From: Liu Xinpeng liuxp11@chinatelecom.cn
mainline inclusion from mainline-v5.4 commit dc50537bdd1a0804fa2cbc990565ee9a944e66fa category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I47QS2 CVE: NA
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Cgroup has a standardized poll/notification mechanism for waking all pollers on all fds when a filesystem node changes. To allow polling for custom events, add a .poll callback that can override the default.
This is in preparation for pollable cgroup pressure files which have per-fd trigger configurations.
Link: http://lkml.kernel.org/r/20190124211518.244221-3-surenb@google.com Signed-off-by: Johannes Weiner hannes@cmpxchg.org Signed-off-by: Suren Baghdasaryan surenb@google.com Cc: Dennis Zhou dennis@kernel.org Cc: Ingo Molnar mingo@redhat.com Cc: Jens Axboe axboe@kernel.dk Cc: Li Zefan lizefan@huawei.com Cc: Peter Zijlstra peterz@infradead.org Cc: Tejun Heo tj@kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Liu Xinpeng liuxp11@chinatelecom.cn Signed-off-by: Ctyun Kernel ctyuncommiter01@chinatelecom.cn --- include/linux/cgroup-defs.h | 4 ++++ kernel/cgroup/cgroup.c | 12 ++++++++++++ 2 files changed, 16 insertions(+)
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index daf2233f1660..454ea4f351c9 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -32,6 +32,7 @@ struct kernfs_node; struct kernfs_ops; struct kernfs_open_file; struct seq_file; +struct poll_table_struct;
#define MAX_CGROUP_TYPE_NAMELEN 32 #define MAX_CGROUP_ROOT_NAMELEN 64 @@ -579,6 +580,9 @@ struct cftype { ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off);
+ __poll_t (*poll)(struct kernfs_open_file *of, + struct poll_table_struct *pt); + #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lock_class_key lockdep_key; #endif diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 71ac258e7521..1c893a04f418 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -3506,6 +3506,16 @@ static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, return ret ?: nbytes; }
+static __poll_t cgroup_file_poll(struct kernfs_open_file *of, poll_table *pt) +{ + struct cftype *cft = of->kn->priv; + + if (cft->poll) + return cft->poll(of, pt); + + return kernfs_generic_poll(of, pt); +} + static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) { return seq_cft(seq)->seq_start(seq, ppos); @@ -3544,6 +3554,7 @@ static struct kernfs_ops cgroup_kf_single_ops = { .open = cgroup_file_open, .release = cgroup_file_release, .write = cgroup_file_write, + .poll = cgroup_file_poll, .seq_show = cgroup_seqfile_show, };
@@ -3552,6 +3563,7 @@ static struct kernfs_ops cgroup_kf_ops = { .open = cgroup_file_open, .release = cgroup_file_release, .write = cgroup_file_write, + .poll = cgroup_file_poll, .seq_start = cgroup_seqfile_start, .seq_next = cgroup_seqfile_next, .seq_stop = cgroup_seqfile_stop,