The patch titled
Subject: kernel: cgroup: add poll file operation
has been added to the -mm tree. Its filename is
kernel-cgroup-add-poll-file-operation.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kernel-cgroup-add-poll-file-operation.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kernel-cgroup-add-poll-file-operation.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: kernel: cgroup: add poll file operation
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@xxxxxxxxxx
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Dennis Zhou <dennis@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/cgroup-defs.h | 4 ++++
kernel/cgroup/cgroup.c | 12 ++++++++++++
2 files changed, 16 insertions(+)
--- a/include/linux/cgroup-defs.h~kernel-cgroup-add-poll-file-operation
+++ a/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
@@ -574,6 +575,9 @@ 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
--- a/kernel/cgroup/cgroup.c~kernel-cgroup-add-poll-file-operation
+++ a/kernel/cgroup/cgroup.c
@@ -3533,6 +3533,16 @@ static ssize_t cgroup_file_write(struct
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);
@@ -3571,6 +3581,7 @@ static struct kernfs_ops cgroup_kf_singl
.open = cgroup_file_open,
.release = cgroup_file_release,
.write = cgroup_file_write,
+ .poll = cgroup_file_poll,
.seq_show = cgroup_seqfile_show,
};
@@ -3579,6 +3590,7 @@ 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,
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
fs-kernfs-add-poll-file-operation.patch
kernel-cgroup-add-poll-file-operation.patch
