From c59cd3d840b1b0a8f996cbbd9132128dcaabbeb9 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 8 Aug 2013 20:11:26 -0400 Subject: [PATCH] cgroup: make cgroup_task_iter remember the cgroup being iterated Currently all cgroup_task_iter functions require @cgrp to be passed in, which is superflous and increases chance of usage error. Make cgroup_task_iter remember the cgroup being iterated and drop @cgrp argument from next and end functions. This patch doesn't introduce any behavior differences. Signed-off-by: Tejun Heo Acked-by: Li Zefan Acked-by: Michal Hocko Cc: Matt Helsley Cc: Johannes Weiner Cc: Balbir Singh --- include/linux/cgroup.h | 6 +++--- kernel/cgroup.c | 32 +++++++++++++++----------------- kernel/cgroup_freezer.c | 12 ++++++------ mm/memcontrol.c | 6 +++--- 4 files changed, 27 insertions(+), 29 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index ea439794bd9b..0287fccd0f54 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -891,14 +891,14 @@ css_next_descendant_post(struct cgroup_subsys_state *pos, /* A cgroup_task_iter should be treated as an opaque object */ struct cgroup_task_iter { + struct cgroup *origin_cgrp; struct list_head *cset_link; struct list_head *task; }; void cgroup_task_iter_start(struct cgroup *cgrp, struct cgroup_task_iter *it); -struct task_struct *cgroup_task_iter_next(struct cgroup *cgrp, - struct cgroup_task_iter *it); -void cgroup_task_iter_end(struct cgroup *cgrp, struct cgroup_task_iter *it); +struct task_struct *cgroup_task_iter_next(struct cgroup_task_iter *it); +void cgroup_task_iter_end(struct cgroup_task_iter *it); int cgroup_scan_tasks(struct cgroup_scanner *scan); int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from); diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 15c93f9c9e57..abc62ea1303c 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3205,13 +3205,11 @@ EXPORT_SYMBOL_GPL(css_next_descendant_post); /** * cgroup_advance_task_iter - advance a task itererator to the next css_set - * @cgrp: the cgroup to walk tasks of * @it: the iterator to advance * * Advance @it to the next css_set to walk. */ -static void cgroup_advance_task_iter(struct cgroup *cgrp, - struct cgroup_task_iter *it) +static void cgroup_advance_task_iter(struct cgroup_task_iter *it) { struct list_head *l = it->cset_link; struct cgrp_cset_link *link; @@ -3220,7 +3218,7 @@ static void cgroup_advance_task_iter(struct cgroup *cgrp, /* Advance to the next non-empty css_set */ do { l = l->next; - if (l == &cgrp->cset_links) { + if (l == &it->origin_cgrp->cset_links) { it->cset_link = NULL; return; } @@ -3257,21 +3255,22 @@ void cgroup_task_iter_start(struct cgroup *cgrp, struct cgroup_task_iter *it) cgroup_enable_task_cg_lists(); read_lock(&css_set_lock); + + it->origin_cgrp = cgrp; it->cset_link = &cgrp->cset_links; - cgroup_advance_task_iter(cgrp, it); + + cgroup_advance_task_iter(it); } /** * cgroup_task_iter_next - return the next task for the iterator - * @cgrp: the cgroup to walk tasks of * @it: the task iterator being iterated * * The "next" function for task iteration. @it should have been * initialized via cgroup_task_iter_start(). Returns NULL when the * iteration reaches the end. */ -struct task_struct *cgroup_task_iter_next(struct cgroup *cgrp, - struct cgroup_task_iter *it) +struct task_struct *cgroup_task_iter_next(struct cgroup_task_iter *it) { struct task_struct *res; struct list_head *l = it->task; @@ -3289,7 +3288,7 @@ struct task_struct *cgroup_task_iter_next(struct cgroup *cgrp, * We reached the end of this task list - move on to the * next cgrp_cset_link. */ - cgroup_advance_task_iter(cgrp, it); + cgroup_advance_task_iter(it); } else { it->task = l; } @@ -3298,12 +3297,11 @@ struct task_struct *cgroup_task_iter_next(struct cgroup *cgrp, /** * cgroup_task_iter_end - finish task iteration - * @cgrp: the cgroup to walk tasks of * @it: the task iterator to finish * * Finish task iteration started by cgroup_task_iter_start(). */ -void cgroup_task_iter_end(struct cgroup *cgrp, struct cgroup_task_iter *it) +void cgroup_task_iter_end(struct cgroup_task_iter *it) __releases(css_set_lock) { read_unlock(&css_set_lock); @@ -3409,7 +3407,7 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan) */ heap->size = 0; cgroup_task_iter_start(scan->cgrp, &it); - while ((p = cgroup_task_iter_next(scan->cgrp, &it))) { + while ((p = cgroup_task_iter_next(&it))) { /* * Only affect tasks that qualify per the caller's callback, * if he provided one @@ -3442,7 +3440,7 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan) * the heap and wasn't inserted */ } - cgroup_task_iter_end(scan->cgrp, &it); + cgroup_task_iter_end(&it); if (heap->size) { for (i = 0; i < heap->size; i++) { @@ -3664,7 +3662,7 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, return -ENOMEM; /* now, populate the array */ cgroup_task_iter_start(cgrp, &it); - while ((tsk = cgroup_task_iter_next(cgrp, &it))) { + while ((tsk = cgroup_task_iter_next(&it))) { if (unlikely(n == length)) break; /* get tgid or pid for procs or tasks file respectively */ @@ -3675,7 +3673,7 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, if (pid > 0) /* make sure to only use valid results */ array[n++] = pid; } - cgroup_task_iter_end(cgrp, &it); + cgroup_task_iter_end(&it); length = n; /* now sort & (if procs) strip out duplicates */ sort(array, length, sizeof(pid_t), cmppid, NULL); @@ -3724,7 +3722,7 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) cgrp = dentry->d_fsdata; cgroup_task_iter_start(cgrp, &it); - while ((tsk = cgroup_task_iter_next(cgrp, &it))) { + while ((tsk = cgroup_task_iter_next(&it))) { switch (tsk->state) { case TASK_RUNNING: stats->nr_running++; @@ -3744,7 +3742,7 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) break; } } - cgroup_task_iter_end(cgrp, &it); + cgroup_task_iter_end(&it); err: return ret; diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c index c9177f8fc661..e0ab9bfd679a 100644 --- a/kernel/cgroup_freezer.c +++ b/kernel/cgroup_freezer.c @@ -281,7 +281,7 @@ static void update_if_frozen(struct cgroup_subsys_state *css) /* are all tasks frozen? */ cgroup_task_iter_start(css->cgroup, &it); - while ((task = cgroup_task_iter_next(css->cgroup, &it))) { + while ((task = cgroup_task_iter_next(&it))) { if (freezing(task)) { /* * freezer_should_skip() indicates that the task @@ -296,7 +296,7 @@ static void update_if_frozen(struct cgroup_subsys_state *css) freezer->state |= CGROUP_FROZEN; out_iter_end: - cgroup_task_iter_end(css->cgroup, &it); + cgroup_task_iter_end(&it); out_unlock: spin_unlock_irq(&freezer->lock); } @@ -327,9 +327,9 @@ static void freeze_cgroup(struct freezer *freezer) struct task_struct *task; cgroup_task_iter_start(cgroup, &it); - while ((task = cgroup_task_iter_next(cgroup, &it))) + while ((task = cgroup_task_iter_next(&it))) freeze_task(task); - cgroup_task_iter_end(cgroup, &it); + cgroup_task_iter_end(&it); } static void unfreeze_cgroup(struct freezer *freezer) @@ -339,9 +339,9 @@ static void unfreeze_cgroup(struct freezer *freezer) struct task_struct *task; cgroup_task_iter_start(cgroup, &it); - while ((task = cgroup_task_iter_next(cgroup, &it))) + while ((task = cgroup_task_iter_next(&it))) __thaw_task(task); - cgroup_task_iter_end(cgroup, &it); + cgroup_task_iter_end(&it); } /** diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 00b055dd1d3d..5a5f4dc649f0 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1804,7 +1804,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, struct task_struct *task; cgroup_task_iter_start(cgroup, &it); - while ((task = cgroup_task_iter_next(cgroup, &it))) { + while ((task = cgroup_task_iter_next(&it))) { switch (oom_scan_process_thread(task, totalpages, NULL, false)) { case OOM_SCAN_SELECT: @@ -1817,7 +1817,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, case OOM_SCAN_CONTINUE: continue; case OOM_SCAN_ABORT: - cgroup_task_iter_end(cgroup, &it); + cgroup_task_iter_end(&it); mem_cgroup_iter_break(memcg, iter); if (chosen) put_task_struct(chosen); @@ -1834,7 +1834,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, get_task_struct(chosen); } } - cgroup_task_iter_end(cgroup, &it); + cgroup_task_iter_end(&it); } if (!chosen) -- 2.20.1