This series will expose pid inside containers
via procfs.
Also show the hierarchy of pid namespcae.
Then we could know how pid looks inside a container
and their ns relationships.
1. helpful for nested container check/restore
>From /proc/PID/ns/pid, we could know whether two pid lived
in the same ns.
>From this patch, we could know whether two pid had relationship
between each other.
2. used for pid translation from container
Ex:
init_pid_ns ns1 ns2
t1 2
t2 `- 3 1
t3 `- 4 3
t4 `- 5 `- 5 1
t5 `- 6 `- 8 3
It could solve problems like: we see a pid 3 goes wrong
in container's log, what is its pid on hosts:
a) inside container:
# readlink /proc/3/ns/pid
pid:[4026532388]
b) on host:
We show it in the form of :
<init_PID> <parent_of_init_PID> <relative PID level>
# cat /proc/pidns_hierarchy
14918 1 1
16263 14918 2
16581 1 1
Then we could easily find /proc/16263/ns/pid->4026532388.
On host, we knew that reported pid 3 is in level 2,
and its parental pid ns is from pid 14918.
c) on host, check child of 16263, grep it from status:
NSpid: 16268 8 3
We knew that pid 16268 is pid 3 reported by container.
v7: change stype to be consistent with current interface like
<init_PID> <parent_of_init_PID> <relative PID level>
remove EXPERT dependent in Kconfig
v6: fix some 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 in pidns_hierarchy;
add another two fielsd: NSpgid and NSsid.
v2: use a procfs text file instead of dirs under /proc for
showing pidns hierarchy;
add two new fields: NStgid and NSpid
keep fields of Tgid and Pid unchanged for back compatibility.
Chen Hanxiao (2):
procfs: show hierarchy of pid namespace
/proc/PID/status: show all sets of pid according to ns
fs/proc/Kconfig | 6 +
fs/proc/Makefile | 1 +
fs/proc/array.c | 17 +++
fs/proc/pidns_hierarchy.c | 280 ++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 304 insertions(+)
create mode 100644 fs/proc/pidns_hierarchy.c
--
1.9.3
If some issues occurred inside a container guest, host user
could not know which process is in trouble just by guest pid:
the users of container guest only knew the pid inside containers.
This will bring obstacle for trouble shooting.
This patch adds four fields: NStgid, NSpid, NSpgid and NSsid:
a) In init_pid_ns, nothing changed;
b) In one pidns, will tell the pid inside containers:
NStgid: 21776 5 1
NSpid: 21776 5 1
NSpgid: 21776 5 1
NSsid: 21729 1 0
** Process id is 21776 in level 0, 5 in level 1, 1 in level 2.
c) If pidns is nested, it depends on which pidns are you in.
NStgid: 5 1
NSpid: 5 1
NSpgid: 5 1
NSsid: 1 0
** Views from level 1
Acked-by: Serge Hallyn <[email protected]>
Tested-by: Serge Hallyn <[email protected]>
Signed-off-by: Chen Hanxiao <[email protected]>
---
No change since v3
v3: add another two fielsd: NSpgid and NSsid.
v2: add two new fields: NStgid and NSpid.
keep fields of Tgid and Pid unchanged for back compatibility.
fs/proc/array.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/fs/proc/array.c b/fs/proc/array.c
index cd3653e..c30875d 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -193,6 +193,23 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
from_kgid_munged(user_ns, cred->egid),
from_kgid_munged(user_ns, cred->sgid),
from_kgid_munged(user_ns, cred->fsgid));
+ seq_puts(m, "NStgid:");
+ for (g = ns->level; g <= pid->level; g++)
+ seq_printf(m, "\t%d ",
+ task_tgid_nr_ns(p, pid->numbers[g].ns));
+ seq_puts(m, "\nNSpid:");
+ for (g = ns->level; g <= pid->level; g++)
+ seq_printf(m, "\t%d ",
+ task_pid_nr_ns(p, pid->numbers[g].ns));
+ seq_puts(m, "\nNSpgid:");
+ for (g = ns->level; g <= pid->level; g++)
+ seq_printf(m, "\t%d ",
+ task_pgrp_nr_ns(p, pid->numbers[g].ns));
+ seq_puts(m, "\nNSsid:");
+ for (g = ns->level; g <= pid->level; g++)
+ seq_printf(m, "\t%d ",
+ task_session_nr_ns(p, pid->numbers[g].ns));
+ seq_putc(m, '\n');
task_lock(p);
if (p->files)
--
1.9.3
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:
<init_PID> <parent_of_init_PID> <relative PID level>
Ex:
[root@localhost ~]#cat /proc/pidns_hierarchy
18060 1 1
18102 18060 2
1534 18102 3
1600 18102 3
1550 1 1
*Note: numbers represent the pid 1 in different ns
It shows the pid hierarchy below:
init_pid_ns 1
│
┌────────────┐
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 <[email protected]>
---
v7: change stype to be consistent with current interface like
<init_PID> <parent_of_init_PID> <relative PID level>
remove EXPERT dependent in Kconfig
v6: fix a get_pid leak 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 | 280 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 287 insertions(+)
create mode 100644 fs/proc/pidns_hierarchy.c
diff --git a/fs/proc/Kconfig b/fs/proc/Kconfig
index 2183fcf..82dda55 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"
+ 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..4629bfd
--- /dev/null
+++ b/fs/proc/pidns_hierarchy.c
@@ -0,0 +1,280 @@
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/proc_fs.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/pid_namespace.h>
+#include <linux/seq_file.h>
+
+/*
+ * /proc/pidns_hierarchy
+ *
+ * show the hierarchy of pid namespace in:
+ * <init_PID> <parent_of_init_PID> <relative PID level>
+ *
+ * init_PID: child reaper in ns
+ * parent_of_init_PID: init_PID's parent, also child reaper
+ * relative PID level: pid level relative to caller's ns
+ */
+
+#define NS_HIERARCHY "pidns_hierarchy"
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+
+/* list for host pid collection */
+struct pidns_list {
+ struct list_head list;
+ struct pid *pid;
+ int show_level;
+};
+
+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,
+ int show_level)
+{
+ struct pidns_list *ent;
+
+ ent = kmalloc(sizeof(*ent), GFP_KERNEL);
+ if (!ent)
+ return -ENOMEM;
+
+ ent->pid = pid;
+ ent->show_level = show_level;
+ 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) {
+ get_pid(pos->pid);
+ rc = pidns_list_add(pos->pid, pidns_pid_tree, 0);
+ if (rc) {
+ put_pid(pos->pid);
+ goto cleanup;
+ }
+ }
+ }
+
+ /*
+ * Now all useful stuffs are in pidns_pid_tree,
+ * free pidns_pid_list
+ */
+ free_pidns_list(pidns_pid_list);
+
+ return 0;
+
+cleanup:
+ free_pidns_list(pidns_pid_tree);
+ return rc;
+}
+
+static void
+pidns_list_set_show_level(struct list_head *pidns_list_in,
+ struct pid_namespace *curr_ns)
+{
+ struct pidns_list *pos, *pos_t;
+ struct pid *pid0, *pid1;
+ int i;
+
+ /*
+ * From the pid hierarchy point of view,
+ * we already had a list of pids who are not
+ * the subset of each other.
+ * But part of them may be same.
+ * We need to set the show_level of each pids:
+ * pid0: A->B->C pid1: A->B->D
+ * show_level 2 0
+ * We use show_level to identify
+ * the public part of each pids.
+ */
+ list_for_each_entry(pos, pidns_list_in, list) {
+ list_for_each_entry(pos_t, pidns_list_in, list) {
+ pid0 = pos->pid;
+ pid1 = pos_t->pid;
+ if (pid0 == pid1)
+ continue;
+ if (pos_t->show_level > 0)
+ continue;
+ for (i = curr_ns->level + 1; i <= pid0->level; i++) {
+ /* skip the public parts */
+ if (pid0->numbers[i].ns ==
+ pid1->numbers[i].ns)
+ continue;
+ else
+ break;
+ }
+ pos->show_level = i - 1;
+ }
+ }
+}
+
+/*
+ * 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) {
+ rcu_read_unlock();
+ break;
+ }
+
+ 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, 0);
+ if (rc) {
+ put_pid(pid);
+ goto cleanup;
+ }
+ 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 cleanup;
+ }
+
+ /*
+ * 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 cleanup;
+
+ return 0;
+
+cleanup:
+ 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], ppid_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;
+
+ pidns_list_set_show_level(&pidns_pid_tree, curr_ns);
+
+ /* print pid namespace's hierarchy */
+ list_for_each_entry(pos, &pidns_pid_tree, list) {
+ pid = pos->pid;
+ for (i = MAX(curr_ns->level, pos->show_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)));
+ ns = pid->numbers[i - 1].ns;
+ snprintf(ppid_buf, 16, "%u",
+ pid_vnr(find_pid_ns(1, ns)));
+ seq_printf(m, "%s\t%s\t%d\n", pid_buf, ppid_buf,
+ i - curr_ns->level);
+ }
+ }
+
+ 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
Am 12.11.2014 um 11:08 schrieb Chen Hanxiao:
> 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:
>
> <init_PID> <parent_of_init_PID> <relative PID level>
>
> Ex:
> [root@localhost ~]#cat /proc/pidns_hierarchy
> 18060 1 1
> 18102 18060 2
> 1534 18102 3
> 1600 18102 3
> 1550 1 1
> *Note: numbers represent the pid 1 in different ns
>
> It shows the pid hierarchy below:
>
> init_pid_ns 1
> │
> ┌────────────┐
> 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 <[email protected]>
> ---
> v7: change stype to be consistent with current interface like
> <init_PID> <parent_of_init_PID> <relative PID level>
> remove EXPERT dependent in Kconfig
> v6: fix a get_pid leak 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 | 280 ++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 287 insertions(+)
> create mode 100644 fs/proc/pidns_hierarchy.c
>
> diff --git a/fs/proc/Kconfig b/fs/proc/Kconfig
> index 2183fcf..82dda55 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"
> + 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..4629bfd
> --- /dev/null
> +++ b/fs/proc/pidns_hierarchy.c
> @@ -0,0 +1,280 @@
> +#include <linux/init.h>
> +#include <linux/errno.h>
> +#include <linux/proc_fs.h>
> +#include <linux/module.h>
> +#include <linux/list.h>
> +#include <linux/slab.h>
> +#include <linux/pid_namespace.h>
> +#include <linux/seq_file.h>
> +
> +/*
> + * /proc/pidns_hierarchy
> + *
> + * show the hierarchy of pid namespace in:
> + * <init_PID> <parent_of_init_PID> <relative PID level>
> + *
> + * init_PID: child reaper in ns
> + * parent_of_init_PID: init_PID's parent, also child reaper
> + * relative PID level: pid level relative to caller's ns
> + */
> +
> +#define NS_HIERARCHY "pidns_hierarchy"
> +#define MAX(a, b) ((a) > (b) ? (a) : (b))
Please use max() from kernel.h, there is no need to reinvent the wheel.
> +
> +/* list for host pid collection */
> +struct pidns_list {
> + struct list_head list;
> + struct pid *pid;
> + int show_level;
s/show_level/level, to keep it easy. :-)
> +};
> +
> +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,
> + int show_level)
> +{
> + struct pidns_list *ent;
> +
> + ent = kmalloc(sizeof(*ent), GFP_KERNEL);
> + if (!ent)
> + return -ENOMEM;
> +
> + ent->pid = pid;
> + ent->show_level = show_level;
> + 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) {
> + get_pid(pos->pid);
> + rc = pidns_list_add(pos->pid, pidns_pid_tree, 0);
> + if (rc) {
> + put_pid(pos->pid);
> + goto cleanup;
> + }
> + }
> + }
> +
> + /*
> + * Now all useful stuffs are in pidns_pid_tree,
> + * free pidns_pid_list
> + */
> + free_pidns_list(pidns_pid_list);
> +
> + return 0;
> +
> +cleanup:
> + free_pidns_list(pidns_pid_tree);
> + return rc;
> +}
> +
> +static void
> +pidns_list_set_show_level(struct list_head *pidns_list_in,
> + struct pid_namespace *curr_ns)
> +{
> + struct pidns_list *pos, *pos_t;
> + struct pid *pid0, *pid1;
> + int i;
> +
> + /*
> + * From the pid hierarchy point of view,
> + * we already had a list of pids who are not
> + * the subset of each other.
> + * But part of them may be same.
> + * We need to set the show_level of each pids:
> + * pid0: A->B->C pid1: A->B->D
> + * show_level 2 0
> + * We use show_level to identify
> + * the public part of each pids.
> + */
> + list_for_each_entry(pos, pidns_list_in, list) {
> + list_for_each_entry(pos_t, pidns_list_in, list) {
> + pid0 = pos->pid;
> + pid1 = pos_t->pid;
> + if (pid0 == pid1)
> + continue;
> + if (pos_t->show_level > 0)
> + continue;
> + for (i = curr_ns->level + 1; i <= pid0->level; i++) {
> + /* skip the public parts */
> + if (pid0->numbers[i].ns ==
> + pid1->numbers[i].ns)
> + continue;
> + else
> + break;
> + }
> + pos->show_level = i - 1;
> + }
> + }
> +}
> +
> +/*
> + * collect pids and stored in pidns_pid_list,
s/stored/store
> + * then remove duplicated ones,
> + * add the rest to pidns_pid_tree
> + */
This comment is a bit confusing.
What about "proc_pidns_list_refresh - Finds all init pids, places them into pidns_pid_list
and then stores the hirarchy into pidns_pid_tree."?
Beside of my minor comments I like the patch. :-)
Thanks a lot for doing this work!
Thanks,
//richard
> -----Original Message-----
> From: Richard Weinberger [mailto:[email protected]]
> Sent: Wednesday, November 12, 2014 7:15 PM
> To: Chen, Hanxiao/陈 晗霄; Eric W. Biederman; Serge Hallyn; Oleg Nesterov
> Cc: [email protected]; [email protected]; David
> Howells; Richard Weinberger; Pavel Emelyanov; Vasiliy Kulikov; Mateusz Guzik
> Subject: Re: [PATCH v7 1/2] procfs: show hierarchy of pid namespace
>
> Am 12.11.2014 um 11:08 schrieb Chen Hanxiao:
> > 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:
> >
> > <init_PID> <parent_of_init_PID> <relative PID level>
> >
> > Ex:
> > [root@localhost ~]#cat /proc/pidns_hierarchy
> > 18060 1 1
> > 18102 18060 2
> > 1534 18102 3
> > 1600 18102 3
> > 1550 1 1
> > *Note: numbers represent the pid 1 in different ns
> >
[snip]
> > +
> > +#define NS_HIERARCHY "pidns_hierarchy"
> > +#define MAX(a, b) ((a) > (b) ? (a) : (b))
>
> Please use max() from kernel.h, there is no need to reinvent the wheel.
>
Thanks for your reminding.
> > +
> > +/* list for host pid collection */
> > +struct pidns_list {
> > + struct list_head list;
> > + struct pid *pid;
> > + int show_level;
>
> s/show_level/level, to keep it easy. :-)
Sure, also change the type to unsigned int
for making max() happy.
[snip]
> > +}
> > +
> > +/*
> > + * collect pids and stored in pidns_pid_list,
>
> s/stored/store
Oops...
>
> > + * then remove duplicated ones,
> > + * add the rest to pidns_pid_tree
> > + */
>
> This comment is a bit confusing.
>
> What about "proc_pidns_list_refresh - Finds all init pids, places them into
> pidns_pid_list
> and then stores the hirarchy into pidns_pid_tree."?
>
That's much more clear.
> Beside of my minor comments I like the patch. :-)
> Thanks a lot for doing this work!
>
Thanks for your kindly help. :)
- Chen
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