From: Tejun Heo tj@kernel.org
commit 0d2b5955b36250a9428c832664f2079cbf723bec upstream.
of->priv is currently used by each interface file implementation to store private information. This patch collects the current two private data usages into struct cgroup_file_ctx which is allocated and freed by the common path. This allows generic private data which applies to multiple files, which will be used to in the following patch.
Note that cgroup_procs iterator is now embedded as procs.iter in the new cgroup_file_ctx so that it doesn't need to be allocated and freed separately.
v2: union dropped from cgroup_file_ctx and the procs iterator is embedded in cgroup_file_ctx as suggested by Linus.
v3: Michal pointed out that cgroup1's procs pidlist uses of->priv too. Converted. Didn't change to embedded allocation as cgroup1 pidlists get stored for caching.
Signed-off-by: Tejun Heo tj@kernel.org Cc: Linus Torvalds torvalds@linux-foundation.org Reviewed-by: Michal Koutný mkoutny@suse.com [mkoutny: v5.10: modify cgroup.pressure handlers, adjust context] Signed-off-by: Michal Koutný mkoutny@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [OP: backport to v4.19: drop changes to cgroup_pressure_*() functions] Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/cgroup/cgroup-internal.h | 17 ++++++++++++++++ kernel/cgroup/cgroup-v1.c | 26 +++++++++++++----------- kernel/cgroup/cgroup.c | 42 ++++++++++++++++++++++++---------------- 3 files changed, 57 insertions(+), 28 deletions(-)
--- a/kernel/cgroup/cgroup-internal.h +++ b/kernel/cgroup/cgroup-internal.h @@ -34,6 +34,23 @@ extern char trace_cgroup_path[TRACE_CGRO } \ } while (0)
+struct cgroup_pidlist; + +struct cgroup_file_ctx { + struct { + void *trigger; + } psi; + + struct { + bool started; + struct css_task_iter iter; + } procs; + + struct { + struct cgroup_pidlist *pidlist; + } procs1; +}; + /* * A cgroup can be associated with multiple css_sets as different tasks may * belong to different cgroups on different hierarchies. In the other --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -426,6 +426,7 @@ static void *cgroup_pidlist_start(struct * next pid to display, if any */ struct kernfs_open_file *of = s->private; + struct cgroup_file_ctx *ctx = of->priv; struct cgroup *cgrp = seq_css(s)->cgroup; struct cgroup_pidlist *l; enum cgroup_filetype type = seq_cft(s)->private; @@ -435,25 +436,24 @@ static void *cgroup_pidlist_start(struct mutex_lock(&cgrp->pidlist_mutex);
/* - * !NULL @of->priv indicates that this isn't the first start() - * after open. If the matching pidlist is around, we can use that. - * Look for it. Note that @of->priv can't be used directly. It - * could already have been destroyed. + * !NULL @ctx->procs1.pidlist indicates that this isn't the first + * start() after open. If the matching pidlist is around, we can use + * that. Look for it. Note that @ctx->procs1.pidlist can't be used + * directly. It could already have been destroyed. */ - if (of->priv) - of->priv = cgroup_pidlist_find(cgrp, type); + if (ctx->procs1.pidlist) + ctx->procs1.pidlist = cgroup_pidlist_find(cgrp, type);
/* * Either this is the first start() after open or the matching * pidlist has been destroyed inbetween. Create a new one. */ - if (!of->priv) { - ret = pidlist_array_load(cgrp, type, - (struct cgroup_pidlist **)&of->priv); + if (!ctx->procs1.pidlist) { + ret = pidlist_array_load(cgrp, type, &ctx->procs1.pidlist); if (ret) return ERR_PTR(ret); } - l = of->priv; + l = ctx->procs1.pidlist;
if (pid) { int end = l->length; @@ -481,7 +481,8 @@ static void *cgroup_pidlist_start(struct static void cgroup_pidlist_stop(struct seq_file *s, void *v) { struct kernfs_open_file *of = s->private; - struct cgroup_pidlist *l = of->priv; + struct cgroup_file_ctx *ctx = of->priv; + struct cgroup_pidlist *l = ctx->procs1.pidlist;
if (l) mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, @@ -492,7 +493,8 @@ static void cgroup_pidlist_stop(struct s static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) { struct kernfs_open_file *of = s->private; - struct cgroup_pidlist *l = of->priv; + struct cgroup_file_ctx *ctx = of->priv; + struct cgroup_pidlist *l = ctx->procs1.pidlist; pid_t *p = v; pid_t *end = l->list + l->length; /* --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -3451,18 +3451,31 @@ static int cpu_stat_show(struct seq_file static int cgroup_file_open(struct kernfs_open_file *of) { struct cftype *cft = of->kn->priv; + struct cgroup_file_ctx *ctx; + int ret;
- if (cft->open) - return cft->open(of); - return 0; + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); + if (!ctx) + return -ENOMEM; + of->priv = ctx; + + if (!cft->open) + return 0; + + ret = cft->open(of); + if (ret) + kfree(ctx); + return ret; }
static void cgroup_file_release(struct kernfs_open_file *of) { struct cftype *cft = of->kn->priv; + struct cgroup_file_ctx *ctx = of->priv;
if (cft->release) cft->release(of); + kfree(ctx); }
static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, @@ -4376,21 +4389,21 @@ void css_task_iter_end(struct css_task_i
static void cgroup_procs_release(struct kernfs_open_file *of) { - if (of->priv) { - css_task_iter_end(of->priv); - kfree(of->priv); - } + struct cgroup_file_ctx *ctx = of->priv; + + if (ctx->procs.started) + css_task_iter_end(&ctx->procs.iter); }
static void *cgroup_procs_next(struct seq_file *s, void *v, loff_t *pos) { struct kernfs_open_file *of = s->private; - struct css_task_iter *it = of->priv; + struct cgroup_file_ctx *ctx = of->priv;
if (pos) (*pos)++;
- return css_task_iter_next(it); + return css_task_iter_next(&ctx->procs.iter); }
static void *__cgroup_procs_start(struct seq_file *s, loff_t *pos, @@ -4398,21 +4411,18 @@ static void *__cgroup_procs_start(struct { struct kernfs_open_file *of = s->private; struct cgroup *cgrp = seq_css(s)->cgroup; - struct css_task_iter *it = of->priv; + struct cgroup_file_ctx *ctx = of->priv; + struct css_task_iter *it = &ctx->procs.iter;
/* * When a seq_file is seeked, it's always traversed sequentially * from position 0, so we can simply keep iterating on !0 *pos. */ - if (!it) { + if (!ctx->procs.started) { if (WARN_ON_ONCE((*pos))) return ERR_PTR(-EINVAL); - - it = kzalloc(sizeof(*it), GFP_KERNEL); - if (!it) - return ERR_PTR(-ENOMEM); - of->priv = it; css_task_iter_start(&cgrp->self, iter_flags, it); + ctx->procs.started = true; } else if (!(*pos)) { css_task_iter_end(it); css_task_iter_start(&cgrp->self, iter_flags, it);