diff options
| -rw-r--r-- | include/linux/cgroup.h | 11 | ||||
| -rw-r--r-- | kernel/cgroup.c | 96 |
2 files changed, 76 insertions, 31 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 665fa70..20411d2 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -179,14 +179,11 @@ struct cgroup { */ struct list_head release_list; - /* pids_mutex protects the fields below */ + /* pids_mutex protects pids_list and cached pid arrays. */ struct rw_semaphore pids_mutex; - /* Array of process ids in the cgroup */ - pid_t *tasks_pids; - /* How many files are using the current tasks_pids array */ - int pids_use_count; - /* Length of the current tasks_pids array */ - int pids_length; + + /* Linked list of struct cgroup_pids */ + struct list_head pids_list; /* For RCU-protected deletion */ struct rcu_head rcu_head; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 3737a68..250dac0 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -47,6 +47,7 @@ #include <linux/hash.h> #include <linux/namei.h> #include <linux/smp_lock.h> +#include <linux/pid_namespace.h> #include <asm/atomic.h> @@ -960,6 +961,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp) INIT_LIST_HEAD(&cgrp->children); INIT_LIST_HEAD(&cgrp->css_sets); INIT_LIST_HEAD(&cgrp->release_list); + INIT_LIST_HEAD(&cgrp->pids_list); init_rwsem(&cgrp->pids_mutex); } static void init_cgroup_root(struct cgroupfs_root *root) @@ -2201,12 +2203,30 @@ err: return ret; } +/* + * Cache pids for all threads in the same pid namespace that are + * opening the same "tasks" file. + */ +struct cgroup_pids { + /* The node in cgrp->pids_list */ + struct list_head list; + /* The cgroup those pids belong to */ + struct cgroup *cgrp; + /* The namepsace those pids belong to */ + struct pid_namespace *ns; + /* Array of process ids in the cgroup */ + pid_t *tasks_pids; + /* How many files are using the this tasks_pids array */ + int use_count; + /* Length of the current tasks_pids array */ + int length; +}; + static int cmppid(const void *a, const void *b) { return *(pid_t *)a - *(pid_t *)b; } - /* * seq_file methods for the "tasks" file. The seq_file position is the * next pid to display; the seq_file iterator is a pointer to the pid @@ -2221,45 +2241,47 @@ static void *cgroup_tasks_start(struct seq_file *s, loff_t *pos) * after a seek to the start). Use a binary-search to find the * next pid to display, if any */ - struct cgroup *cgrp = s->private; + struct cgroup_pids *cp = s->private; + struct cgroup *cgrp = cp->cgrp; int index = 0, pid = *pos; int *iter; down_read(&cgrp->pids_mutex); if (pid) { - int end = cgrp->pids_length; + int end = cp->length; while (index < end) { int mid = (index + end) / 2; - if (cgrp->tasks_pids[mid] == pid) { + if (cp->tasks_pids[mid] == pid) { index = mid; break; - } else if (cgrp->tasks_pids[mid] <= pid) + } else if (cp->tasks_pids[mid] <= pid) index = mid + 1; else end = mid; } } /* If we're off the end of the array, we're done */ - if (index >= cgrp->pids_length) + if (index >= cp->length) return NULL; /* Update the abstract position to be the actual pid that we found */ - iter = cgrp->tasks_pids + index; + iter = cp->tasks_pids + index; *pos = *iter; return iter; } static void cgroup_tasks_stop(struct seq_file *s, void *v) { - struct cgroup *cgrp = s->private; + struct cgroup_pids *cp = s->private; + struct cgroup *cgrp = cp->cgrp; up_read(&cgrp->pids_mutex); } static void *cgroup_tasks_next(struct seq_file *s, void *v, loff_t *pos) { - struct cgroup *cgrp = s->private; + struct cgroup_pids *cp = s->private; int *p = v; - int *end = cgrp->tasks_pids + cgrp->pids_length; + int *end = cp->tasks_pids + cp->length; /* * Advance to the next pid in the array. If this goes off the @@ -2286,26 +2308,33 @@ static struct seq_operations cgroup_tasks_seq_operations = { .show = cgroup_tasks_show, }; -static void release_cgroup_pid_array(struct cgroup *cgrp) +static void release_cgroup_pid_array(struct cgroup_pids *cp) { + struct cgroup *cgrp = cp->cgrp; + down_write(&cgrp->pids_mutex); - BUG_ON(!cgrp->pids_use_count); - if (!--cgrp->pids_use_count) { - kfree(cgrp->tasks_pids); - cgrp->tasks_pids = NULL; - cgrp->pids_length = 0; + BUG_ON(!cp->use_count); + if (!--cp->use_count) { + list_del(&cp->list); + put_pid_ns(cp->ns); + kfree(cp->tasks_pids); + kfree(cp); } up_write(&cgrp->pids_mutex); } static int cgroup_tasks_release(struct inode *inode, struct file *file) { - struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); + struct seq_file *seq; + struct cgroup_pids *cp; if (!(file->f_mode & FMODE_READ)) return 0; - release_cgroup_pid_array(cgrp); + seq = file->private_data; + cp = seq->private; + + release_cgroup_pid_array(cp); return seq_release(inode, file); } @@ -2324,6 +2353,8 @@ static struct file_operations cgroup_tasks_operations = { static int cgroup_tasks_open(struct inode *unused, struct file *file) { struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); + struct pid_namespace *ns = current->nsproxy->pid_ns; + struct cgroup_pids *cp; pid_t *pidarray; int npids; int retval; @@ -2350,20 +2381,37 @@ static int cgroup_tasks_open(struct inode *unused, struct file *file) * array if necessary */ down_write(&cgrp->pids_mutex); - kfree(cgrp->tasks_pids); - cgrp->tasks_pids = pidarray; - cgrp->pids_length = npids; - cgrp->pids_use_count++; + + list_for_each_entry(cp, &cgrp->pids_list, list) { + if (ns == cp->ns) + goto found; + } + + cp = kzalloc(sizeof(*cp), GFP_KERNEL); + if (!cp) { + up_write(&cgrp->pids_mutex); + kfree(pidarray); + return -ENOMEM; + } + cp->cgrp = cgrp; + cp->ns = ns; + get_pid_ns(ns); + list_add(&cp->list, &cgrp->pids_list); +found: + kfree(cp->tasks_pids); + cp->tasks_pids = pidarray; + cp->length = npids; + cp->use_count++; up_write(&cgrp->pids_mutex); file->f_op = &cgroup_tasks_operations; retval = seq_open(file, &cgroup_tasks_seq_operations); if (retval) { - release_cgroup_pid_array(cgrp); + release_cgroup_pid_array(cp); return retval; } - ((struct seq_file *)file->private_data)->private = cgrp; + ((struct seq_file *)file->private_data)->private = cp; return 0; } |
