Commit 84eea842 authored by Paul Menage's avatar Paul Menage Committed by Linus Torvalds
Browse files

cgroups: misc cleanups to write_string patchset 



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: default avatarPaul 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: default avatarSerge Hallyn <serue@us.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e788e066

include/linux/cgroup.h

+2 −2
Original line number Diff line number Diff line
@@ -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);

kernel/cgroup.c

+12 −9
Original line number Diff line number Diff line
@@ -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);

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