Skip to content

L
linux
Commit 7699acd1 authored by Davide Libenzi's avatar Davide Libenzi Committed by Linus Torvalds
Browse files
Options

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: default avatarDavide Libenzi <davidel@xmailserver.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent cea69241
Show whitespace changes
Inline Side-by-side
Showing with 499 additions and 561 deletions
fs/eventpoll.c
View file @ 7699acd1
...@@ -41,7 +41,6 @@ ...@@ -41,7 +41,6 @@
#include <asm/atomic.h> #include <asm/atomic.h>
#include <asm/semaphore.h> #include <asm/semaphore.h>
/* /*
* LOCKING: * LOCKING:
* There are three level of locking required by epoll : * There are three level of locking required by epoll :
...@@ -74,7 +73,6 @@ ...@@ -74,7 +73,6 @@
* a greater scalability. * a greater scalability.
*/ */
#define DEBUG_EPOLL 0 #define DEBUG_EPOLL 0
#if DEBUG_EPOLL > 0 #if DEBUG_EPOLL > 0
...@@ -104,7 +102,6 @@ ...@@ -104,7 +102,6 @@
#define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event)) #define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event))
struct epoll_filefd { struct epoll_filefd {
struct file *file; struct file *file;
int fd; int fd;
...@@ -222,36 +219,6 @@ struct ep_pqueue { ...@@ -222,36 +219,6 @@ struct ep_pqueue {
struct epitem *epi; 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(). * This semaphore is used to serialize ep_free() and eventpoll_release_file().
*/ */
...@@ -266,19 +233,6 @@ static struct kmem_cache *epi_cache __read_mostly; ...@@ -266,19 +233,6 @@ static struct kmem_cache *epi_cache __read_mostly;
/* Slab cache used to allocate "struct eppoll_entry" */ /* Slab cache used to allocate "struct eppoll_entry" */
static struct kmem_cache *pwq_cache __read_mostly; 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 */ /* Setup the structure that is used as key for the rb-tree */
static inline void ep_set_ffd(struct epoll_filefd *ffd, static inline void ep_set_ffd(struct epoll_filefd *ffd,
...@@ -347,7 +301,6 @@ static void ep_poll_safewake_init(struct poll_safewake *psw) ...@@ -347,7 +301,6 @@ static void ep_poll_safewake_init(struct poll_safewake *psw)
spin_lock_init(&psw->lock); spin_lock_init(&psw->lock);
} }
/* /*
* Perform a safe wake up of the poll wait list. The problem is that * 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 * with the new callback'd wake up system, it is possible that the
...@@ -402,303 +355,265 @@ static void ep_poll_safewake(struct poll_safewake *psw, wait_queue_head_t *wq) ...@@ -402,303 +355,265 @@ static void ep_poll_safewake(struct poll_safewake *psw, wait_queue_head_t *wq)
spin_unlock_irqrestore(&psw->lock, flags); spin_unlock_irqrestore(&psw->lock, flags);
} }
/* /*
* This is called from eventpoll_release() to unlink files from the eventpoll * This function unregister poll callbacks from the associated file descriptor.
* interface. We need to have this facility to cleanup correctly files that are * Since this must be called without holding "ep->lock" the atomic exchange trick
* closed without being removed from the eventpoll interface. * 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; int nwait;
struct eventpoll *ep; struct list_head *lsthead = &epi->pwqlist;
struct epitem *epi; struct eppoll_entry *pwq;
/* /* This is called without locks, so we need the atomic exchange */
* We don't want to get "file->f_ep_lock" because it is not nwait = xchg(&epi->nwait, 0);
* 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);
if (nwait) {
while (!list_empty(lsthead)) { while (!list_empty(lsthead)) {
epi = list_first_entry(lsthead, struct epitem, fllink); pwq = list_first_entry(lsthead, struct eppoll_entry, llink);
ep = epi->ep; list_del_init(&pwq->llink);
list_del_init(&epi->fllink); remove_wait_queue(pwq->whead, &pwq->wait);
down_write(&ep->sem); kmem_cache_free(pwq_cache, pwq);
ep_remove(ep, epi); }
up_write(&ep->sem);
} }
mutex_unlock(&epmutex);
} }
/* /*
* It opens an eventpoll file descriptor by suggesting a storage of "size" * Unlink the "struct epitem" from all places it might have been hooked up.
* file descriptors. The size parameter is just an hint about how to size * This function must be called with write IRQ lock on "ep->lock".
* 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) static int ep_unlink(struct eventpoll *ep, struct epitem *epi)
{ {
int error, fd = -1; int error;
struct eventpoll *ep;
struct inode *inode;
struct file *file;
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 * Clear the event mask for the unlinked item. This will avoid item
* structure ( "struct eventpoll" ). * notifications to be sent after the unlink operation from inside
* the kernel->userspace event transfer loop.
*/ */
error = -EINVAL; epi->event.events = 0;
if (size <= 0 || (error = ep_alloc(&ep)) != 0)
goto eexit_1;
/* /*
* Creates all the items needed to setup an eventpoll file. That is, * At this point is safe to do the job, unlink the item from our rb-tree.
* a file structure, and inode and a free file descriptor. * This operation togheter with the above check closes the door to
* double unlinks.
*/ */
error = anon_inode_getfd(&fd, &inode, &file, "[eventpoll]", ep_rb_erase(&epi->rbn, &ep->rbr);
&eventpoll_fops, ep);
if (error)
goto eexit_2;
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; return error;
} }
/* /*
* The following function implements the controller interface for * Increment the usage count of the "struct epitem" making it sure
* the eventpoll file that enables the insertion/removal/change of * that the user will have a valid pointer to reference.
* file descriptors inside the interest set. It represents
* the kernel part of the user space epoll_ctl(2).
*/ */
asmlinkage long static void ep_use_epitem(struct epitem *epi)
sys_epoll_ctl(int epfd, int op, int fd, struct epoll_event __user *event)
{ {
int error; atomic_inc(&epi->usecnt);
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;
/* The target file descriptor must support poll */ /*
error = -EPERM; * Decrement ( release ) the usage count by signaling that the user
if (!tfile->f_op || !tfile->f_op->poll) * has finished using the structure. It might lead to freeing the
goto eexit_3; * 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 * Removes a "struct epitem" from the eventpoll RB tree and deallocates
* the user passed to us _is_ an eventpoll file. And also we do not permit * all the associated resources.
* adding an epoll file descriptor inside itself.
*/ */
error = -EINVAL; static int ep_remove(struct eventpoll *ep, struct epitem *epi)
if (file == tfile || !is_file_epoll(file)) {
goto eexit_3; int error;
unsigned long flags;
struct file *file = epi->ffd.file;
/* /*
* At this point it is safe to assume that the "private_data" contains * Removes poll wait queue hooks. We _have_ to do this without holding
* our own data structure. * 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 */ /* We need to acquire the write IRQ lock before calling ep_unlink() */
epi = ep_find(ep, tfile, fd); write_lock_irqsave(&ep->lock, flags);
error = -EINVAL; /* Really unlink the item from the RB tree */
switch (op) { error = ep_unlink(ep, epi);
case EPOLL_CTL_ADD:
if (!epi) {
epds.events |= POLLERR | POLLHUP;
error = ep_insert(ep, &epds, tfile, fd); write_unlock_irqrestore(&ep->lock, flags);
} 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;
}
/* if (error)
* The function ep_find() increments the usage count of the structure goto error_return;
* so, if this is not NULL, we need to release it.
*/
if (epi)
ep_release_epitem(epi);
up_write(&ep->sem); /* At this point it is safe to free the eventpoll item */
ep_release_epitem(epi);
eexit_3: error = 0;
fput(tfile); error_return:
eexit_2: DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_remove(%p, %p) = %d\n",
fput(file); current, ep, file, error));
eexit_1:
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_ctl(%d, %d, %d, %p) = %d\n",
current, epfd, op, fd, event, error));
return error; return error;
} }
static void ep_free(struct eventpoll *ep)
/*
* 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 rb_node *rbp;
struct file *file; struct epitem *epi;
struct eventpoll *ep;
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_wait(%d, %p, %d, %d)\n", /* We need to release all tasks waiting for these file */
current, epfd, events, maxevents, timeout)); if (waitqueue_active(&ep->poll_wait))
ep_poll_safewake(&psw, &ep->poll_wait);
/* 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 eexit_1;
}
/* Get the "struct file *" for the eventpoll file */ /*
error = -EBADF; * We need to lock this because we could be hit by
file = fget(epfd); * eventpoll_release_file() while we're freeing the "struct eventpoll".
if (!file) * We do not need to hold "ep->sem" here because the epoll file
goto eexit_1; * 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 * Walks through the whole tree by unregistering poll callbacks.
* the user passed to us _is_ an eventpoll file.
*/ */
error = -EINVAL; for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
if (!is_file_epoll(file)) epi = rb_entry(rbp, struct epitem, rbn);
goto eexit_2;
ep_unregister_pollwait(ep, epi);
}
/* /*
* At this point it is safe to assume that the "private_data" contains * Walks through the whole tree by freeing each "struct epitem". At this
* our own data structure. * 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 ... */ mutex_unlock(&epmutex);
error = ep_poll(ep, events, maxevents, timeout); }
eexit_2: static int ep_eventpoll_release(struct inode *inode, struct file *file)
fput(file); {
eexit_1: struct eventpoll *ep = file->private_data;
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_wait(%d, %p, %d, %d) = %d\n",
current, epfd, events, maxevents, timeout, error));
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 * This is called from eventpoll_release() to unlink files from the eventpoll
* part of the user space epoll_pwait(2). * 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, void eventpoll_release_file(struct file *file)
int maxevents, int timeout, const sigset_t __user *sigmask,
size_t sigsetsize)
{ {
int error; struct list_head *lsthead = &file->f_ep_links;
sigset_t ksigmask, sigsaved; struct eventpoll *ep;
struct epitem *epi;
/* /*
* If the caller wants a certain signal mask to be set during the wait, * We don't want to get "file->f_ep_lock" because it is not
* we apply it here. * 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) { mutex_lock(&epmutex);
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); while (!list_empty(lsthead)) {
epi = list_first_entry(lsthead, struct epitem, fllink);
/* ep = epi->ep;
* If we changed the signal mask, we need to restore the original one. list_del_init(&epi->fllink);
* In case we've got a signal while waiting, we do not restore the down_write(&ep->sem);
* signal mask yet, and we allow do_signal() to deliver the signal on ep_remove(ep, epi);
* the way back to userspace, before the signal mask is restored. up_write(&ep->sem);
*/
if (sigmask) {
if (error == -EINTR) {
memcpy(&current->saved_sigmask, &sigsaved,
sizeof(sigsaved));
set_thread_flag(TIF_RESTORE_SIGMASK);
} else
sigprocmask(SIG_SETMASK, &sigsaved, NULL);
} }
return error; mutex_unlock(&epmutex);
} }
#endif /* #ifdef TIF_RESTORE_SIGMASK */
static int ep_alloc(struct eventpoll **pep) static int ep_alloc(struct eventpoll **pep)
{ {
struct eventpoll *ep = kzalloc(sizeof(*ep), GFP_KERNEL); struct eventpoll *ep = kzalloc(sizeof(*ep), GFP_KERNEL);
...@@ -720,50 +635,6 @@ static int ep_alloc(struct eventpoll **pep) ...@@ -720,50 +635,6 @@ static int ep_alloc(struct eventpoll **pep)
return 0; 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 * Search the file inside the eventpoll tree. It add usage count to
* the returned item, so the caller must call ep_release_epitem() * the returned item, so the caller must call ep_release_epitem()
...@@ -800,30 +671,58 @@ static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd) ...@@ -800,30 +671,58 @@ static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd)
return epir; return epir;
} }
/* /*
* Increment the usage count of the "struct epitem" making it sure * This is the callback that is passed to the wait queue wakeup
* that the user will have a valid pointer to reference. * 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 * If the event mask does not contain any poll(2) event, we consider the
* has finished using the structure. It might lead to freeing the * descriptor to be disabled. This condition is likely the effect of the
* structure itself if the count goes to zero. * EPOLLONESHOT bit that disables the descriptor when an event is received,
* until the next EPOLL_CTL_MOD will be issued.
*/ */
static void ep_release_epitem(struct epitem *epi) if (!(epi->event.events & ~EP_PRIVATE_BITS))
{ goto is_disabled;
if (atomic_dec_and_test(&epi->usecnt)) /* If this file is already in the ready list we exit soon */
kmem_cache_free(epi_cache, epi); 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 * This is the callback that is used to add our wait queue to the
...@@ -848,7 +747,6 @@ static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, ...@@ -848,7 +747,6 @@ static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
} }
} }
static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi) static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
{ {
int kcmp; int kcmp;
...@@ -868,7 +766,6 @@ static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi) ...@@ -868,7 +766,6 @@ static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
rb_insert_color(&epi->rbn, &ep->rbr); rb_insert_color(&epi->rbn, &ep->rbr);
} }
static int ep_insert(struct eventpoll *ep, struct epoll_event *event, static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
struct file *tfile, int fd) struct file *tfile, int fd)
{ {
...@@ -879,7 +776,7 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event, ...@@ -879,7 +776,7 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
error = -ENOMEM; error = -ENOMEM;
if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL))) if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL)))
goto eexit_1; goto error_return;
/* Item initialization follow here ... */ /* Item initialization follow here ... */
ep_rb_initnode(&epi->rbn); ep_rb_initnode(&epi->rbn);
...@@ -909,7 +806,7 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event, ...@@ -909,7 +806,7 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
* high memory pressure. * high memory pressure.
*/ */
if (epi->nwait < 0) if (epi->nwait < 0)
goto eexit_2; goto error_unregister;
/* Add the current item to the list of active epoll hook for this file */ /* Add the current item to the list of active epoll hook for this file */
spin_lock(&tfile->f_ep_lock); spin_lock(&tfile->f_ep_lock);
...@@ -944,7 +841,7 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event, ...@@ -944,7 +841,7 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
return 0; return 0;
eexit_2: error_unregister:
ep_unregister_pollwait(ep, epi); ep_unregister_pollwait(ep, epi);
/* /*
...@@ -957,11 +854,10 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event, ...@@ -957,11 +854,10 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
write_unlock_irqrestore(&ep->lock, flags); write_unlock_irqrestore(&ep->lock, flags);
kmem_cache_free(epi_cache, epi); kmem_cache_free(epi_cache, epi);
eexit_1: error_return:
return error; return error;
} }
/* /*
* Modify the interest event mask by dropping an event if the new mask * Modify the interest event mask by dropping an event if the new mask
* has a match in the current file status. * has a match in the current file status.
...@@ -1024,216 +920,6 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_even ...@@ -1024,216 +920,6 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_even
return 0; 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_first_entry(lsthead, 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;
/* 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;
}
/* /*
* This function is called without holding the "ep->lock" since the call to * 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 * __copy_to_user() might sleep, and also f_op->poll() might reenable the IRQ
...@@ -1345,7 +1031,6 @@ static int ep_send_events(struct eventpoll *ep, struct list_head *txlist, ...@@ -1345,7 +1031,6 @@ static int ep_send_events(struct eventpoll *ep, struct list_head *txlist,
return eventcnt == 0 ? error: eventcnt; return eventcnt == 0 ? error: eventcnt;
} }
/* /*
* Perform the transfer of events to user space. * Perform the transfer of events to user space.
*/ */
...@@ -1381,7 +1066,6 @@ static int ep_events_transfer(struct eventpoll *ep, ...@@ -1381,7 +1066,6 @@ static int ep_events_transfer(struct eventpoll *ep,
return eventcnt; return eventcnt;
} }
static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
int maxevents, long timeout) int maxevents, long timeout)
{ {
...@@ -1451,6 +1135,260 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, ...@@ -1451,6 +1135,260 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
return res; 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(&current->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) static int __init eventpoll_init(void)
{ {
mutex_init(&epmutex); mutex_init(&epmutex);
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7