Currently, cgroup_pidlist_open() skips seq_open() and pidlist loading
if the file is opened write-only, which is a sensible optimization as
pidlist loading can be costly and there often are occasions where
tasks or cgroup.procs is opened write-only. However, pidlist init and
release are planned to be moved to cgroup_pidlist_start/stop()
respectively which would make this optimization unnecessary.
This patch removes the optimization and always fully initializes
pidlist files regardless of open mode. This will help moving pidlist
handling to start/stop by unifying rw paths and removes the need for
specifying cftype->release() in addition to .release in
cgroup_pidlist_operations as file->f_op is now always overridden. As
pidlist files were the only user of cftype->release(), the next patch
will remove the method.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
kernel/cgroup.c | 13 +------------
1 file changed, 1 insertion(+), 12 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index be42967..61a5e2e 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3778,12 +3778,7 @@ static void cgroup_release_pid_array(struct cgroup_pidlist *l)
static int cgroup_pidlist_release(struct inode *inode, struct file *file)
{
struct cgroup_pidlist *l;
- if (!(file->f_mode & FMODE_READ))
- return 0;
- /*
- * the seq_file will only be initialized if the file was opened for
- * reading; hence we check if it's not null only in that case.
- */
+
l = ((struct seq_file *)file->private_data)->private;
cgroup_release_pid_array(l);
return seq_release(inode, file);
@@ -3808,10 +3803,6 @@ static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type)
struct cgroup_pidlist *l;
int retval;
- /* Nothing to do for write-only files */
- if (!(file->f_mode & FMODE_READ))
- return 0;
-
/* have the array populated */
retval = pidlist_array_load(cgrp, type, &l);
if (retval)
@@ -3891,7 +3882,6 @@ static struct cftype cgroup_base_files[] = {
.name = "cgroup.procs",
.open = cgroup_procs_open,
.write_u64 = cgroup_procs_write,
- .release = cgroup_pidlist_release,
.mode = S_IRUGO | S_IWUSR,
},
{
@@ -3916,7 +3906,6 @@ static struct cftype cgroup_base_files[] = {
.flags = CFTYPE_INSANE, /* use "procs" instead */
.open = cgroup_tasks_open,
.write_u64 = cgroup_tasks_write,
- .release = cgroup_pidlist_release,
.mode = S_IRUGO | S_IWUSR,
},
{
--
1.8.4.2
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