Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754315AbaKEKmE (ORCPT ); Wed, 5 Nov 2014 05:42:04 -0500 Received: from cn.fujitsu.com ([59.151.112.132]:52597 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753644AbaKEKmA convert rfc822-to-8bit (ORCPT ); Wed, 5 Nov 2014 05:42:00 -0500 X-IronPort-AV: E=Sophos;i="5.04,848,1406563200"; d="scan'208";a="42891630" From: Chen Hanxiao To: "Eric W. Biederman" , Serge Hallyn , Oleg Nesterov CC: , , David Howells , Richard Weinberger , Pavel Emelyanov , Vasiliy Kulikov , Mateusz Guzik Subject: [PATCH 1/2v6] procfs: show hierarchy of pid namespace Date: Wed, 5 Nov 2014 18:41:54 +0800 Message-ID: <1415184115-12022-2-git-send-email-chenhanxiao@cn.fujitsu.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1415184115-12022-1-git-send-email-chenhanxiao@cn.fujitsu.com> References: <1415184115-12022-1-git-send-email-chenhanxiao@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Originating-IP: [10.167.226.237] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We lack of pid hierarchy information, and this will lead to: a) we don't know pids' relationship, who is whose child: /proc/PID/ns/pid only tell us whether two pids live in different ns b) bring trouble to nested lxc container check/restore/migration c) bring trouble to pid translation between containers; This patch will show the hierarchy of pid namespace by pidns_hierarchy like: [root@localhost ~]#cat /proc/pidns_hierarchy 18060 18102 1534 18060 18102 1600 1550 *Note: numbers represent the pid 1 in different ns It shows the pid hierarchy below: init_pid_ns (not showed in /proc/pidns_hierarchy) │ ┌────────────┐ ns1 ns2 │ │ 1550 18060 │ │ ns3 │ 18102 │ ┌──────────┐ ns4 ns5 │ │ 1534 1600 Every pid printed in pidns_hierarchy is the init pid of that pid ns level. Signed-off-by: Chen Hanxiao --- v6: fix get_pid leaks and do some cleanups; v5: collect pid by find_ge_pid; use local list inside nslist_proc_show; use get_pid, remove mutex lock. v4: simplify pid collection and some performance optimizamtion fix another race issue. v3: fix a race issue and memory leak issue v2: use a procfs text file instead of dirs under /proc fs/proc/Kconfig | 6 ++ fs/proc/Makefile | 1 + fs/proc/pidns_hierarchy.c | 227 ++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 234 insertions(+) create mode 100644 fs/proc/pidns_hierarchy.c diff --git a/fs/proc/Kconfig b/fs/proc/Kconfig index 2183fcf..4bb111c 100644 --- a/fs/proc/Kconfig +++ b/fs/proc/Kconfig @@ -71,3 +71,9 @@ config PROC_PAGE_MONITOR /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap, /proc/kpagecount, and /proc/kpageflags. Disabling these interfaces will reduce the size of the kernel by approximately 4kb. + +config PROC_PID_HIERARCHY + bool "Enable /proc/pidns_hierarchy support" if EXPERT + depends on PROC_FS + help + Show pid namespace hierarchy information diff --git a/fs/proc/Makefile b/fs/proc/Makefile index 7151ea4..33e384b 100644 --- a/fs/proc/Makefile +++ b/fs/proc/Makefile @@ -30,3 +30,4 @@ proc-$(CONFIG_PROC_KCORE) += kcore.o proc-$(CONFIG_PROC_VMCORE) += vmcore.o proc-$(CONFIG_PRINTK) += kmsg.o proc-$(CONFIG_PROC_PAGE_MONITOR) += page.o +proc-$(CONFIG_PROC_PID_HIERARCHY) += pidns_hierarchy.o diff --git a/fs/proc/pidns_hierarchy.c b/fs/proc/pidns_hierarchy.c new file mode 100644 index 0000000..aee359f --- /dev/null +++ b/fs/proc/pidns_hierarchy.c @@ -0,0 +1,227 @@ +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * /proc/pidns_hierarchy + * + * show the hierarchy of pid namespace + */ + +#define NS_HIERARCHY "pidns_hierarchy" + +/* list for host pid collection */ +struct pidns_list { + struct list_head list; + struct pid *pid; +}; + +static void free_pidns_list(struct list_head *head) +{ + struct pidns_list *tmp, *pos; + + list_for_each_entry_safe(pos, tmp, head, list) { + list_del(&pos->list); + put_pid(pos->pid); + kfree(pos); + } +} + +static int +pidns_list_add(struct pid *pid, struct list_head *list_head) +{ + struct pidns_list *ent; + + ent = kmalloc(sizeof(*ent), GFP_KERNEL); + if (!ent) + return -ENOMEM; + + ent->pid = pid; + list_add_tail(&ent->list, list_head); + + return 0; +} + +static int +pidns_list_filter(struct list_head *pidns_pid_list, + struct list_head *pidns_pid_tree) +{ + struct pidns_list *pos, *pos_t; + struct pid_namespace *ns0, *ns1; + struct pid *pid0, *pid1; + int rc, flag = 0; + + /* + * screen pids with relationship + * in pidns_pid_list, we may add pids like: + * ns0 ns1 ns2 + * pid1->pid2->pid3 + * we should screen pid1, pid2 and keep pid3 + */ + list_for_each_entry(pos, pidns_pid_list, list) { + list_for_each_entry(pos_t, pidns_pid_list, list) { + flag = 0; + pid0 = pos->pid; + pid1 = pos_t->pid; + ns0 = pid0->numbers[pid0->level].ns; + ns1 = pid1->numbers[pid1->level].ns; + if (pos->pid->level < pos_t->pid->level) + for (; ns1 != NULL; ns1 = ns1->parent) + if (ns0 == ns1) { + flag = 1; + break; + } + /* a redundant pid found */ + if (flag == 1) + break; + } + + if (flag == 0) { + rcu_read_lock(); + get_pid(pos->pid); + rcu_read_unlock(); + rc = pidns_list_add(pos->pid, pidns_pid_tree); + if (rc) { + put_pid(pos->pid); + goto out; + } + } + } + + /* + * Now all usefull stuffs are in pidns_pid_tree, + * free pidns_pid_list + */ + free_pidns_list(pidns_pid_list); + + return 0; + +out: + free_pidns_list(pidns_pid_tree); + return rc; +} + +/* + * collect pids and stored in pidns_pid_list, + * then remove duplicated ones, + * add the rest to pidns_pid_tree + */ +static int proc_pidns_list_refresh(struct pid_namespace *curr_ns, + struct list_head *pidns_pid_list, + struct list_head *pidns_pid_tree) +{ + struct pid *pid; + int new_nr, nr = 0; + int rc; + + /* collect pids in current namespace */ + while (nr < PID_MAX_LIMIT) { + rcu_read_lock(); + pid = find_ge_pid(nr, curr_ns); + if (pid) { + new_nr = pid_vnr(pid); + if (!is_child_reaper(pid)) { + nr = new_nr + 1; + rcu_read_unlock(); + continue; + } + get_pid(pid); + rcu_read_unlock(); + rc = pidns_list_add(pid, pidns_pid_list); + if (rc) { + put_pid(pid); + goto out; + } + } else { + rcu_read_unlock(); + break; + } + nr = new_nr + 1; + } + + /* + * Only one pid found as the child reaper, + * so current pid namespace do not have sub-namespace, + * return 0 directly. + */ + if (list_is_singular(pidns_pid_list)) { + rc = 0; + goto out; + } + + /* + * screen duplicate pids from pidns_pid_list + * and form a new list pidns_pid_tree. + */ + rc = pidns_list_filter(pidns_pid_list, pidns_pid_tree); + if (rc) + goto out; + + return 0; + +out: + free_pidns_list(pidns_pid_list); + return rc; +} + +static int nslist_proc_show(struct seq_file *m, void *v) +{ + struct pidns_list *pos; + struct pid_namespace *ns, *curr_ns; + struct pid *pid; + char pid_buf[16]; + int i, rc; + + LIST_HEAD(pidns_pid_list); + LIST_HEAD(pidns_pid_tree); + + curr_ns = task_active_pid_ns(current); + + rc = proc_pidns_list_refresh(curr_ns, &pidns_pid_list, &pidns_pid_tree); + if (rc) + return rc; + + /* print pid namespace's hierarchy */ + list_for_each_entry(pos, &pidns_pid_tree, list) { + pid = pos->pid; + for (i = curr_ns->level + 1; i <= pid->level; i++) { + ns = pid->numbers[i].ns; + /* show PID '1' in specific pid ns */ + snprintf(pid_buf, 16, "%u", + pid_vnr(find_pid_ns(1, ns))); + seq_printf(m, "%s ", pid_buf); + } + + seq_putc(m, '\n'); + } + + free_pidns_list(&pidns_pid_tree); + + return 0; +} + +static int nslist_proc_open(struct inode *inode, struct file *file) +{ + return single_open(file, nslist_proc_show, NULL); +} + +static const struct file_operations proc_nspid_nslist_fops = { + .open = nslist_proc_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +static int __init pidns_hierarchy_init(void) +{ + proc_create(NS_HIERARCHY, S_IWUGO, + NULL, &proc_nspid_nslist_fops); + + return 0; +} +fs_initcall(pidns_hierarchy_init); -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/