From 3ed80a62bf959d34ebd4d553b026fbe7e6fbcc54 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sat, 8 Feb 2014 10:36:58 -0500 Subject: cgroup: drop module support With module supported dropped from net_prio, no controller is using cgroup module support. None of actual resource controllers can be built as a module and we aren't gonna add new controllers which don't control resources. This patch drops module support from cgroup. * cgroup_[un]load_subsys() and cgroup_subsys->module removed. * As there's no point in distinguishing IS_BUILTIN() and IS_MODULE(), cgroup_subsys.h now uses IS_ENABLED() directly. * enum cgroup_subsys_id now exactly matches the list of enabled controllers as ordered in cgroup_subsys.h. * cgroup_subsys[] is now a contiguously occupied array. Size specification is no longer necessary and dropped. * for_each_builtin_subsys() is removed and for_each_subsys() is updated to not require any locking. * module ref handling is removed from rebind_subsystems(). * Module related comments dropped. v2: Rebased on top of fe1217c4f3f7 ("net: net_cls: move cgroupfs classid handling into core"). v3: Added {} around the if (need_forkexit_callback) block in cgroup_post_fork() for readability as suggested by Li. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- block/blk-cgroup.c | 1 - 1 file changed, 1 deletion(-) (limited to 'block') diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 4e491d9b5292..660d419918a7 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -914,7 +914,6 @@ struct cgroup_subsys blkio_subsys = { .can_attach = blkcg_can_attach, .subsys_id = blkio_subsys_id, .base_cftypes = blkcg_files, - .module = THIS_MODULE, }; EXPORT_SYMBOL_GPL(blkio_subsys); -- cgit v1.2.3 From 073219e995b4a3f8cf1ce8228b7ef440b6994ac0 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sat, 8 Feb 2014 10:36:58 -0500 Subject: cgroup: clean up cgroup_subsys names and initialization cgroup_subsys is a bit messier than it needs to be. * The name of a subsys can be different from its internal identifier defined in cgroup_subsys.h. Most subsystems use the matching name but three - cpu, memory and perf_event - use different ones. * cgroup_subsys_id enums are postfixed with _subsys_id and each cgroup_subsys is postfixed with _subsys. cgroup.h is widely included throughout various subsystems, it doesn't and shouldn't have claim on such generic names which don't have any qualifier indicating that they belong to cgroup. * cgroup_subsys->subsys_id should always equal the matching cgroup_subsys_id enum; however, we require each controller to initialize it and then BUG if they don't match, which is a bit silly. This patch cleans up cgroup_subsys names and initialization by doing the followings. * cgroup_subsys_id enums are now postfixed with _cgrp_id, and each cgroup_subsys with _cgrp_subsys. * With the above, renaming subsys identifiers to match the userland visible names doesn't cause any naming conflicts. All non-matching identifiers are renamed to match the official names. cpu_cgroup -> cpu mem_cgroup -> memory perf -> perf_event * controllers no longer need to initialize ->subsys_id and ->name. They're generated in cgroup core and set automatically during boot. * Redundant cgroup_subsys declarations removed. * While updating BUG_ON()s in cgroup_init_early(), convert them to WARN()s. BUGging that early during boot is stupid - the kernel can't print anything, even through serial console and the trap handler doesn't even link stack frame properly for back-tracing. This patch doesn't introduce any behavior changes. v2: Rebased on top of fe1217c4f3f7 ("net: net_cls: move cgroupfs classid handling into core"). Signed-off-by: Tejun Heo Acked-by: Neil Horman Acked-by: "David S. Miller" Acked-by: "Rafael J. Wysocki" Acked-by: Michal Hocko Acked-by: Peter Zijlstra Acked-by: Aristeu Rozanski Acked-by: Ingo Molnar Acked-by: Li Zefan Cc: Johannes Weiner Cc: Balbir Singh Cc: KAMEZAWA Hiroyuki Cc: Serge E. Hallyn Cc: Vivek Goyal Cc: Thomas Graf --- block/blk-cgroup.c | 8 +++----- block/blk-cgroup.h | 2 +- 2 files changed, 4 insertions(+), 6 deletions(-) (limited to 'block') diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 660d419918a7..1cef07cf9c21 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -906,16 +906,14 @@ static int blkcg_can_attach(struct cgroup_subsys_state *css, return ret; } -struct cgroup_subsys blkio_subsys = { - .name = "blkio", +struct cgroup_subsys blkio_cgrp_subsys = { .css_alloc = blkcg_css_alloc, .css_offline = blkcg_css_offline, .css_free = blkcg_css_free, .can_attach = blkcg_can_attach, - .subsys_id = blkio_subsys_id, .base_cftypes = blkcg_files, }; -EXPORT_SYMBOL_GPL(blkio_subsys); +EXPORT_SYMBOL_GPL(blkio_cgrp_subsys); /** * blkcg_activate_policy - activate a blkcg policy on a request_queue @@ -1105,7 +1103,7 @@ int blkcg_policy_register(struct blkcg_policy *pol) /* everything is in place, add intf files for the new policy */ if (pol->cftypes) - WARN_ON(cgroup_add_cftypes(&blkio_subsys, pol->cftypes)); + WARN_ON(cgroup_add_cftypes(&blkio_cgrp_subsys, pol->cftypes)); ret = 0; out_unlock: mutex_unlock(&blkcg_pol_mutex); diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 86154eab9523..453b528c8e19 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -186,7 +186,7 @@ static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css) static inline struct blkcg *task_blkcg(struct task_struct *tsk) { - return css_to_blkcg(task_css(tsk, blkio_subsys_id)); + return css_to_blkcg(task_css(tsk, blkio_cgrp_id)); } static inline struct blkcg *bio_blkcg(struct bio *bio) -- cgit v1.2.3 From 5f46990787e2721b4db190ddc8af6fdbe8f010d7 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 11 Feb 2014 11:52:48 -0500 Subject: cgroup: update the meaning of cftype->max_write_len cftype->max_write_len is used to extend the maximum size of writes. It's interpreted in such a way that the actual maximum size is one less than the specified value. The default size is defined by CGROUP_LOCAL_BUFFER_SIZE. Its interpretation is quite confusing - its value is decremented by 1 and then compared for equality with max size, which means that the actual default size is CGROUP_LOCAL_BUFFER_SIZE - 2, which is 62 chars. There's no point in having a limit that low. Update its definition so that it means the actual string length sans termination and anything below PAGE_SIZE-1 is treated as PAGE_SIZE-1. .max_write_len for "release_agent" is updated to PATH_MAX-1 and cgroup_release_agent_write() is updated so that the redundant strlen() check is removed and it uses strlcpy() instead of strcpy(). .max_write_len initializations in blk-throttle.c and cfq-iosched.c are no longer necessary and removed. The one in cpuset is kept unchanged as it's an approximated value to begin with. This will also make transition to kernfs smoother. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- block/blk-throttle.c | 4 ---- block/cfq-iosched.c | 3 --- 2 files changed, 7 deletions(-) (limited to 'block') diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 1474c3ab7e72..861c363e4129 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1425,28 +1425,24 @@ static struct cftype throtl_files[] = { .private = offsetof(struct throtl_grp, bps[READ]), .seq_show = tg_print_conf_u64, .write_string = tg_set_conf_u64, - .max_write_len = 256, }, { .name = "throttle.write_bps_device", .private = offsetof(struct throtl_grp, bps[WRITE]), .seq_show = tg_print_conf_u64, .write_string = tg_set_conf_u64, - .max_write_len = 256, }, { .name = "throttle.read_iops_device", .private = offsetof(struct throtl_grp, iops[READ]), .seq_show = tg_print_conf_uint, .write_string = tg_set_conf_uint, - .max_write_len = 256, }, { .name = "throttle.write_iops_device", .private = offsetof(struct throtl_grp, iops[WRITE]), .seq_show = tg_print_conf_uint, .write_string = tg_set_conf_uint, - .max_write_len = 256, }, { .name = "throttle.io_service_bytes", diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 744833b630c6..461187943392 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1838,7 +1838,6 @@ static struct cftype cfq_blkcg_files[] = { .flags = CFTYPE_ONLY_ON_ROOT, .seq_show = cfqg_print_leaf_weight_device, .write_string = cfqg_set_leaf_weight_device, - .max_write_len = 256, }, { .name = "weight", @@ -1853,7 +1852,6 @@ static struct cftype cfq_blkcg_files[] = { .flags = CFTYPE_NOT_ON_ROOT, .seq_show = cfqg_print_weight_device, .write_string = cfqg_set_weight_device, - .max_write_len = 256, }, { .name = "weight", @@ -1866,7 +1864,6 @@ static struct cftype cfq_blkcg_files[] = { .name = "leaf_weight_device", .seq_show = cfqg_print_leaf_weight_device, .write_string = cfqg_set_leaf_weight_device, - .max_write_len = 256, }, { .name = "leaf_weight", -- cgit v1.2.3 From e61734c55c24cdf11b07e52a74aec4dc4a7f4bd0 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 12 Feb 2014 09:29:50 -0500 Subject: cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo Acked-by: Peter Zijlstra Acked-by: Michal Hocko Acked-by: Li Zefan Cc: Fengguang Wu Cc: Ingo Molnar Cc: Johannes Weiner Cc: Balbir Singh Cc: KAMEZAWA Hiroyuki --- block/blk-cgroup.h | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'block') diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 453b528c8e19..15a8d640de57 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -241,12 +241,16 @@ static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) */ static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen) { - int ret; + char *p; - ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen); - if (ret) + p = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen); + if (!p) { strncpy(buf, "", buflen); - return ret; + return -ENAMETOOLONG; + } + + memmove(buf, p, buf + buflen - p); + return 0; } /** -- cgit v1.2.3 From 924f0d9a2078f49ff331bb43196ec5afadc16b8f Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 13 Feb 2014 06:58:41 -0500 Subject: cgroup: drop @skip_css from cgroup_taskset_for_each() If !NULL, @skip_css makes cgroup_taskset_for_each() skip the matching css. The intention of the interface is to make it easy to skip css's (cgroup_subsys_states) which already match the migration target; however, this is entirely unnecessary as migration taskset doesn't include tasks which are already in the target cgroup. Drop @skip_css from cgroup_taskset_for_each(). Signed-off-by: Tejun Heo Acked-by: Li Zefan Cc: Peter Zijlstra Cc: Paul Mackerras Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Daniel Borkmann --- block/blk-cgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'block') diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 1cef07cf9c21..4aefd46d7d95 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -894,7 +894,7 @@ static int blkcg_can_attach(struct cgroup_subsys_state *css, int ret = 0; /* task_lock() is needed to avoid races with exit_io_context() */ - cgroup_taskset_for_each(task, css, tset) { + cgroup_taskset_for_each(task, tset) { task_lock(task); ioc = task->io_context; if (ioc && atomic_read(&ioc->nr_tasks) > 1) -- cgit v1.2.3 From 4d3bb511b5f9980fc3e9ae5939ebc475b231d3fc Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 19 Mar 2014 10:23:54 -0400 Subject: cgroup: drop const from @buffer of cftype->write_string() cftype->write_string() just passes on the writeable buffer from kernfs and there's no reason to add const restriction on the buffer. The only thing const achieves is unnecessarily complicating parsing of the buffer. Drop const from @buffer. Signed-off-by: Tejun Heo Acked-by: Li Zefan Cc: Peter Zijlstra Cc: Paul Mackerras Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Daniel Borkmann Cc: Michal Hocko Cc: Johannes Weiner Cc: Balbir Singh Cc: KAMEZAWA Hiroyuki --- block/blk-throttle.c | 4 ++-- block/cfq-iosched.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) (limited to 'block') diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 861c363e4129..033745cd7fba 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1408,13 +1408,13 @@ static int tg_set_conf(struct cgroup_subsys_state *css, struct cftype *cft, } static int tg_set_conf_u64(struct cgroup_subsys_state *css, struct cftype *cft, - const char *buf) + char *buf) { return tg_set_conf(css, cft, buf, true); } static int tg_set_conf_uint(struct cgroup_subsys_state *css, struct cftype *cft, - const char *buf) + char *buf) { return tg_set_conf(css, cft, buf, false); } diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 461187943392..f5de45b6af36 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1701,13 +1701,13 @@ static int __cfqg_set_weight_device(struct cgroup_subsys_state *css, } static int cfqg_set_weight_device(struct cgroup_subsys_state *css, - struct cftype *cft, const char *buf) + struct cftype *cft, char *buf) { return __cfqg_set_weight_device(css, cft, buf, false); } static int cfqg_set_leaf_weight_device(struct cgroup_subsys_state *css, - struct cftype *cft, const char *buf) + struct cftype *cft, char *buf) { return __cfqg_set_weight_device(css, cft, buf, true); } -- cgit v1.2.3