep->lock, flags);
+ /* We have to call this outside the lock */
+ if (pwake)
+ ep_poll_safewake(&psw, &ep->poll_wait);
+
+ return 1;
+}
/*
* This is the callback that is used to add our wait queue to the
@@ -839,7 +738,6 @@
}
}
-
static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
{
int kcmp;
@@ -859,7 +757,6 @@
rb_insert_color(&epi->rbn, &ep->rbr);
}
-
static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
struct file *tfile, int fd)
{
@@ -870,7 +767,7 @@
error = -ENOMEM;
if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL)))
- goto eexit_1;
+ goto error_return;
/* Item initialization follow here ... */
ep_rb_initnode(&epi->rbn);
@@ -900,7 +797,7 @@
* high memory pressure.
*/
if (epi->nwait < 0)
- goto eexit_2;
+ goto error_unregister;
/* Add the current item to the list of active epoll hook for this file */
spin_lock(&tfile->f_ep_lock);
@@ -935,7 +832,7 @@
return 0;
-eexit_2:
+error_unregister:
ep_unregister_pollwait(ep, epi);
/*
@@ -948,11 +845,10 @@
write_unlock_irqrestore(&ep->lock, flags);
kmem_cache_free(epi_cache, epi);
-eexit_1:
+error_return:
return error;
}
-
/*
* Modify the interest event mask by dropping an event if the new mask
* has a match in the current file status.
@@ -1000,231 +896,21 @@
if (waitqueue_active(&ep->wq))
__wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE |
TASK_INTERRUPTIBLE);
- if (waitqueue_active(&ep->poll_wait))
- pwake++;
- }
- }
- }
-
- write_unlock_irqrestore(&ep->lock, flags);
-
- /* We have to call this outside the lock */
- if (pwake)
- ep_poll_safewake(&psw, &ep->poll_wait);
-
- return 0;
-}
-
-
-/*
- * This function unregister poll callbacks from the associated file descriptor.
- * Since this must be called without holding "ep->lock" the atomic exchange trick
- * will protect us from multiple unregister.
- */
-static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi)
-{
- int nwait;
- struct list_head *lsthead = &epi->pwqlist;
- struct eppoll_entry *pwq;
-
- /* This is called without locks, so we need the atomic exchange */
- nwait = xchg(&epi->nwait, 0);
-
- if (nwait) {
- while (!list_empty(lsthead)) {
- pwq = list_entry(lsthead->next, struct eppoll_entry, llink);
-
- list_del_init(&pwq->llink);
- remove_wait_queue(pwq->whead, &pwq->wait);
- kmem_cache_free(pwq_cache, pwq);
- }
- }
-}
-
-
-/*
- * Unlink the "struct epitem" from all places it might have been hooked up.
- * This function must be called with write IRQ lock on "ep->lock".
- */
-static int ep_unlink(struct eventpoll *ep, struct epitem *epi)
-{
- int error;
-
- /*
- * It can happen that this one is called for an item already unlinked.
- * The check protect us from doing a double unlink ( crash ).
- */
- error = -ENOENT;
- if (!ep_rb_linked(&epi->rbn))
- goto eexit_1;
-
- /*
- * Clear the event mask for the unlinked item. This will avoid item
- * notifications to be sent after the unlink operation from inside
- * the kernel->userspace event transfer loop.
- */
- epi->event.events = 0;
-
- /*
- * At this point is safe to do the job, unlink the item from our rb-tree.
- * This operation togheter with the above check closes the door to
- * double unlinks.
- */
- 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))
- list_del_init(&epi->rdllink);
-
- error = 0;
-eexit_1:
-
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_unlink(%p, %p) = %d\n",
- current, ep, epi->ffd.file, error));
-
- return error;
-}
-
-
-/*
- * 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)
-{
- int error;
- unsigned long flags;
- struct file *file = epi->ffd.file;
-
- /*
- * Removes poll wait queue hooks. We _have_ to do this without holding
- * the "ep->lock" otherwise a deadlock might occur. This because of the
- * sequence of the lock acquisition. Here we do "ep->lock" then the wait
- * queue head lock when unregistering the wait queue. The wakeup callback
- * will run by holding the wait queue head lock and will call our callback
- * that will try to get "ep->lock".
- */
- ep_unregister_pollwait(ep, epi);
-
- /* Remove the current item from the list of epoll hooks */
- spin_lock(&file->f_ep_lock);
- 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 RB tree */
- error = ep_unlink(ep, epi);
-
- write_unlock_irqrestore(&ep->lock, flags);
-
- if (error)
- goto eexit_1;
-
- /* At this point it is safe to free the eventpoll item */
- ep_release_epitem(epi);
-
- error = 0;
-eexit_1:
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_remove(%p, %p) = %d\n",
- current, ep, file, error));
-
- return error;
-}
-
-
-/*
- * This is the callback that is passed to the wait queue wakeup
- * machanism. It is called by the stored file descriptors when they
- * have events to report.
- */
-static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *key)
-{
- int pwake = 0;
- unsigned long flags;
- 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->ffd.file, epi, ep));
-
- write_lock_irqsave(&ep->lock, flags);
-
- /*
- * If the event mask does not contain any poll(2) event, we consider the
- * descriptor to be disabled. This condition is likely the effect of the
- * EPOLLONESHOT bit that disables the descriptor when an event is received,
- * until the next EPOLL_CTL_MOD will be issued.
- */
- if (!(epi->event.events & ~EP_PRIVATE_BITS))
- goto is_disabled;
-
- /* If this file is already in the ready list we exit soon */
- if (ep_is_linked(&epi->rdllink))
- goto is_linked;
-
- list_add_tail(&epi->rdllink, &ep->rdllist);
-
-is_linked:
- /*
- * Wake up ( if active ) both the eventpoll wait list and the ->poll()
- * wait list.
- */
- if (waitqueue_active(&ep->wq))
- __wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE |
- TASK_INTERRUPTIBLE);
- if (waitqueue_active(&ep->poll_wait))
- pwake++;
-
-is_disabled:
- write_unlock_irqrestore(&ep->lock, flags);
-
- /* We have to call this outside the lock */
- if (pwake)
- ep_poll_safewake(&psw, &ep->poll_wait);
-
- return 1;
-}
-
-
-static int ep_eventpoll_close(struct inode *inode, struct file *file)
-{
- struct eventpoll *ep = file->private_data;
-
- if (ep) {
- ep_free(ep);
- kfree(ep);
- }
-
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: close() ep=%p\n", current, ep));
- return 0;
-}
-
-
-static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait)
-{
- unsigned int pollflags = 0;
- unsigned long flags;
- struct eventpoll *ep = file->private_data;
+ if (waitqueue_active(&ep->poll_wait))
+ pwake++;
+ }
+ }
+ }
- /* Insert inside our poll wait queue */
- poll_wait(file, &ep->poll_wait, wait);
+ write_unlock_irqrestore(&ep->lock, flags);
- /* Check our condition */
- read_lock_irqsave(&ep->lock, flags);
- if (!list_empty(&ep->rdllist))
- pollflags = POLLIN | POLLRDNORM;
- read_unlock_irqrestore(&ep->lock, flags);
+ /* We have to call this outside the lock */
+ if (pwake)
+ ep_poll_safewake(&psw, &ep->poll_wait);
- return pollflags;
+ return 0;
}
-
/*
* 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
@@ -1336,7 +1022,6 @@
return eventcnt == 0 ? error: eventcnt;
}
-
/*
* Perform the transfer of events to user space.
*/
@@ -1372,7 +1057,6 @@
return eventcnt;
}
-
static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
int maxevents, long timeout)
{
@@ -1442,6 +1126,260 @@
return res;
}
+/*
+ * It opens an eventpoll file descriptor by suggesting a storage of "size"
+ * 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 long sys_epoll_create(int size)
+{
+ 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, and create the internal data
+ * structure ( "struct eventpoll" ).
+ */
+ error = -EINVAL;
+ if (size <= 0 || (error = ep_alloc(&ep)) != 0)
+ goto error_return;
+
+ /*
+ * Creates all the items needed to setup an eventpoll file. That is,
+ * a file structure, and inode and a free file descriptor.
+ */
+ error = anon_inode_getfd(&fd, &inode, &file, "[eventpoll]",
+ &eventpoll_fops, ep);
+ if (error)
+ goto error_free;
+
+ DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n",
+ current, size, fd));
+
+ return fd;
+
+error_free:
+ ep_free(ep);
+ kfree(ep);
+error_return:
+ DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n",
+ current, size, error));
+ return error;
+}
+
+/*
+ * The following function implements the controller interface for
+ * the eventpoll file that enables the insertion/removal/change of
+ * file descriptors inside the interest set. It represents
+ * the kernel part of the user space epoll_ctl(2).
+ */
+asmlinkage long sys_epoll_ctl(int epfd, int op, int fd,
+ struct epoll_event __user *event)
+{
+ int error;
+ struct file *file, *tfile;
+ struct eventpoll *ep;
+ struct epitem *epi;
+ struct epoll_event epds;
+
+ DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_ctl(%d, %d, %d, %p)\n",
+ current, epfd, op, fd, event));
+
+ error = -EFAULT;
+ if (ep_op_has_event(op) &&
+ copy_from_user(&epds, event, sizeof(struct epoll_event)))
+ goto error_return;
+
+ /* Get the "struct file *" for the eventpoll file */
+ error = -EBADF;
+ file = fget(epfd);
+ if (!file)
+ goto error_return;
+
+ /* Get the "struct file *" for the target file */
+ tfile = fget(fd);
+ if (!tfile)
+ goto error_fput;
+
+ /* The target file descriptor must support poll */
+ error = -EPERM;
+ if (!tfile->f_op || !tfile->f_op->poll)
+ goto error_tgt_fput;
+
+ /*
+ * We have to check that the file structure underneath the file descriptor
+ * the user passed to us _is_ an eventpoll file. And also we do not permit
+ * adding an epoll file descriptor inside itself.
+ */
+ error = -EINVAL;
+ if (file == tfile || !is_file_epoll(file))
+ goto error_tgt_fput;
+
+ /*
+ * At this point it is safe to assume that the "private_data" contains
+ * our own data structure.
+ */
+ ep = file->private_data;
+
+ down_write(&ep->sem);
+
+ /* Try to lookup the file inside our RB tree */
+ epi = ep_find(ep, tfile, fd);
+
+ error = -EINVAL;
+ switch (op) {
+ case EPOLL_CTL_ADD:
+ if (!epi) {
+ epds.events |= POLLERR | POLLHUP;
+
+ error = ep_insert(ep, &epds, tfile, fd);
+ } else
+ error = -EEXIST;
+ break;
+ case EPOLL_CTL_DEL:
+ if (epi)
+ error = ep_remove(ep, epi);
+ else
+ error = -ENOENT;
+ break;
+ case EPOLL_CTL_MOD:
+ if (epi) {
+ epds.events |= POLLERR | POLLHUP;
+ error = ep_modify(ep, epi, &epds);
+ } else
+ error = -ENOENT;
+ break;
+ }
+ /*
+ * The function ep_find() increments the usage count of the structure
+ * so, if this is not NULL, we need to release it.
+ */
+ if (epi)
+ ep_release_epitem(epi);
+ up_write(&ep->sem);
+
+error_tgt_fput:
+ fput(tfile);
+error_fput:
+ fput(file);
+error_return:
+ DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_ctl(%d, %d, %d, %p) = %d\n",
+ current, epfd, op, fd, event, error));
+
+ return error;
+}
+
+/*
+ * Implement the event wait interface for the eventpoll file. It is the kernel
+ * part of the user space epoll_wait(2).
+ */
+asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events,
+ int maxevents, int timeout)
+{
+ int error;
+ struct file *file;
+ struct eventpoll *ep;
+
+ 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 || maxevents > EP_MAX_EVENTS)
+ return -EINVAL;
+
+ /* Verify that the area passed by the user is writeable */
+ if (!access_ok(VERIFY_WRITE, events, maxevents * sizeof(struct epoll_event))) {
+ error = -EFAULT;
+ goto error_return;
+ }
+
+ /* Get the "struct file *" for the eventpoll file */
+ error = -EBADF;
+ file = fget(epfd);
+ if (!file)
+ goto error_return;
+
+ /*
+ * We have to check that the file structure underneath the fd
+ * the user passed to us _is_ an eventpoll file.
+ */
+ error = -EINVAL;
+ if (!is_file_epoll(file))
+ goto error_fput;
+
+ /*
+ * At this point it is safe to assume that the "private_data" contains
+ * our own data structure.
+ */
+ ep = file->private_data;
+
+ /* Time to fish for events ... */
+ error = ep_poll(ep, events, maxevents, timeout);
+
+error_fput:
+ fput(file);
+error_return:
+ DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_wait(%d, %p, %d, %d) = %d\n",
+ current, epfd, events, maxevents, timeout, error));
+
+ return error;
+}
+
+#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 */
+
static int __init eventpoll_init(void)
{
mutex_init(&epmutex);
-
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