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authorPaul Menage <menage@google.com>2008-07-25 01:46:58 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-25 10:53:35 -0700
commitdb3b14978abc02041046ed8353f0899cb58ffffc (patch)
tree355ba027c6354bd13bcbb5318e8478b3de4599e9 /include
parentce16b49d37e748574f7fabc2726268d542d0aa1a (diff)
cgroup files: add write_string cgroup control file method
This patch adds a write_string() method for cgroups control files. The semantics are that a buffer is copied from userspace to kernelspace and the handler function invoked on that buffer. The buffer is guaranteed to be nul-terminated, and no longer than max_write_len (defaulting to 64 bytes if unspecified). Later patches will convert existing raw file write handlers in control group subsystems to use this method. Signed-off-by: Paul Menage <menage@google.com> Cc: Paul Jackson <pj@sgi.com> Cc: Pavel Emelyanov <xemul@openvz.org> Acked-by: Balbir Singh <balbir@in.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/cgroup.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 88a734edccbc..f5379455bb59 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -205,6 +205,13 @@ struct cftype {
* subsystem, followed by a period */
char name[MAX_CFTYPE_NAME];
int private;
+
+ /*
+ * If non-zero, defines the maximum length of string that can
+ * be passed to write_string; defaults to 64
+ */
+ size_t max_write_len;
+
int (*open)(struct inode *inode, struct file *file);
ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft,
struct file *file,
@@ -249,6 +256,13 @@ struct cftype {
int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val);
/*
+ * write_string() is passed a nul-terminated kernelspace
+ * buffer of maximum length determined by max_write_len.
+ * Returns 0 or -ve error code.
+ */
+ int (*write_string)(struct cgroup *cgrp, struct cftype *cft,
+ const char *buffer);
+ /*
* trigger() callback can be used to get some kick from the
* userspace, when the actual string written is not important
* at all. The private field can be used to determine the