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cgroups: misc cleanups to write_string patchset

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This patch contains cleanups suggested by reviewers for the recent
write_string() patchset:

- pair cgroup_lock_live_group() with cgroup_unlock() in cgroup.c for
  clarity, rather than directly unlocking cgroup_mutex.

- make the return type of cgroup_lock_live_group() a bool

- use a #define'd constant for the local buffer size in read/write functions

Signed-off-by: Paul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: 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>
This commit is contained in:
Paul Menage 2008-07-25 01:47:00 -07:00 committed by Linus Torvalds
parent e788e066c6
commit 84eea84288
2 changed files with 14 additions and 11 deletions
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4
include/linux/cgroup.h
View file

@ -21,11 +21,13 @@
struct cgroupfs_root;
struct cgroup_subsys;
struct inode;
struct cgroup;
extern int cgroup_init_early(void);
extern int cgroup_init(void);
extern void cgroup_init_smp(void);
extern void cgroup_lock(void);
extern bool cgroup_lock_live_group(struct cgroup *cgrp);
extern void cgroup_unlock(void);
extern void cgroup_fork(struct task_struct *p);
extern void cgroup_fork_callbacks(struct task_struct *p);
@ -295,8 +297,6 @@ int cgroup_add_files(struct cgroup *cgrp,
int cgroup_is_removed(const struct cgroup *cgrp);
int cgroup_lock_live_group(struct cgroup *cgrp);
int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
int cgroup_task_count(const struct cgroup *cgrp);

21
kernel/cgroup.c
View file

@ -1329,10 +1329,10 @@ enum cgroup_filetype {
* cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive.
* @cgrp: the cgroup to be checked for liveness
*
* Returns true (with lock held) on success, or false (with no lock
* held) on failure.
* On success, returns true; the lock should be later released with
* cgroup_unlock(). On failure returns false with no lock held.
*/
int cgroup_lock_live_group(struct cgroup *cgrp)
bool cgroup_lock_live_group(struct cgroup *cgrp)
{
mutex_lock(&cgroup_mutex);
if (cgroup_is_removed(cgrp)) {
@ -1349,7 +1349,7 @@ static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft,
if (!cgroup_lock_live_group(cgrp))
return -ENODEV;
strcpy(cgrp->root->release_agent_path, buffer);
mutex_unlock(&cgroup_mutex);
cgroup_unlock();
return 0;
}
@ -1360,16 +1360,19 @@ static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft,
return -ENODEV;
seq_puts(seq, cgrp->root->release_agent_path);
seq_putc(seq, '\n');
mutex_unlock(&cgroup_mutex);
cgroup_unlock();
return 0;
}
/* A buffer size big enough for numbers or short strings */
#define CGROUP_LOCAL_BUFFER_SIZE 64
static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft,
struct file *file,
const char __user *userbuf,
size_t nbytes, loff_t *unused_ppos)
{
char buffer[64];
char buffer[CGROUP_LOCAL_BUFFER_SIZE];
int retval = 0;
char *end;
@ -1403,7 +1406,7 @@ static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft,
const char __user *userbuf,
size_t nbytes, loff_t *unused_ppos)
{
char local_buffer[64];
char local_buffer[CGROUP_LOCAL_BUFFER_SIZE];
int retval = 0;
size_t max_bytes = cft->max_write_len;
char *buffer = local_buffer;
@ -1518,7 +1521,7 @@ static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft,
char __user *buf, size_t nbytes,
loff_t *ppos)
{
char tmp[64];
char tmp[CGROUP_LOCAL_BUFFER_SIZE];
u64 val = cft->read_u64(cgrp, cft);
int len = sprintf(tmp, "%llu\n", (unsigned long long) val);
@ -1530,7 +1533,7 @@ static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft,
char __user *buf, size_t nbytes,
loff_t *ppos)
{
char tmp[64];
char tmp[CGROUP_LOCAL_BUFFER_SIZE];
s64 val = cft->read_s64(cgrp, cft);
int len = sprintf(tmp, "%lld\n", (long long) val);