X-Git-Url: http://git.agner.ch/gitweb/?p=linux-drm-fsl-dcu.git;a=blobdiff_plain;f=block%2Fblk-cgroup.c;h=9da02c021ebe2ed296cbdf8560d5bbf2ecd1c48f;hp=9f97da52d006281b1ab3e2911d85934216e3931a;hb=4c7d83e8a8106d90d4eff971c8d070f718ac4f9c;hpb=05a8256c586ab75bcd6b793737b2022a1a98cb1e diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 9f97da52d006..9da02c021ebe 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -29,6 +29,14 @@ #define MAX_KEY_LEN 100 +/* + * blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation. + * blkcg_pol_register_mutex nests outside of it and synchronizes entire + * policy [un]register operations including cgroup file additions / + * removals. Putting cgroup file registration outside blkcg_pol_mutex + * allows grabbing it from cgroup callbacks. + */ +static DEFINE_MUTEX(blkcg_pol_register_mutex); static DEFINE_MUTEX(blkcg_pol_mutex); struct blkcg blkcg_root; @@ -38,6 +46,8 @@ struct cgroup_subsys_state * const blkcg_root_css = &blkcg_root.css; static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; +static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */ + static bool blkcg_policy_enabled(struct request_queue *q, const struct blkcg_policy *pol) { @@ -453,20 +463,7 @@ static int blkcg_reset_stats(struct cgroup_subsys_state *css, struct blkcg_gq *blkg; int i; - /* - * XXX: We invoke cgroup_add/rm_cftypes() under blkcg_pol_mutex - * which ends up putting cgroup's internal cgroup_tree_mutex under - * it; however, cgroup_tree_mutex is nested above cgroup file - * active protection and grabbing blkcg_pol_mutex from a cgroup - * file operation creates a possible circular dependency. cgroup - * internal locking is planned to go through further simplification - * and this issue should go away soon. For now, let's trylock - * blkcg_pol_mutex and restart the write on failure. - * - * http://lkml.kernel.org/g/5363C04B.4010400@oracle.com - */ - if (!mutex_trylock(&blkcg_pol_mutex)) - return restart_syscall(); + mutex_lock(&blkcg_pol_mutex); spin_lock_irq(&blkcg->lock); /* @@ -822,8 +819,17 @@ static void blkcg_css_free(struct cgroup_subsys_state *css) { struct blkcg *blkcg = css_to_blkcg(css); - if (blkcg != &blkcg_root) + mutex_lock(&blkcg_pol_mutex); + list_del(&blkcg->all_blkcgs_node); + mutex_unlock(&blkcg_pol_mutex); + + if (blkcg != &blkcg_root) { + int i; + + for (i = 0; i < BLKCG_MAX_POLS; i++) + kfree(blkcg->pd[i]); kfree(blkcg); + } } static struct cgroup_subsys_state * @@ -833,6 +839,8 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css) struct cgroup_subsys_state *ret; int i; + mutex_lock(&blkcg_pol_mutex); + if (!parent_css) { blkcg = &blkcg_root; goto done; @@ -875,14 +883,17 @@ done: #ifdef CONFIG_CGROUP_WRITEBACK INIT_LIST_HEAD(&blkcg->cgwb_list); #endif + list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs); + + mutex_unlock(&blkcg_pol_mutex); return &blkcg->css; free_pd_blkcg: for (i--; i >= 0; i--) kfree(blkcg->pd[i]); - free_blkcg: kfree(blkcg); + mutex_unlock(&blkcg_pol_mutex); return ret; } @@ -1037,10 +1048,8 @@ int blkcg_activate_policy(struct request_queue *q, const struct blkcg_policy *pol) { LIST_HEAD(pds); - LIST_HEAD(cpds); struct blkcg_gq *blkg; struct blkg_policy_data *pd, *nd; - struct blkcg_policy_data *cpd, *cnd; int cnt = 0, ret; if (blkcg_policy_enabled(q, pol)) @@ -1053,10 +1062,7 @@ int blkcg_activate_policy(struct request_queue *q, cnt++; spin_unlock_irq(q->queue_lock); - /* - * Allocate per-blkg and per-blkcg policy data - * for all existing blkgs. - */ + /* allocate per-blkg policy data for all existing blkgs */ while (cnt--) { pd = kzalloc_node(pol->pd_size, GFP_KERNEL, q->node); if (!pd) { @@ -1064,15 +1070,6 @@ int blkcg_activate_policy(struct request_queue *q, goto out_free; } list_add_tail(&pd->alloc_node, &pds); - - if (!pol->cpd_size) - continue; - cpd = kzalloc_node(pol->cpd_size, GFP_KERNEL, q->node); - if (!cpd) { - ret = -ENOMEM; - goto out_free; - } - list_add_tail(&cpd->alloc_node, &cpds); } /* @@ -1082,32 +1079,17 @@ int blkcg_activate_policy(struct request_queue *q, spin_lock_irq(q->queue_lock); list_for_each_entry(blkg, &q->blkg_list, q_node) { - if (WARN_ON(list_empty(&pds)) || - WARN_ON(pol->cpd_size && list_empty(&cpds))) { + if (WARN_ON(list_empty(&pds))) { /* umm... this shouldn't happen, just abort */ ret = -ENOMEM; goto out_unlock; } - cpd = list_first_entry(&cpds, struct blkcg_policy_data, - alloc_node); - list_del_init(&cpd->alloc_node); pd = list_first_entry(&pds, struct blkg_policy_data, alloc_node); list_del_init(&pd->alloc_node); /* grab blkcg lock too while installing @pd on @blkg */ spin_lock(&blkg->blkcg->lock); - if (!pol->cpd_size) - goto no_cpd; - if (!blkg->blkcg->pd[pol->plid]) { - /* Per-policy per-blkcg data */ - blkg->blkcg->pd[pol->plid] = cpd; - cpd->plid = pol->plid; - pol->cpd_init_fn(blkg->blkcg); - } else { /* must free it as it has already been extracted */ - kfree(cpd); - } -no_cpd: blkg->pd[pol->plid] = pd; pd->blkg = blkg; pd->plid = pol->plid; @@ -1124,8 +1106,6 @@ out_free: blk_queue_bypass_end(q); list_for_each_entry_safe(pd, nd, &pds, alloc_node) kfree(pd); - list_for_each_entry_safe(cpd, cnd, &cpds, alloc_node) - kfree(cpd); return ret; } EXPORT_SYMBOL_GPL(blkcg_activate_policy); @@ -1162,8 +1142,6 @@ void blkcg_deactivate_policy(struct request_queue *q, kfree(blkg->pd[pol->plid]); blkg->pd[pol->plid] = NULL; - kfree(blkg->blkcg->pd[pol->plid]); - blkg->blkcg->pd[pol->plid] = NULL; spin_unlock(&blkg->blkcg->lock); } @@ -1182,11 +1160,13 @@ EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); */ int blkcg_policy_register(struct blkcg_policy *pol) { + struct blkcg *blkcg; int i, ret; if (WARN_ON(pol->pd_size < sizeof(struct blkg_policy_data))) return -EINVAL; + mutex_lock(&blkcg_pol_register_mutex); mutex_lock(&blkcg_pol_mutex); /* find an empty slot */ @@ -1195,19 +1175,49 @@ int blkcg_policy_register(struct blkcg_policy *pol) if (!blkcg_policy[i]) break; if (i >= BLKCG_MAX_POLS) - goto out_unlock; + goto err_unlock; - /* register and update blkgs */ + /* register @pol */ pol->plid = i; - blkcg_policy[i] = pol; + blkcg_policy[pol->plid] = pol; + + /* allocate and install cpd's */ + if (pol->cpd_size) { + list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { + struct blkcg_policy_data *cpd; + + cpd = kzalloc(pol->cpd_size, GFP_KERNEL); + if (!cpd) { + mutex_unlock(&blkcg_pol_mutex); + goto err_free_cpds; + } + + blkcg->pd[pol->plid] = cpd; + cpd->plid = pol->plid; + pol->cpd_init_fn(blkcg); + } + } + + mutex_unlock(&blkcg_pol_mutex); /* everything is in place, add intf files for the new policy */ if (pol->cftypes) WARN_ON(cgroup_add_legacy_cftypes(&blkio_cgrp_subsys, pol->cftypes)); - ret = 0; -out_unlock: + mutex_unlock(&blkcg_pol_register_mutex); + return 0; + +err_free_cpds: + if (pol->cpd_size) { + list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { + kfree(blkcg->pd[pol->plid]); + blkcg->pd[pol->plid] = NULL; + } + } + blkcg_policy[pol->plid] = NULL; +err_unlock: mutex_unlock(&blkcg_pol_mutex); + mutex_unlock(&blkcg_pol_register_mutex); return ret; } EXPORT_SYMBOL_GPL(blkcg_policy_register); @@ -1220,7 +1230,9 @@ EXPORT_SYMBOL_GPL(blkcg_policy_register); */ void blkcg_policy_unregister(struct blkcg_policy *pol) { - mutex_lock(&blkcg_pol_mutex); + struct blkcg *blkcg; + + mutex_lock(&blkcg_pol_register_mutex); if (WARN_ON(blkcg_policy[pol->plid] != pol)) goto out_unlock; @@ -1229,9 +1241,19 @@ void blkcg_policy_unregister(struct blkcg_policy *pol) if (pol->cftypes) cgroup_rm_cftypes(pol->cftypes); - /* unregister and update blkgs */ + /* remove cpds and unregister */ + mutex_lock(&blkcg_pol_mutex); + + if (pol->cpd_size) { + list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { + kfree(blkcg->pd[pol->plid]); + blkcg->pd[pol->plid] = NULL; + } + } blkcg_policy[pol->plid] = NULL; -out_unlock: + mutex_unlock(&blkcg_pol_mutex); +out_unlock: + mutex_unlock(&blkcg_pol_register_mutex); } EXPORT_SYMBOL_GPL(blkcg_policy_unregister);