diff options
| -rw-r--r-- | include/linux/cgroup.h | 6 | ||||
| -rw-r--r-- | kernel/cgroup.c | 112 |
2 files changed, 68 insertions, 50 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index b32a0f8ae9ad..8b9a594f0c92 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -434,7 +434,6 @@ struct cftype { */ struct cgroup_subsys *ss; - int (*open)(struct inode *inode, struct file *file); /* * read_u64() is a shortcut for the common case of returning a * single integer. Use it in place of read() @@ -448,6 +447,11 @@ struct cftype { /* generic seq_file read interface */ int (*seq_show)(struct seq_file *sf, void *v); + /* optional ops, implement all or none */ + void *(*seq_start)(struct seq_file *sf, loff_t *ppos); + void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos); + void (*seq_stop)(struct seq_file *sf, void *v); + /* * write_u64() is a shortcut for the common case of accepting * a single integer (as parsed by simple_strtoull) from diff --git a/kernel/cgroup.c b/kernel/cgroup.c index c45e63328a0a..f9ae38a95af2 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2286,6 +2286,45 @@ out_free: * supports string->u64 maps, but can be extended in future. */ +static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) +{ + struct cftype *cft = seq_cft(seq); + + if (cft->seq_start) { + return cft->seq_start(seq, ppos); + } else { + /* + * The same behavior and code as single_open(). Returns + * !NULL if pos is at the beginning; otherwise, NULL. + */ + return NULL + !*ppos; + } +} + +static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos) +{ + struct cftype *cft = seq_cft(seq); + + if (cft->seq_next) { + return cft->seq_next(seq, v, ppos); + } else { + /* + * The same behavior and code as single_open(), always + * terminate after the initial read. + */ + ++*ppos; + return NULL; + } +} + +static void cgroup_seqfile_stop(struct seq_file *seq, void *v) +{ + struct cftype *cft = seq_cft(seq); + + if (cft->seq_stop) + cft->seq_stop(seq, v); +} + static int cgroup_seqfile_show(struct seq_file *m, void *arg) { struct cftype *cft = seq_cft(m); @@ -2303,12 +2342,20 @@ static int cgroup_seqfile_show(struct seq_file *m, void *arg) return 0; } +static struct seq_operations cgroup_seq_operations = { + .start = cgroup_seqfile_start, + .next = cgroup_seqfile_next, + .stop = cgroup_seqfile_stop, + .show = cgroup_seqfile_show, +}; + static int cgroup_file_open(struct inode *inode, struct file *file) { struct cfent *cfe = __d_cfe(file->f_dentry); struct cftype *cft = __d_cft(file->f_dentry); struct cgroup *cgrp = __d_cgrp(cfe->dentry->d_parent); struct cgroup_subsys_state *css; + struct cgroup_open_file *of; int err; err = generic_file_open(inode, file); @@ -2338,24 +2385,16 @@ static int cgroup_file_open(struct inode *inode, struct file *file) WARN_ON_ONCE(cfe->css && cfe->css != css); cfe->css = css; - if (cft->open) { - err = cft->open(inode, file); - } else { - struct cgroup_open_file *of; - - err = -ENOMEM; - of = kzalloc(sizeof(*of), GFP_KERNEL); - if (of) { - of->cfe = cfe; - err = single_open(file, cgroup_seqfile_show, of); - if (err) - kfree(of); - } + of = __seq_open_private(file, &cgroup_seq_operations, + sizeof(struct cgroup_open_file)); + if (of) { + of->cfe = cfe; + return 0; } - if (css->ss && err) + if (css->ss) css_put(css); - return err; + return -ENOMEM; } static int cgroup_file_release(struct inode *inode, struct file *file) @@ -2365,8 +2404,7 @@ static int cgroup_file_release(struct inode *inode, struct file *file) if (css->ss) css_put(css); - kfree(((struct seq_file *)file->private_data)->private); - return single_release(inode, file); + return seq_release_private(inode, file); } /* @@ -3777,36 +3815,6 @@ static const struct seq_operations cgroup_pidlist_seq_operations = { .show = cgroup_pidlist_show, }; -static const struct file_operations cgroup_pidlist_operations = { - .read = seq_read, - .llseek = seq_lseek, - .write = cgroup_file_write, - .release = seq_release_private, -}; - -/* - * The following functions handle opens on a file that displays a pidlist - * (tasks or procs). Prepare an array of the process/thread IDs of whoever's - * in the cgroup. - */ -/* helper function for the two below it */ -static int cgroup_pidlist_open(struct inode *unused, struct file *file) -{ - struct cfent *cfe = __d_cfe(file->f_dentry); - struct cgroup_open_file *of; - - /* configure file information */ - file->f_op = &cgroup_pidlist_operations; - - of = __seq_open_private(file, &cgroup_pidlist_seq_operations, - sizeof(*of)); - if (!of) - return -ENOMEM; - - of->cfe = cfe; - return 0; -} - static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, struct cftype *cft) { @@ -3860,7 +3868,10 @@ static int cgroup_clone_children_write(struct cgroup_subsys_state *css, static struct cftype cgroup_base_files[] = { { .name = "cgroup.procs", - .open = cgroup_pidlist_open, + .seq_start = cgroup_pidlist_start, + .seq_next = cgroup_pidlist_next, + .seq_stop = cgroup_pidlist_stop, + .seq_show = cgroup_pidlist_show, .private = CGROUP_FILE_PROCS, .write_u64 = cgroup_procs_write, .mode = S_IRUGO | S_IWUSR, @@ -3885,7 +3896,10 @@ static struct cftype cgroup_base_files[] = { { .name = "tasks", .flags = CFTYPE_INSANE, /* use "procs" instead */ - .open = cgroup_pidlist_open, + .seq_start = cgroup_pidlist_start, + .seq_next = cgroup_pidlist_next, + .seq_stop = cgroup_pidlist_stop, + .seq_show = cgroup_pidlist_show, .private = CGROUP_FILE_TASKS, .write_u64 = cgroup_tasks_write, .mode = S_IRUGO | S_IWUSR, |