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Introduce a handy list_first_entry macro

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There are many places in the kernel where the construction like

   foo = list_entry(head->next, struct foo_struct, list);

are used.
The code might look more descriptive and neat if using the macro

   list_first_entry(head, type, member) \
             list_entry((head)->next, type, member)

Here is the macro itself and the examples of its usage in the generic code.
 If it will turn out to be useful, I can prepare the set of patches to
inject in into arch-specific code, drivers, networking, etc.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Signed-off-by: Kirill Korotaev <dev@openvz.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Zach Brown <zach.brown@oracle.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Pavel Emelianov 2007-05-08 00:30:19 -07:00 committed by Linus Torvalds
parent db9c02fa8b
commit b5e618181a
9 changed files with 29 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/dquot.c
View File

@ -474,7 +474,7 @@ int vfs_quota_sync(struct super_block *sb, int type)
spin_lock(&dq_list_lock); spin_lock(&dq_list_lock);
dirty = &dqopt->info[cnt].dqi_dirty_list; dirty = &dqopt->info[cnt].dqi_dirty_list;
while (!list_empty(dirty)) { while (!list_empty(dirty)) {
dquot = list_entry(dirty->next, struct dquot, dq_dirty); dquot = list_first_entry(dirty, struct dquot, dq_dirty);
/* Dirty and inactive can be only bad dquot... */ /* Dirty and inactive can be only bad dquot... */
if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) { if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
clear_dquot_dirty(dquot); clear_dquot_dirty(dquot);

6
fs/eventpoll.c
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@ -453,7 +453,7 @@ void eventpoll_release_file(struct file *file)
mutex_lock(&epmutex); mutex_lock(&epmutex);
while (!list_empty(lsthead)) { while (!list_empty(lsthead)) {
epi = list_entry(lsthead->next, struct epitem, fllink); epi = list_first_entry(lsthead, struct epitem, fllink);
ep = epi->ep; ep = epi->ep;
list_del_init(&epi->fllink); list_del_init(&epi->fllink);
@ -1143,7 +1143,7 @@ static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi)
if (nwait) { if (nwait) {
while (!list_empty(lsthead)) { while (!list_empty(lsthead)) {
pwq = list_entry(lsthead->next, struct eppoll_entry, llink); pwq = list_first_entry(lsthead, struct eppoll_entry, llink);
list_del_init(&pwq->llink); list_del_init(&pwq->llink);
remove_wait_queue(pwq->whead, &pwq->wait); remove_wait_queue(pwq->whead, &pwq->wait);
@ -1359,7 +1359,7 @@ static int ep_send_events(struct eventpoll *ep, struct list_head *txlist,
* read. * read.
*/ */
for (eventcnt = 0; !list_empty(txlist) && eventcnt < maxevents;) { for (eventcnt = 0; !list_empty(txlist) && eventcnt < maxevents;) {
epi = list_entry(txlist->next, struct epitem, rdllink); epi = list_first_entry(txlist, struct epitem, rdllink);
prefetch(epi->rdllink.next); prefetch(epi->rdllink.next);
/* /*

2
fs/inode.c
View File

@ -275,7 +275,7 @@ static void dispose_list(struct list_head *head)
while (!list_empty(head)) { while (!list_empty(head)) {
struct inode *inode; struct inode *inode;
inode = list_entry(head->next, struct inode, i_list); inode = list_first_entry(head, struct inode, i_list);
list_del(&inode->i_list); list_del(&inode->i_list);
if (inode->i_data.nrpages) if (inode->i_data.nrpages)

2
fs/inotify.c
View File

@ -509,7 +509,7 @@ void inotify_destroy(struct inotify_handle *ih)
mutex_unlock(&ih->mutex); mutex_unlock(&ih->mutex);
break; break;
} }
watch = list_entry(watches->next, struct inotify_watch, h_list); watch = list_first_entry(watches, struct inotify_watch, h_list);
get_inotify_watch(watch); get_inotify_watch(watch);
mutex_unlock(&ih->mutex); mutex_unlock(&ih->mutex);

4
fs/namespace.c
View File

@ -499,7 +499,7 @@ void release_mounts(struct list_head *head)
{ {
struct vfsmount *mnt; struct vfsmount *mnt;
while (!list_empty(head)) { while (!list_empty(head)) {
mnt = list_entry(head->next, struct vfsmount, mnt_hash); mnt = list_first_entry(head, struct vfsmount, mnt_hash);
list_del_init(&mnt->mnt_hash); list_del_init(&mnt->mnt_hash);
if (mnt->mnt_parent != mnt) { if (mnt->mnt_parent != mnt) {
struct dentry *dentry; struct dentry *dentry;
@ -1177,7 +1177,7 @@ static void expire_mount_list(struct list_head *graveyard, struct list_head *mou
while (!list_empty(graveyard)) { while (!list_empty(graveyard)) {
LIST_HEAD(umounts); LIST_HEAD(umounts);
mnt = list_entry(graveyard->next, struct vfsmount, mnt_expire); mnt = list_first_entry(graveyard, struct vfsmount, mnt_expire);
list_del_init(&mnt->mnt_expire); list_del_init(&mnt->mnt_expire);
/* don't do anything if the namespace is dead - all the /* don't do anything if the namespace is dead - all the

2
fs/pnode.c
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@ -59,7 +59,7 @@ static int do_make_slave(struct vfsmount *mnt)
} else { } else {
struct list_head *p = &mnt->mnt_slave_list; struct list_head *p = &mnt->mnt_slave_list;
while (!list_empty(p)) { while (!list_empty(p)) {
slave_mnt = list_entry(p->next, slave_mnt = list_first_entry(p,
struct vfsmount, mnt_slave); struct vfsmount, mnt_slave);
list_del_init(&slave_mnt->mnt_slave); list_del_init(&slave_mnt->mnt_slave);
slave_mnt->mnt_master = NULL; slave_mnt->mnt_master = NULL;

11
include/linux/list.h
View File

@ -425,6 +425,17 @@ static inline void list_splice_init_rcu(struct list_head *list,
#define list_entry(ptr, type, member) \ #define list_entry(ptr, type, member) \
container_of(ptr, type, member) container_of(ptr, type, member)
/**
* list_first_entry - get the first element from a list
* @ptr: the list head to take the element from.
* @type: the type of the struct this is embedded in.
* @member: the name of the list_struct within the struct.
*
* Note, that list is expected to be not empty.
*/
#define list_first_entry(ptr, type, member) \
list_entry((ptr)->next, type, member)
/** /**
* list_for_each - iterate over a list * list_for_each - iterate over a list
* @pos: the &struct list_head to use as a loop cursor. * @pos: the &struct list_head to use as a loop cursor.

14
kernel/posix-cpu-timers.c
View File

@ -971,7 +971,7 @@ static void check_thread_timers(struct task_struct *tsk,
maxfire = 20; maxfire = 20;
tsk->it_prof_expires = cputime_zero; tsk->it_prof_expires = cputime_zero;
while (!list_empty(timers)) { while (!list_empty(timers)) {
struct cpu_timer_list *t = list_entry(timers->next, struct cpu_timer_list *t = list_first_entry(timers,
struct cpu_timer_list, struct cpu_timer_list,
entry); entry);
if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) { if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
@ -986,7 +986,7 @@ static void check_thread_timers(struct task_struct *tsk,
maxfire = 20; maxfire = 20;
tsk->it_virt_expires = cputime_zero; tsk->it_virt_expires = cputime_zero;
while (!list_empty(timers)) { while (!list_empty(timers)) {
struct cpu_timer_list *t = list_entry(timers->next, struct cpu_timer_list *t = list_first_entry(timers,
struct cpu_timer_list, struct cpu_timer_list,
entry); entry);
if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) { if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
@ -1001,7 +1001,7 @@ static void check_thread_timers(struct task_struct *tsk,
maxfire = 20; maxfire = 20;
tsk->it_sched_expires = 0; tsk->it_sched_expires = 0;
while (!list_empty(timers)) { while (!list_empty(timers)) {
struct cpu_timer_list *t = list_entry(timers->next, struct cpu_timer_list *t = list_first_entry(timers,
struct cpu_timer_list, struct cpu_timer_list,
entry); entry);
if (!--maxfire || tsk->sched_time < t->expires.sched) { if (!--maxfire || tsk->sched_time < t->expires.sched) {
@ -1057,7 +1057,7 @@ static void check_process_timers(struct task_struct *tsk,
maxfire = 20; maxfire = 20;
prof_expires = cputime_zero; prof_expires = cputime_zero;
while (!list_empty(timers)) { while (!list_empty(timers)) {
struct cpu_timer_list *t = list_entry(timers->next, struct cpu_timer_list *t = list_first_entry(timers,
struct cpu_timer_list, struct cpu_timer_list,
entry); entry);
if (!--maxfire || cputime_lt(ptime, t->expires.cpu)) { if (!--maxfire || cputime_lt(ptime, t->expires.cpu)) {
@ -1072,7 +1072,7 @@ static void check_process_timers(struct task_struct *tsk,
maxfire = 20; maxfire = 20;
virt_expires = cputime_zero; virt_expires = cputime_zero;
while (!list_empty(timers)) { while (!list_empty(timers)) {
struct cpu_timer_list *t = list_entry(timers->next, struct cpu_timer_list *t = list_first_entry(timers,
struct cpu_timer_list, struct cpu_timer_list,
entry); entry);
if (!--maxfire || cputime_lt(utime, t->expires.cpu)) { if (!--maxfire || cputime_lt(utime, t->expires.cpu)) {
@ -1087,7 +1087,7 @@ static void check_process_timers(struct task_struct *tsk,
maxfire = 20; maxfire = 20;
sched_expires = 0; sched_expires = 0;
while (!list_empty(timers)) { while (!list_empty(timers)) {
struct cpu_timer_list *t = list_entry(timers->next, struct cpu_timer_list *t = list_first_entry(timers,
struct cpu_timer_list, struct cpu_timer_list,
entry); entry);
if (!--maxfire || sched_time < t->expires.sched) { if (!--maxfire || sched_time < t->expires.sched) {
@ -1400,7 +1400,7 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
*/ */
head = &tsk->signal->cpu_timers[clock_idx]; head = &tsk->signal->cpu_timers[clock_idx];
if (list_empty(head) || if (list_empty(head) ||
cputime_ge(list_entry(head->next, cputime_ge(list_first_entry(head,
struct cpu_timer_list, entry)->expires.cpu, struct cpu_timer_list, entry)->expires.cpu,
*newval)) { *newval)) {
/* /*

4
kernel/timer.c
View File

@ -629,7 +629,7 @@ static inline void __run_timers(tvec_base_t *base)
void (*fn)(unsigned long); void (*fn)(unsigned long);
unsigned long data; unsigned long data;
timer = list_entry(head->next,struct timer_list,entry); timer = list_first_entry(head, struct timer_list,entry);
fn = timer->function; fn = timer->function;
data = timer->data; data = timer->data;
@ -1248,7 +1248,7 @@ static void migrate_timer_list(tvec_base_t *new_base, struct list_head *head)
struct timer_list *timer; struct timer_list *timer;
while (!list_empty(head)) { while (!list_empty(head)) {
timer = list_entry(head->next, struct timer_list, entry); timer = list_first_entry(head, struct timer_list, entry);
detach_timer(timer, 0); detach_timer(timer, 0);
timer_set_base(timer, new_base); timer_set_base(timer, new_base);
internal_add_timer(new_base, timer); internal_add_timer(new_base, timer);