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-rw-r--r--include/linux/cgroup.h11
-rw-r--r--kernel/cgroup.c96
2 files changed, 76 insertions, 31 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 665fa70e4094..20411d2876f8 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -179,14 +179,11 @@ struct cgroup {
179 */ 179 */
180 struct list_head release_list; 180 struct list_head release_list;
181 181
182 /* pids_mutex protects the fields below */ 182 /* pids_mutex protects pids_list and cached pid arrays. */
183 struct rw_semaphore pids_mutex; 183 struct rw_semaphore pids_mutex;
184 /* Array of process ids in the cgroup */ 184
185 pid_t *tasks_pids; 185 /* Linked list of struct cgroup_pids */
186 /* How many files are using the current tasks_pids array */ 186 struct list_head pids_list;
187 int pids_use_count;
188 /* Length of the current tasks_pids array */
189 int pids_length;
190 187
191 /* For RCU-protected deletion */ 188 /* For RCU-protected deletion */
192 struct rcu_head rcu_head; 189 struct rcu_head rcu_head;
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 3737a682cdf5..250dac05680f 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -47,6 +47,7 @@
47#include <linux/hash.h> 47#include <linux/hash.h>
48#include <linux/namei.h> 48#include <linux/namei.h>
49#include <linux/smp_lock.h> 49#include <linux/smp_lock.h>
50#include <linux/pid_namespace.h>
50 51
51#include <asm/atomic.h> 52#include <asm/atomic.h>
52 53
@@ -960,6 +961,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
960 INIT_LIST_HEAD(&cgrp->children); 961 INIT_LIST_HEAD(&cgrp->children);
961 INIT_LIST_HEAD(&cgrp->css_sets); 962 INIT_LIST_HEAD(&cgrp->css_sets);
962 INIT_LIST_HEAD(&cgrp->release_list); 963 INIT_LIST_HEAD(&cgrp->release_list);
964 INIT_LIST_HEAD(&cgrp->pids_list);
963 init_rwsem(&cgrp->pids_mutex); 965 init_rwsem(&cgrp->pids_mutex);
964} 966}
965static void init_cgroup_root(struct cgroupfs_root *root) 967static void init_cgroup_root(struct cgroupfs_root *root)
@@ -2201,12 +2203,30 @@ err:
2201 return ret; 2203 return ret;
2202} 2204}
2203 2205
2206/*
2207 * Cache pids for all threads in the same pid namespace that are
2208 * opening the same "tasks" file.
2209 */
2210struct cgroup_pids {
2211 /* The node in cgrp->pids_list */
2212 struct list_head list;
2213 /* The cgroup those pids belong to */
2214 struct cgroup *cgrp;
2215 /* The namepsace those pids belong to */
2216 struct pid_namespace *ns;
2217 /* Array of process ids in the cgroup */
2218 pid_t *tasks_pids;
2219 /* How many files are using the this tasks_pids array */
2220 int use_count;
2221 /* Length of the current tasks_pids array */
2222 int length;
2223};
2224
2204static int cmppid(const void *a, const void *b) 2225static int cmppid(const void *a, const void *b)
2205{ 2226{
2206 return *(pid_t *)a - *(pid_t *)b; 2227 return *(pid_t *)a - *(pid_t *)b;
2207} 2228}
2208 2229
2209
2210/* 2230/*
2211 * seq_file methods for the "tasks" file. The seq_file position is the 2231 * seq_file methods for the "tasks" file. The seq_file position is the
2212 * next pid to display; the seq_file iterator is a pointer to the pid 2232 * 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)
2221 * after a seek to the start). Use a binary-search to find the 2241 * after a seek to the start). Use a binary-search to find the
2222 * next pid to display, if any 2242 * next pid to display, if any
2223 */ 2243 */
2224 struct cgroup *cgrp = s->private; 2244 struct cgroup_pids *cp = s->private;
2245 struct cgroup *cgrp = cp->cgrp;
2225 int index = 0, pid = *pos; 2246 int index = 0, pid = *pos;
2226 int *iter; 2247 int *iter;
2227 2248
2228 down_read(&cgrp->pids_mutex); 2249 down_read(&cgrp->pids_mutex);
2229 if (pid) { 2250 if (pid) {
2230 int end = cgrp->pids_length; 2251 int end = cp->length;
2231 2252
2232 while (index < end) { 2253 while (index < end) {
2233 int mid = (index + end) / 2; 2254 int mid = (index + end) / 2;
2234 if (cgrp->tasks_pids[mid] == pid) { 2255 if (cp->tasks_pids[mid] == pid) {
2235 index = mid; 2256 index = mid;
2236 break; 2257 break;
2237 } else if (cgrp->tasks_pids[mid] <= pid) 2258 } else if (cp->tasks_pids[mid] <= pid)
2238 index = mid + 1; 2259 index = mid + 1;
2239 else 2260 else
2240 end = mid; 2261 end = mid;
2241 } 2262 }
2242 } 2263 }
2243 /* If we're off the end of the array, we're done */ 2264 /* If we're off the end of the array, we're done */
2244 if (index >= cgrp->pids_length) 2265 if (index >= cp->length)
2245 return NULL; 2266 return NULL;
2246 /* Update the abstract position to be the actual pid that we found */ 2267 /* Update the abstract position to be the actual pid that we found */
2247 iter = cgrp->tasks_pids + index; 2268 iter = cp->tasks_pids + index;
2248 *pos = *iter; 2269 *pos = *iter;
2249 return iter; 2270 return iter;
2250} 2271}
2251 2272
2252static void cgroup_tasks_stop(struct seq_file *s, void *v) 2273static void cgroup_tasks_stop(struct seq_file *s, void *v)
2253{ 2274{
2254 struct cgroup *cgrp = s->private; 2275 struct cgroup_pids *cp = s->private;
2276 struct cgroup *cgrp = cp->cgrp;
2255 up_read(&cgrp->pids_mutex); 2277 up_read(&cgrp->pids_mutex);
2256} 2278}
2257 2279
2258static void *cgroup_tasks_next(struct seq_file *s, void *v, loff_t *pos) 2280static void *cgroup_tasks_next(struct seq_file *s, void *v, loff_t *pos)
2259{ 2281{
2260 struct cgroup *cgrp = s->private; 2282 struct cgroup_pids *cp = s->private;
2261 int *p = v; 2283 int *p = v;
2262 int *end = cgrp->tasks_pids + cgrp->pids_length; 2284 int *end = cp->tasks_pids + cp->length;
2263 2285
2264 /* 2286 /*
2265 * Advance to the next pid in the array. If this goes off the 2287 * 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 = {
2286 .show = cgroup_tasks_show, 2308 .show = cgroup_tasks_show,
2287}; 2309};
2288 2310
2289static void release_cgroup_pid_array(struct cgroup *cgrp) 2311static void release_cgroup_pid_array(struct cgroup_pids *cp)
2290{ 2312{
2313 struct cgroup *cgrp = cp->cgrp;
2314
2291 down_write(&cgrp->pids_mutex); 2315 down_write(&cgrp->pids_mutex);
2292 BUG_ON(!cgrp->pids_use_count); 2316 BUG_ON(!cp->use_count);
2293 if (!--cgrp->pids_use_count) { 2317 if (!--cp->use_count) {
2294 kfree(cgrp->tasks_pids); 2318 list_del(&cp->list);
2295 cgrp->tasks_pids = NULL; 2319 put_pid_ns(cp->ns);
2296 cgrp->pids_length = 0; 2320 kfree(cp->tasks_pids);
2321 kfree(cp);
2297 } 2322 }
2298 up_write(&cgrp->pids_mutex); 2323 up_write(&cgrp->pids_mutex);
2299} 2324}
2300 2325
2301static int cgroup_tasks_release(struct inode *inode, struct file *file) 2326static int cgroup_tasks_release(struct inode *inode, struct file *file)
2302{ 2327{
2303 struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); 2328 struct seq_file *seq;
2329 struct cgroup_pids *cp;
2304 2330
2305 if (!(file->f_mode & FMODE_READ)) 2331 if (!(file->f_mode & FMODE_READ))
2306 return 0; 2332 return 0;
2307 2333
2308 release_cgroup_pid_array(cgrp); 2334 seq = file->private_data;
2335 cp = seq->private;
2336
2337 release_cgroup_pid_array(cp);
2309 return seq_release(inode, file); 2338 return seq_release(inode, file);
2310} 2339}
2311 2340
@@ -2324,6 +2353,8 @@ static struct file_operations cgroup_tasks_operations = {
2324static int cgroup_tasks_open(struct inode *unused, struct file *file) 2353static int cgroup_tasks_open(struct inode *unused, struct file *file)
2325{ 2354{
2326 struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); 2355 struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
2356 struct pid_namespace *ns = current->nsproxy->pid_ns;
2357 struct cgroup_pids *cp;
2327 pid_t *pidarray; 2358 pid_t *pidarray;
2328 int npids; 2359 int npids;
2329 int retval; 2360 int retval;
@@ -2350,20 +2381,37 @@ static int cgroup_tasks_open(struct inode *unused, struct file *file)
2350 * array if necessary 2381 * array if necessary
2351 */ 2382 */
2352 down_write(&cgrp->pids_mutex); 2383 down_write(&cgrp->pids_mutex);
2353 kfree(cgrp->tasks_pids); 2384
2354 cgrp->tasks_pids = pidarray; 2385 list_for_each_entry(cp, &cgrp->pids_list, list) {
2355 cgrp->pids_length = npids; 2386 if (ns == cp->ns)
2356 cgrp->pids_use_count++; 2387 goto found;
2388 }
2389
2390 cp = kzalloc(sizeof(*cp), GFP_KERNEL);
2391 if (!cp) {
2392 up_write(&cgrp->pids_mutex);
2393 kfree(pidarray);
2394 return -ENOMEM;
2395 }
2396 cp->cgrp = cgrp;
2397 cp->ns = ns;
2398 get_pid_ns(ns);
2399 list_add(&cp->list, &cgrp->pids_list);
2400found:
2401 kfree(cp->tasks_pids);
2402 cp->tasks_pids = pidarray;
2403 cp->length = npids;
2404 cp->use_count++;
2357 up_write(&cgrp->pids_mutex); 2405 up_write(&cgrp->pids_mutex);
2358 2406
2359 file->f_op = &cgroup_tasks_operations; 2407 file->f_op = &cgroup_tasks_operations;
2360 2408
2361 retval = seq_open(file, &cgroup_tasks_seq_operations); 2409 retval = seq_open(file, &cgroup_tasks_seq_operations);
2362 if (retval) { 2410 if (retval) {
2363 release_cgroup_pid_array(cgrp); 2411 release_cgroup_pid_array(cp);
2364 return retval; 2412 return retval;
2365 } 2413 }
2366 ((struct seq_file *)file->private_data)->private = cgrp; 2414 ((struct seq_file *)file->private_data)->private = cp;
2367 return 0; 2415 return 0;
2368} 2416}
2369 2417