diff options
| -rw-r--r-- | include/linux/cgroup.h | 8 | ||||
| -rw-r--r-- | kernel/cgroup.c | 42 |
2 files changed, 46 insertions, 4 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index e2dd44f68f97..e95143c884b2 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -125,6 +125,14 @@ struct cftype { ssize_t (*write) (struct cgroup *cont, struct cftype *cft, struct file *file, const char __user *buf, size_t nbytes, loff_t *ppos); + + /* + * write_uint() is a shortcut for the common case of accepting + * a single integer (as parsed by simple_strtoull) from + * userspace. Use in place of write(); return 0 or error. + */ + int (*write_uint) (struct cgroup *cont, struct cftype *cft, u64 val); + int (*release) (struct inode *inode, struct file *file); }; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 356c40d5d20a..f4c4dce9558f 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -829,6 +829,39 @@ enum cgroup_filetype { FILE_TASKLIST, }; +static ssize_t cgroup_write_uint(struct cgroup *cont, struct cftype *cft, + struct file *file, + const char __user *userbuf, + size_t nbytes, loff_t *unused_ppos) +{ + char buffer[64]; + int retval = 0; + u64 val; + char *end; + + if (!nbytes) + return -EINVAL; + if (nbytes >= sizeof(buffer)) + return -E2BIG; + if (copy_from_user(buffer, userbuf, nbytes)) + return -EFAULT; + + buffer[nbytes] = 0; /* nul-terminate */ + + /* strip newline if necessary */ + if (nbytes && (buffer[nbytes-1] == '\n')) + buffer[nbytes-1] = 0; + val = simple_strtoull(buffer, &end, 0); + if (*end) + return -EINVAL; + + /* Pass to subsystem */ + retval = cft->write_uint(cont, cft, val); + if (!retval) + retval = nbytes; + return retval; +} + static ssize_t cgroup_common_file_write(struct cgroup *cont, struct cftype *cft, struct file *file, @@ -886,10 +919,11 @@ static ssize_t cgroup_file_write(struct file *file, const char __user *buf, if (!cft) return -ENODEV; - if (!cft->write) - return -EINVAL; - - return cft->write(cont, cft, file, buf, nbytes, ppos); + if (cft->write) + return cft->write(cont, cft, file, buf, nbytes, ppos); + if (cft->write_uint) + return cgroup_write_uint(cont, cft, file, buf, nbytes, ppos); + return -EINVAL; } static ssize_t cgroup_read_uint(struct cgroup *cont, struct cftype *cft, |