X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=kernel%2Fcgroup.c;h=657f8f8d93a5fa947e79d0b8567a9c5288f425d9;hb=61f10fad1947116055c694321d9d8f21152c0582;hp=15ac0e1e4f4de9dde14a6fe17e9b3d6e059a4baf;hpb=53ffe3b440aa85af6fc4eda09b2d44bcdd312d4d;p=linux-2.6-omap-h63xx.git diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 15ac0e1e4f4..657f8f8d93a 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -45,6 +45,7 @@ #include #include #include +#include #include @@ -89,11 +90,7 @@ struct cgroupfs_root { /* Hierarchy-specific flags */ unsigned long flags; - /* The path to use for release notifications. No locking - * between setting and use - so if userspace updates this - * while child cgroups exist, you could miss a - * notification. We ensure that it's always a valid - * NUL-terminated string */ + /* The path to use for release notifications. */ char release_agent_path[PATH_MAX]; }; @@ -118,7 +115,7 @@ static int root_count; * extra work in the fork/exit path if none of the subsystems need to * be called. */ -static int need_forkexit_callback; +static int need_forkexit_callback __read_mostly; static int need_mm_owner_callback __read_mostly; /* convenient tests for these bits */ @@ -220,7 +217,7 @@ static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) * task until after the first call to cgroup_iter_start(). This * reduces the fork()/exit() overhead for people who have cgroups * compiled into their kernel but not actually in use */ -static int use_task_css_set_links; +static int use_task_css_set_links __read_mostly; /* When we create or destroy a css_set, the operation simply * takes/releases a reference count on all the cgroups referenced @@ -241,17 +238,20 @@ static int use_task_css_set_links; */ static void unlink_css_set(struct css_set *cg) { + struct cg_cgroup_link *link; + struct cg_cgroup_link *saved_link; + write_lock(&css_set_lock); hlist_del(&cg->hlist); css_set_count--; - while (!list_empty(&cg->cg_links)) { - struct cg_cgroup_link *link; - link = list_entry(cg->cg_links.next, - struct cg_cgroup_link, cg_link_list); + + list_for_each_entry_safe(link, saved_link, &cg->cg_links, + cg_link_list) { list_del(&link->cg_link_list); list_del(&link->cgrp_link_list); kfree(link); } + write_unlock(&css_set_lock); } @@ -363,15 +363,14 @@ static struct css_set *find_existing_css_set( static int allocate_cg_links(int count, struct list_head *tmp) { struct cg_cgroup_link *link; + struct cg_cgroup_link *saved_link; int i; INIT_LIST_HEAD(tmp); for (i = 0; i < count; i++) { link = kmalloc(sizeof(*link), GFP_KERNEL); if (!link) { - while (!list_empty(tmp)) { - link = list_entry(tmp->next, - struct cg_cgroup_link, - cgrp_link_list); + list_for_each_entry_safe(link, saved_link, tmp, + cgrp_link_list) { list_del(&link->cgrp_link_list); kfree(link); } @@ -384,11 +383,10 @@ static int allocate_cg_links(int count, struct list_head *tmp) static void free_cg_links(struct list_head *tmp) { - while (!list_empty(tmp)) { - struct cg_cgroup_link *link; - link = list_entry(tmp->next, - struct cg_cgroup_link, - cgrp_link_list); + struct cg_cgroup_link *link; + struct cg_cgroup_link *saved_link; + + list_for_each_entry_safe(link, saved_link, tmp, cgrp_link_list) { list_del(&link->cgrp_link_list); kfree(link); } @@ -415,11 +413,11 @@ static struct css_set *find_css_set( /* First see if we already have a cgroup group that matches * the desired set */ - write_lock(&css_set_lock); + read_lock(&css_set_lock); res = find_existing_css_set(oldcg, cgrp, template); if (res) get_css_set(res); - write_unlock(&css_set_lock); + read_unlock(&css_set_lock); if (res) return res; @@ -507,10 +505,6 @@ static struct css_set *find_css_set( * knows that the cgroup won't be removed, as cgroup_rmdir() * needs that mutex. * - * The cgroup_common_file_write handler for operations that modify - * the cgroup hierarchy holds cgroup_mutex across the entire operation, - * single threading all such cgroup modifications across the system. - * * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't * (usually) take cgroup_mutex. These are the two most performance * critical pieces of code here. The exception occurs on cgroup_exit(), @@ -1093,6 +1087,8 @@ static void cgroup_kill_sb(struct super_block *sb) { struct cgroupfs_root *root = sb->s_fs_info; struct cgroup *cgrp = &root->top_cgroup; int ret; + struct cg_cgroup_link *link; + struct cg_cgroup_link *saved_link; BUG_ON(!root); @@ -1112,10 +1108,9 @@ static void cgroup_kill_sb(struct super_block *sb) { * root cgroup */ write_lock(&css_set_lock); - while (!list_empty(&cgrp->css_sets)) { - struct cg_cgroup_link *link; - link = list_entry(cgrp->css_sets.next, - struct cg_cgroup_link, cgrp_link_list); + + list_for_each_entry_safe(link, saved_link, &cgrp->css_sets, + cgrp_link_list) { list_del(&link->cg_link_list); list_del(&link->cgrp_link_list); kfree(link); @@ -1281,18 +1276,14 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) } /* - * Attach task with pid 'pid' to cgroup 'cgrp'. Call with - * cgroup_mutex, may take task_lock of task + * Attach task with pid 'pid' to cgroup 'cgrp'. Call with cgroup_mutex + * held. May take task_lock of task */ -static int attach_task_by_pid(struct cgroup *cgrp, char *pidbuf) +static int attach_task_by_pid(struct cgroup *cgrp, u64 pid) { - pid_t pid; struct task_struct *tsk; int ret; - if (sscanf(pidbuf, "%d", &pid) != 1) - return -EIO; - if (pid) { rcu_read_lock(); tsk = find_task_by_vpid(pid); @@ -1318,6 +1309,16 @@ static int attach_task_by_pid(struct cgroup *cgrp, char *pidbuf) return ret; } +static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) +{ + int ret; + if (!cgroup_lock_live_group(cgrp)) + return -ENODEV; + ret = attach_task_by_pid(cgrp, pid); + cgroup_unlock(); + return ret; +} + /* The various types of files and directories in a cgroup file system */ enum cgroup_filetype { FILE_ROOT, @@ -1327,12 +1328,54 @@ enum cgroup_filetype { FILE_RELEASE_AGENT, }; +/** + * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. + * @cgrp: the cgroup to be checked for liveness + * + * On success, returns true; the lock should be later released with + * cgroup_unlock(). On failure returns false with no lock held. + */ +bool cgroup_lock_live_group(struct cgroup *cgrp) +{ + mutex_lock(&cgroup_mutex); + if (cgroup_is_removed(cgrp)) { + mutex_unlock(&cgroup_mutex); + return false; + } + return true; +} + +static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, + const char *buffer) +{ + BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); + if (!cgroup_lock_live_group(cgrp)) + return -ENODEV; + strcpy(cgrp->root->release_agent_path, buffer); + cgroup_unlock(); + return 0; +} + +static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft, + struct seq_file *seq) +{ + if (!cgroup_lock_live_group(cgrp)) + return -ENODEV; + seq_puts(seq, cgrp->root->release_agent_path); + seq_putc(seq, '\n'); + 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; @@ -1361,68 +1404,36 @@ static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft, return retval; } -static ssize_t cgroup_common_file_write(struct cgroup *cgrp, - struct cftype *cft, - struct file *file, - const char __user *userbuf, - size_t nbytes, loff_t *unused_ppos) +static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft, + struct file *file, + const char __user *userbuf, + size_t nbytes, loff_t *unused_ppos) { - enum cgroup_filetype type = cft->private; - char *buffer; + char local_buffer[CGROUP_LOCAL_BUFFER_SIZE]; int retval = 0; + size_t max_bytes = cft->max_write_len; + char *buffer = local_buffer; - if (nbytes >= PATH_MAX) + if (!max_bytes) + max_bytes = sizeof(local_buffer) - 1; + if (nbytes >= max_bytes) return -E2BIG; - - /* +1 for nul-terminator */ - buffer = kmalloc(nbytes + 1, GFP_KERNEL); - if (buffer == NULL) - return -ENOMEM; - - if (copy_from_user(buffer, userbuf, nbytes)) { - retval = -EFAULT; - goto out1; + /* Allocate a dynamic buffer if we need one */ + if (nbytes >= sizeof(local_buffer)) { + buffer = kmalloc(nbytes + 1, GFP_KERNEL); + if (buffer == NULL) + return -ENOMEM; } - buffer[nbytes] = 0; /* nul-terminate */ - strstrip(buffer); /* strip -just- trailing whitespace */ - - mutex_lock(&cgroup_mutex); + if (nbytes && copy_from_user(buffer, userbuf, nbytes)) + return -EFAULT; - /* - * This was already checked for in cgroup_file_write(), but - * check again now we're holding cgroup_mutex. - */ - if (cgroup_is_removed(cgrp)) { - retval = -ENODEV; - goto out2; - } - - switch (type) { - case FILE_TASKLIST: - retval = attach_task_by_pid(cgrp, buffer); - break; - case FILE_NOTIFY_ON_RELEASE: - clear_bit(CGRP_RELEASABLE, &cgrp->flags); - if (simple_strtoul(buffer, NULL, 10) != 0) - set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); - else - clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); - break; - case FILE_RELEASE_AGENT: - BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); - strcpy(cgrp->root->release_agent_path, buffer); - break; - default: - retval = -EINVAL; - goto out2; - } - - if (retval == 0) + buffer[nbytes] = 0; /* nul-terminate */ + strstrip(buffer); + retval = cft->write_string(cgrp, cft, buffer); + if (!retval) retval = nbytes; -out2: - mutex_unlock(&cgroup_mutex); -out1: - kfree(buffer); + if (buffer != local_buffer) + kfree(buffer); return retval; } @@ -1438,6 +1449,8 @@ static ssize_t cgroup_file_write(struct file *file, const char __user *buf, return cft->write(cgrp, cft, file, buf, nbytes, ppos); if (cft->write_u64 || cft->write_s64) return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos); + if (cft->write_string) + return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos); if (cft->trigger) { int ret = cft->trigger(cgrp, (unsigned int)cft->private); return ret ? ret : nbytes; @@ -1450,7 +1463,7 @@ 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); @@ -1462,56 +1475,13 @@ 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); return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); } -static ssize_t cgroup_common_file_read(struct cgroup *cgrp, - struct cftype *cft, - struct file *file, - char __user *buf, - size_t nbytes, loff_t *ppos) -{ - enum cgroup_filetype type = cft->private; - char *page; - ssize_t retval = 0; - char *s; - - if (!(page = (char *)__get_free_page(GFP_KERNEL))) - return -ENOMEM; - - s = page; - - switch (type) { - case FILE_RELEASE_AGENT: - { - struct cgroupfs_root *root; - size_t n; - mutex_lock(&cgroup_mutex); - root = cgrp->root; - n = strnlen(root->release_agent_path, - sizeof(root->release_agent_path)); - n = min(n, (size_t) PAGE_SIZE); - strncpy(s, root->release_agent_path, n); - mutex_unlock(&cgroup_mutex); - s += n; - break; - } - default: - retval = -EINVAL; - goto out; - } - *s++ = '\n'; - - retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page); -out: - free_page((unsigned long)page); - return retval; -} - static ssize_t cgroup_file_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) { @@ -1560,7 +1530,7 @@ static int cgroup_seqfile_show(struct seq_file *m, void *arg) return cft->read_seq_string(state->cgroup, cft, m); } -int cgroup_seqfile_release(struct inode *inode, struct file *file) +static int cgroup_seqfile_release(struct inode *inode, struct file *file) { struct seq_file *seq = file->private_data; kfree(seq->private); @@ -1569,6 +1539,7 @@ int cgroup_seqfile_release(struct inode *inode, struct file *file) static struct file_operations cgroup_seqfile_operations = { .read = seq_read, + .write = cgroup_file_write, .llseek = seq_lseek, .release = cgroup_seqfile_release, }; @@ -1756,15 +1727,11 @@ int cgroup_add_files(struct cgroup *cgrp, int cgroup_task_count(const struct cgroup *cgrp) { int count = 0; - struct list_head *l; + struct cg_cgroup_link *link; read_lock(&css_set_lock); - l = cgrp->css_sets.next; - while (l != &cgrp->css_sets) { - struct cg_cgroup_link *link = - list_entry(l, struct cg_cgroup_link, cgrp_link_list); + list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) { count += atomic_read(&link->cg->ref.refcount); - l = l->next; } read_unlock(&css_set_lock); return count; @@ -2227,6 +2194,18 @@ static u64 cgroup_read_notify_on_release(struct cgroup *cgrp, return notify_on_release(cgrp); } +static int cgroup_write_notify_on_release(struct cgroup *cgrp, + struct cftype *cft, + u64 val) +{ + clear_bit(CGRP_RELEASABLE, &cgrp->flags); + if (val) + set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); + else + clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); + return 0; +} + /* * for the common functions, 'private' gives the type of file */ @@ -2235,7 +2214,7 @@ static struct cftype files[] = { .name = "tasks", .open = cgroup_tasks_open, .read = cgroup_tasks_read, - .write = cgroup_common_file_write, + .write_u64 = cgroup_tasks_write, .release = cgroup_tasks_release, .private = FILE_TASKLIST, }, @@ -2243,15 +2222,16 @@ static struct cftype files[] = { { .name = "notify_on_release", .read_u64 = cgroup_read_notify_on_release, - .write = cgroup_common_file_write, + .write_u64 = cgroup_write_notify_on_release, .private = FILE_NOTIFY_ON_RELEASE, }, }; static struct cftype cft_release_agent = { .name = "release_agent", - .read = cgroup_common_file_read, - .write = cgroup_common_file_write, + .read_seq_string = cgroup_release_agent_show, + .write_string = cgroup_release_agent_write, + .max_write_len = PATH_MAX, .private = FILE_RELEASE_AGENT, }; @@ -2869,16 +2849,17 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks) * cgroup_clone - clone the cgroup the given subsystem is attached to * @tsk: the task to be moved * @subsys: the given subsystem + * @nodename: the name for the new cgroup * * Duplicate the current cgroup in the hierarchy that the given * subsystem is attached to, and move this task into the new * child. */ -int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys) +int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys, + char *nodename) { struct dentry *dentry; int ret = 0; - char nodename[MAX_CGROUP_TYPE_NAMELEN]; struct cgroup *parent, *child; struct inode *inode; struct css_set *cg; @@ -2903,8 +2884,6 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys) cg = tsk->cgroups; parent = task_cgroup(tsk, subsys->subsys_id); - snprintf(nodename, MAX_CGROUP_TYPE_NAMELEN, "%d", tsk->pid); - /* Pin the hierarchy */ atomic_inc(&parent->root->sb->s_active); @@ -3078,27 +3057,24 @@ static void cgroup_release_agent(struct work_struct *work) while (!list_empty(&release_list)) { char *argv[3], *envp[3]; int i; - char *pathbuf; + char *pathbuf = NULL, *agentbuf = NULL; struct cgroup *cgrp = list_entry(release_list.next, struct cgroup, release_list); list_del_init(&cgrp->release_list); spin_unlock(&release_list_lock); pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); - if (!pathbuf) { - spin_lock(&release_list_lock); - continue; - } - - if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) { - kfree(pathbuf); - spin_lock(&release_list_lock); - continue; - } + if (!pathbuf) + goto continue_free; + if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) + goto continue_free; + agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); + if (!agentbuf) + goto continue_free; i = 0; - argv[i++] = cgrp->root->release_agent_path; - argv[i++] = (char *)pathbuf; + argv[i++] = agentbuf; + argv[i++] = pathbuf; argv[i] = NULL; i = 0; @@ -3112,8 +3088,10 @@ static void cgroup_release_agent(struct work_struct *work) * be a slow process */ mutex_unlock(&cgroup_mutex); call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); - kfree(pathbuf); mutex_lock(&cgroup_mutex); + continue_free: + kfree(pathbuf); + kfree(agentbuf); spin_lock(&release_list_lock); } spin_unlock(&release_list_lock);