#include <linux/spinlock.h>
#include <linux/syscalls.h>
#include <linux/rwsem.h>
+#include <linux/rbtree.h>
#include <linux/wait.h>
#include <linux/eventpoll.h>
#include <linux/mount.h>
/* Maximum number of poll wake up nests we are allowing */
#define EP_MAX_POLLWAKE_NESTS 4
-/* Maximum size of the hash in bits ( 2^N ) */
-#define EP_MAX_HASH_BITS 17
-
-/* Minimum size of the hash in bits ( 2^N ) */
-#define EP_MIN_HASH_BITS 9
-
-/* Number of hash entries ( "struct list_head" ) inside a page */
-#define EP_HENTRY_X_PAGE (PAGE_SIZE / sizeof(struct list_head))
-
-/* Maximum size of the hash in pages */
-#define EP_MAX_HPAGES ((1 << EP_MAX_HASH_BITS) / EP_HENTRY_X_PAGE + 1)
-
-/* Number of pages allocated for an "hbits" sized hash table */
-#define EP_HASH_PAGES(hbits) ((int) ((1 << (hbits)) / EP_HENTRY_X_PAGE + \
- ((1 << (hbits)) % EP_HENTRY_X_PAGE ? 1: 0)))
-
/* Macro to allocate a "struct epitem" from the slab cache */
#define EPI_MEM_ALLOC() (struct epitem *) kmem_cache_alloc(epi_cache, SLAB_KERNEL)
/* 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
/* Get the "struct epitem" from an epoll queue wrapper */
#define EP_ITEM_FROM_EPQUEUE(p) (container_of(p, struct ep_pqueue, pt)->epi)
+
+struct epoll_filefd {
+ struct file *file;
+ int fd;
+};
+
/*
* Node that is linked into the "wake_task_list" member of the "struct poll_safewake".
* It is used to keep track on all tasks that are currently inside the wake_up() code
/* List of ready file descriptors */
struct list_head rdllist;
- /* Size of the hash */
- unsigned int hashbits;
-
- /* Pages for the "struct epitem" hash */
- char *hpages[EP_MAX_HPAGES];
+ /* RB-Tree root used to store monitored fd structs */
+ struct rb_root rbr;
};
/* Wait structure used by the poll hooks */
* have an entry of this type linked to the hash.
*/
struct epitem {
- /* List header used to link this structure to the eventpoll hash */
- struct list_head llink;
+ /* RB-Tree node used to link this structure to the eventpoll rb-tree */
+ struct rb_node rbn;
/* List header used to link this structure to the eventpoll ready list */
struct list_head rdllink;
- /* The file descriptor this item refers to */
- int fd;
+ /* The file descriptor information this item refers to */
+ struct epoll_filefd ffd;
/* Number of active wait queue attached to poll operations */
int nwait;
/* The "container" of this item */
struct eventpoll *ep;
- /* The file this item refers to */
- struct file *file;
-
/* The structure that describe the interested events and the source fd */
struct epoll_event event;
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 unsigned int ep_get_hash_bits(unsigned int hintsize);
static int ep_getfd(int *efd, struct inode **einode, struct file **efile);
-static int ep_alloc_pages(char **pages, int numpages);
-static int ep_free_pages(char **pages, int numpages);
-static int ep_file_init(struct file *file, unsigned int hashbits);
-static unsigned int ep_hash_index(struct eventpoll *ep, struct file *file,
- int fd);
-static struct list_head *ep_hash_entry(struct eventpoll *ep,
- unsigned int index);
-static int ep_init(struct eventpoll *ep, unsigned int hashbits);
+static int ep_file_init(struct file *file);
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,
}
-/*
- * Calculate the size of the hash in bits. The returned size will be
- * bounded between EP_MIN_HASH_BITS and EP_MAX_HASH_BITS.
- */
-static unsigned int ep_get_hash_bits(unsigned int hintsize)
-{
- unsigned int i, val;
-
- for (i = 0, val = 1; val < hintsize && i < EP_MAX_HASH_BITS; i++, val <<= 1);
- return i < EP_MIN_HASH_BITS ? EP_MIN_HASH_BITS: i;
-}
-
-
/* Used to initialize the epoll bits inside the "struct file" */
void eventpoll_init_file(struct file *file)
{
asmlinkage long sys_epoll_create(int size)
{
int error, fd;
- unsigned int hashbits;
struct inode *inode;
struct file *file;
if (size <= 0)
goto eexit_1;
- /* Correctly size the hash */
- hashbits = ep_get_hash_bits((unsigned int) size);
-
/*
* Creates all the items needed to setup an eventpoll file. That is,
* a file structure, and inode and a free file descriptor.
goto eexit_1;
/* Setup the file internal data structure ( "struct eventpoll" ) */
- error = ep_file_init(file, hashbits);
+ error = ep_file_init(file);
if (error)
goto eexit_2;
dentry->d_op = &eventpollfs_dentry_operations;
d_add(dentry, inode);
file->f_vfsmnt = mntget(eventpoll_mnt);
- file->f_dentry = dget(dentry);
+ file->f_dentry = dentry;
file->f_mapping = inode->i_mapping;
file->f_pos = 0;
}
-static int ep_alloc_pages(char **pages, int numpages)
+static int ep_file_init(struct file *file)
{
- int i;
-
- for (i = 0; i < numpages; i++) {
- pages[i] = (char *) __get_free_pages(GFP_KERNEL, 0);
- if (!pages[i]) {
- for (--i; i >= 0; i--) {
- ClearPageReserved(virt_to_page(pages[i]));
- free_pages((unsigned long) pages[i], 0);
- }
- return -ENOMEM;
- }
- SetPageReserved(virt_to_page(pages[i]));
- }
- return 0;
-}
-
-
-static int ep_free_pages(char **pages, int numpages)
-{
- int i;
-
- for (i = 0; i < numpages; i++) {
- ClearPageReserved(virt_to_page(pages[i]));
- free_pages((unsigned long) pages[i], 0);
- }
- return 0;
-}
-
-
-static int ep_file_init(struct file *file, unsigned int hashbits)
-{
- int error;
struct eventpoll *ep;
if (!(ep = kmalloc(sizeof(struct eventpoll), GFP_KERNEL)))
return -ENOMEM;
memset(ep, 0, sizeof(*ep));
-
- error = ep_init(ep, hashbits);
- if (error) {
- kfree(ep);
- return error;
- }
-
- file->private_data = ep;
-
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_file_init() ep=%p\n",
- current, ep));
- return 0;
-}
-
-
-/*
- * Calculate the index of the hash relative to "file".
- */
-static unsigned int ep_hash_index(struct eventpoll *ep, struct file *file, int fd)
-{
- unsigned long ptr = (unsigned long) file ^ (fd << ep->hashbits);
-
- return (unsigned int) hash_ptr((void *) ptr, ep->hashbits);
-}
-
-
-/*
- * Returns the hash entry ( struct list_head * ) of the passed index.
- */
-static struct list_head *ep_hash_entry(struct eventpoll *ep, unsigned int index)
-{
-
- return (struct list_head *) (ep->hpages[index / EP_HENTRY_X_PAGE] +
- (index % EP_HENTRY_X_PAGE) * sizeof(struct list_head));
-}
-
-
-static int ep_init(struct eventpoll *ep, unsigned int hashbits)
-{
- int error;
- unsigned int i, hsize;
-
rwlock_init(&ep->lock);
init_rwsem(&ep->sem);
init_waitqueue_head(&ep->wq);
init_waitqueue_head(&ep->poll_wait);
INIT_LIST_HEAD(&ep->rdllist);
+ ep->rbr = RB_ROOT;
- /* Hash allocation and setup */
- ep->hashbits = hashbits;
- error = ep_alloc_pages(ep->hpages, EP_HASH_PAGES(ep->hashbits));
- if (error)
- goto eexit_1;
-
- /* Initialize hash buckets */
- for (i = 0, hsize = 1 << hashbits; i < hsize; i++)
- INIT_LIST_HEAD(ep_hash_entry(ep, i));
+ file->private_data = ep;
+ DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_file_init() ep=%p\n",
+ current, ep));
return 0;
-eexit_1:
- return error;
}
static void ep_free(struct eventpoll *ep)
{
- unsigned int i, hsize;
- struct list_head *lsthead, *lnk;
+ struct rb_node *rbp;
struct epitem *epi;
/* We need to release all tasks waiting for these file */
down(&epsem);
/*
- * Walks through the whole hash by unregistering poll callbacks.
+ * Walks through the whole tree by unregistering poll callbacks.
*/
- for (i = 0, hsize = 1 << ep->hashbits; i < hsize; i++) {
- lsthead = ep_hash_entry(ep, i);
+ for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
+ epi = rb_entry(rbp, struct epitem, rbn);
- list_for_each(lnk, lsthead) {
- epi = list_entry(lnk, struct epitem, llink);
-
- ep_unregister_pollwait(ep, epi);
- }
+ ep_unregister_pollwait(ep, epi);
}
/*
* 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".
*/
- for (i = 0, hsize = 1 << ep->hashbits; i < hsize; i++) {
- lsthead = ep_hash_entry(ep, i);
-
- while (!list_empty(lsthead)) {
- epi = list_entry(lsthead->next, struct epitem, llink);
-
- ep_remove(ep, epi);
- }
+ while ((rbp = rb_first(&ep->rbr)) != 0) {
+ epi = rb_entry(rbp, struct epitem, rbn);
+ ep_remove(ep, epi);
}
up(&epsem);
-
- /* Free hash pages */
- ep_free_pages(ep->hpages, EP_HASH_PAGES(ep->hashbits));
}
*/
static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd)
{
+ int kcmp;
unsigned long flags;
- struct list_head *lsthead, *lnk;
- struct epitem *epi = NULL;
+ struct rb_node *rbp;
+ struct epitem *epi, *epir = NULL;
+ struct epoll_filefd ffd;
+ EP_SET_FFD(&ffd, file, fd);
read_lock_irqsave(&ep->lock, flags);
-
- lsthead = ep_hash_entry(ep, ep_hash_index(ep, file, fd));
- list_for_each(lnk, lsthead) {
- epi = list_entry(lnk, struct epitem, llink);
-
- if (epi->file == file && epi->fd == fd) {
+ for (rbp = ep->rbr.rb_node; rbp; ) {
+ epi = rb_entry(rbp, struct epitem, rbn);
+ kcmp = EP_CMP_FFD(&ffd, &epi->ffd);
+ if (kcmp > 0)
+ rbp = rbp->rb_right;
+ else if (kcmp < 0)
+ rbp = rbp->rb_left;
+ else {
ep_use_epitem(epi);
+ epir = epi;
break;
}
- epi = NULL;
}
-
read_unlock_irqrestore(&ep->lock, flags);
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_find(%p) -> %p\n",
- current, file, epi));
+ current, file, epir));
- return epi;
+ return epir;
}
}
+static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
+{
+ int kcmp;
+ struct rb_node **p = &ep->rbr.rb_node, *parent = NULL;
+ struct epitem *epic;
+
+ while (*p) {
+ parent = *p;
+ epic = rb_entry(parent, struct epitem, rbn);
+ kcmp = EP_CMP_FFD(&epi->ffd, &epic->ffd);
+ if (kcmp > 0)
+ p = &parent->rb_right;
+ else
+ p = &parent->rb_left;
+ }
+ rb_link_node(&epi->rbn, parent, p);
+ rb_insert_color(&epi->rbn, &ep->rbr);
+}
+
+
static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
struct file *tfile, int fd)
{
goto eexit_1;
/* Item initialization follow here ... */
- INIT_LIST_HEAD(&epi->llink);
+ 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;
- epi->file = tfile;
- epi->fd = fd;
+ EP_SET_FFD(&epi->ffd, tfile, fd);
epi->event = *event;
atomic_set(&epi->usecnt, 1);
epi->nwait = 0;
/* We have to drop the new item inside our item list to keep track of it */
write_lock_irqsave(&ep->lock, flags);
- /* Add the current item to the hash table */
- list_add(&epi->llink, ep_hash_entry(ep, ep_hash_index(ep, tfile, fd)));
+ /* Add the current item to the rb-tree */
+ 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)) {
* Get current event bits. We can safely use the file* here because
* its usage count has been increased by the caller of this function.
*/
- revents = epi->file->f_op->poll(epi->file, NULL);
+ revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL);
write_lock_irqsave(&ep->lock, flags);
* If the item is not linked to the hash it means that it's on its
* way toward the removal. Do nothing in this case.
*/
- if (EP_IS_LINKED(&epi->llink)) {
+ 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
* The check protect us from doing a double unlink ( crash ).
*/
error = -ENOENT;
- if (!EP_IS_LINKED(&epi->llink))
+ if (!EP_RB_LINKED(&epi->rbn))
goto eexit_1;
/*
epi->event.events = 0;
/*
- * At this point is safe to do the job, unlink the item from our list.
+ * 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_LIST_DEL(&epi->llink);
+ EP_RB_ERASE(&epi->rbn, &ep->rbr);
/*
* If the item we are going to remove is inside the ready file descriptors
{
int error;
unsigned long flags;
- struct file *file = epi->file;
+ struct file *file = epi->ffd.file;
/*
* Removes poll wait queue hooks. We _have_ to do this without holding
* because we are holding the "sem" in read and this will
* guarantee that both the file and the item will not vanish.
*/
- revents = epi->file->f_op->poll(epi->file, NULL);
+ revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL);
/*
* Set the return event set for the current file descriptor.
* item is set to have an Edge Triggered behaviour, we don't have
* to push it back either.
*/
- if (EP_IS_LINKED(&epi->llink) && !(epi->event.events & EPOLLET) &&
+ 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++;
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