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[PATCH] Remove eventpoll macro obfuscation
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This patch gets rid of some macro obfuscation from fs/eventpoll.c by
removing slab allocator wrappers and converting macros to static inline
functions.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Pekka Enberg authored and Linus Torvalds committed Jun 23, 2005
1 parent 46c271b commit b030a4d
Showing 1 changed file with 110 additions and 85 deletions.
195 changes: 110 additions & 85 deletions fs/eventpoll.c
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Original file line number Diff line number Diff line change
Expand Up @@ -101,57 +101,6 @@
/* 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)

/* 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)


struct epoll_filefd {
struct file *file;
int fd;
Expand Down Expand Up @@ -357,6 +306,82 @@ static struct dentry_operations eventpollfs_dentry_operations = {



/* 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)
{
n->rb_parent = 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);
n->rb_parent = 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 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)".
*/
static inline void ep_list_del(struct list_head *p)
{
list_del(p);
INIT_LIST_HEAD(p);
}

/* 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_hash_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)
{
Expand Down Expand Up @@ -456,7 +481,7 @@ void eventpoll_release_file(struct file *file)
epi = list_entry(lsthead->next, struct epitem, fllink);

ep = epi->ep;
EP_LIST_DEL(&epi->fllink);
ep_list_del(&epi->fllink);
down_write(&ep->sem);
ep_remove(ep, epi);
up_write(&ep->sem);
Expand Down Expand Up @@ -534,7 +559,7 @@ sys_epoll_ctl(int epfd, int op, int fd, struct epoll_event __user *event)
current, epfd, op, fd, event));

error = -EFAULT;
if (EP_OP_HASH_EVENT(op) &&
if (ep_op_hash_event(op) &&
copy_from_user(&epds, event, sizeof(struct epoll_event)))
goto eexit_1;

Expand All @@ -560,7 +585,7 @@ sys_epoll_ctl(int epfd, int op, int fd, struct epoll_event __user *event)
* 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;

/*
Expand Down Expand Up @@ -656,7 +681,7 @@ asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events,
* the user passed to us _is_ an eventpoll file.
*/
error = -EINVAL;
if (!IS_FILE_EPOLL(file))
if (!is_file_epoll(file))
goto eexit_2;

/*
Expand Down Expand Up @@ -831,11 +856,11 @@ static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd)
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)
Expand Down Expand Up @@ -875,7 +900,7 @@ static void ep_release_epitem(struct epitem *epi)
{

if (atomic_dec_and_test(&epi->usecnt))
EPI_MEM_FREE(epi);
kmem_cache_free(epi_cache, epi);
}


Expand All @@ -886,10 +911,10 @@ 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)
{
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, SLAB_KERNEL))) {
init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
pwq->whead = whead;
pwq->base = epi;
Expand All @@ -912,7 +937,7 @@ static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *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
Expand All @@ -932,17 +957,17 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
struct ep_pqueue epq;

error = -ENOMEM;
if (!(epi = EPI_MEM_ALLOC()))
if (!(epi = kmem_cache_alloc(epi_cache, SLAB_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;
Expand Down Expand Up @@ -978,7 +1003,7 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
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 */
Expand Down Expand Up @@ -1007,11 +1032,11 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
* 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))
ep_list_del(&epi->rdllink);
write_unlock_irqrestore(&ep->lock, flags);

EPI_MEM_FREE(epi);
kmem_cache_free(epi_cache, epi);
eexit_1:
return error;
}
Expand Down Expand Up @@ -1050,14 +1075,14 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_even
* 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_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 */
Expand Down Expand Up @@ -1097,9 +1122,9 @@ static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi)
while (!list_empty(lsthead)) {
pwq = list_entry(lsthead->next, struct eppoll_entry, llink);

EP_LIST_DEL(&pwq->llink);
ep_list_del(&pwq->llink);
remove_wait_queue(pwq->whead, &pwq->wait);
PWQ_MEM_FREE(pwq);
kmem_cache_free(pwq_cache, pwq);
}
}
}
Expand All @@ -1118,7 +1143,7 @@ static int ep_unlink(struct eventpoll *ep, struct epitem *epi)
* 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;

/*
Expand All @@ -1133,14 +1158,14 @@ static int ep_unlink(struct eventpoll *ep, struct epitem *epi)
* 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))
ep_list_del(&epi->rdllink);

error = 0;
eexit_1:
Expand Down Expand Up @@ -1174,8 +1199,8 @@ 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))
ep_list_del(&epi->fllink);
spin_unlock(&file->f_ep_lock);

/* We need to acquire the write IRQ lock before calling ep_unlink() */
Expand Down Expand Up @@ -1210,7 +1235,7 @@ static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *k
{
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",
Expand All @@ -1228,7 +1253,7 @@ static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *k
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);
Expand Down Expand Up @@ -1307,7 +1332,7 @@ static int ep_collect_ready_items(struct eventpoll *ep, struct list_head *txlist
lnk = lnk->next;

/* If this file is already in the ready list we exit soon */
if (!EP_IS_LINKED(&epi->txlink)) {
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
Expand All @@ -1322,7 +1347,7 @@ static int ep_collect_ready_items(struct eventpoll *ep, struct list_head *txlist
/*
* Unlink the item from the ready list.
*/
EP_LIST_DEL(&epi->rdllink);
ep_list_del(&epi->rdllink);
}
}

Expand Down Expand Up @@ -1401,7 +1426,7 @@ static void ep_reinject_items(struct eventpoll *ep, struct list_head *txlist)
epi = list_entry(txlist->next, struct epitem, txlink);

/* Unlink the current item from the transfer list */
EP_LIST_DEL(&epi->txlink);
ep_list_del(&epi->txlink);

/*
* If the item is no more linked to the interest set, we don't
Expand All @@ -1410,8 +1435,8 @@ static void ep_reinject_items(struct eventpoll *ep, struct list_head *txlist)
* item is set to have an Edge Triggered behaviour, we don't have
* to push it back either.
*/
if (EP_RB_LINKED(&epi->rbn) && !(epi->event.events & EPOLLET) &&
(epi->revents & epi->event.events) && !EP_IS_LINKED(&epi->rdllink)) {
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++;
}
Expand Down

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