From b5e618181a927210f8be1d3d2249d31904ba358d Mon Sep 17 00:00:00 2001 From: Pavel Emelianov Date: Tue, 8 May 2007 00:30:19 -0700 Subject: [PATCH] Introduce a handy list_first_entry macro 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 Signed-off-by: Kirill Korotaev Cc: Randy Dunlap Cc: Andi Kleen Cc: Zach Brown Cc: Davide Libenzi Cc: John McCutchan Cc: Thomas Gleixner Cc: Ingo Molnar Cc: john stultz Cc: Ram Pai Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/dquot.c | 2 +- fs/eventpoll.c | 6 +++--- fs/inode.c | 2 +- fs/inotify.c | 2 +- fs/namespace.c | 4 ++-- fs/pnode.c | 2 +- include/linux/list.h | 11 +++++++++++ kernel/posix-cpu-timers.c | 14 +++++++------- kernel/timer.c | 4 ++-- 9 files changed, 29 insertions(+), 18 deletions(-) diff --git a/fs/dquot.c b/fs/dquot.c index dcc5a58..3a99584 100644 --- a/fs/dquot.c +++ b/fs/dquot.c @@ -474,7 +474,7 @@ int vfs_quota_sync(struct super_block *sb, int type) spin_lock(&dq_list_lock); dirty = &dqopt->info[cnt].dqi_dirty_list; 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... */ if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) { clear_dquot_dirty(dquot); diff --git a/fs/eventpoll.c b/fs/eventpoll.c index d0b8606..b5c7ca5 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -453,7 +453,7 @@ void eventpoll_release_file(struct file *file) mutex_lock(&epmutex); while (!list_empty(lsthead)) { - epi = list_entry(lsthead->next, struct epitem, fllink); + epi = list_first_entry(lsthead, struct epitem, fllink); ep = epi->ep; list_del_init(&epi->fllink); @@ -1143,7 +1143,7 @@ static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi) if (nwait) { 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); remove_wait_queue(pwq->whead, &pwq->wait); @@ -1359,7 +1359,7 @@ static int ep_send_events(struct eventpoll *ep, struct list_head *txlist, * read. */ 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); /* diff --git a/fs/inode.c b/fs/inode.c index 81508b0..410f235 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -275,7 +275,7 @@ static void dispose_list(struct list_head *head) while (!list_empty(head)) { 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); if (inode->i_data.nrpages) diff --git a/fs/inotify.c b/fs/inotify.c index f5099d8..7457501 100644 --- a/fs/inotify.c +++ b/fs/inotify.c @@ -509,7 +509,7 @@ void inotify_destroy(struct inotify_handle *ih) mutex_unlock(&ih->mutex); 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); mutex_unlock(&ih->mutex); diff --git a/fs/namespace.c b/fs/namespace.c index c5b8810..72bb106 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -499,7 +499,7 @@ void release_mounts(struct list_head *head) { struct vfsmount *mnt; 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); if (mnt->mnt_parent != mnt) { struct dentry *dentry; @@ -1177,7 +1177,7 @@ static void expire_mount_list(struct list_head *graveyard, struct list_head *mou while (!list_empty(graveyard)) { 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); /* don't do anything if the namespace is dead - all the diff --git a/fs/pnode.c b/fs/pnode.c index 56aacea..89940f2 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -59,7 +59,7 @@ static int do_make_slave(struct vfsmount *mnt) } else { struct list_head *p = &mnt->mnt_slave_list; while (!list_empty(p)) { - slave_mnt = list_entry(p->next, + slave_mnt = list_first_entry(p, struct vfsmount, mnt_slave); list_del_init(&slave_mnt->mnt_slave); slave_mnt->mnt_master = NULL; diff --git a/include/linux/list.h b/include/linux/list.h index f9d71ea..9202703 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -426,6 +426,17 @@ static inline void list_splice_init_rcu(struct list_head *list, 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 * @pos: the &struct list_head to use as a loop cursor. * @head: the head for your list. diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index 657f776..1de710e1 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -971,7 +971,7 @@ static void check_thread_timers(struct task_struct *tsk, maxfire = 20; tsk->it_prof_expires = cputime_zero; 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, entry); 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; tsk->it_virt_expires = cputime_zero; 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, entry); 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; tsk->it_sched_expires = 0; 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, entry); if (!--maxfire || tsk->sched_time < t->expires.sched) { @@ -1057,7 +1057,7 @@ static void check_process_timers(struct task_struct *tsk, maxfire = 20; prof_expires = cputime_zero; 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, entry); if (!--maxfire || cputime_lt(ptime, t->expires.cpu)) { @@ -1072,7 +1072,7 @@ static void check_process_timers(struct task_struct *tsk, maxfire = 20; virt_expires = cputime_zero; 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, entry); if (!--maxfire || cputime_lt(utime, t->expires.cpu)) { @@ -1087,7 +1087,7 @@ static void check_process_timers(struct task_struct *tsk, maxfire = 20; sched_expires = 0; 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, entry); 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]; if (list_empty(head) || - cputime_ge(list_entry(head->next, + cputime_ge(list_first_entry(head, struct cpu_timer_list, entry)->expires.cpu, *newval)) { /* diff --git a/kernel/timer.c b/kernel/timer.c index ba41af2..7a64483 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -629,7 +629,7 @@ static inline void __run_timers(tvec_base_t *base) void (*fn)(unsigned long); unsigned long data; - timer = list_entry(head->next,struct timer_list,entry); + timer = list_first_entry(head, struct timer_list,entry); fn = timer->function; 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; 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); timer_set_base(timer, new_base); internal_add_timer(new_base, timer); -- 2.7.4