This patch moves the write handler for the cgroups notify_on_release
file into a separate handler. This handler requires no cgroups locking
since it relies on atomic bitops for synchronization.

Signed-off-by: Paul Menage

---
kernel/cgroup.c | 27 +++++++++++++++------------
1 file changed, 15 insertions(+), 12 deletions(-)

Index: cgroup-2.6.25-mm1/kernel/cgroup.c
================================================== =================
--- cgroup-2.6.25-mm1.orig/kernel/cgroup.c
+++ cgroup-2.6.25-mm1/kernel/cgroup.c
@@ -1440,13 +1440,6 @@ static ssize_t cgroup_common_file_write(
case FILE_TASKLIST:
retval = attach_task_by_pid(cgrp, buffer);
break;
- case FILE_NOTIFY_ON_RELEASE:
- clear_bit(CGRP_RELEASABLE, &cgrp->flags);
- if (simple_strtoul(buffer, NULL, 10) != 0)
- set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
- else
- clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
- break;
default:
retval = -EINVAL;
goto out2;
@@ -2275,6 +2268,18 @@ static u64 cgroup_read_notify_on_release
return notify_on_release(cgrp);
}

+static int cgroup_write_notify_on_release(struct cgroup *cgrp,
+ struct cftype *cft,
+ u64 val)
+{
+ clear_bit(CGRP_RELEASABLE, &cgrp->flags);
+ if (val)
+ set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
+ else
+ clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
+ return 0;
+}
+
/*
* for the common functions, 'private' gives the type of file
*/
@@ -2291,7 +2296,7 @@ static struct cftype files[] = {
{
.name = "notify_on_release",
.read_u64 = cgroup_read_notify_on_release,
- .write = cgroup_common_file_write,
+ .write_u64 = cgroup_write_notify_on_release,
.private = FILE_NOTIFY_ON_RELEASE,
},
};

--
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