From: Gowrishankar M <gomut...@linux.vnet.ibm.com>
Below patch addresses a common solution for any place where a process
should be checked if it is associated to caller namespace. At present,
we use 'task_pid_vnr(t) > 0' to further proceed with task 't' in current
namespace.
To avoid applying this check in every userspace code related to PID namespace,
this patch provides two new iterative macros;for_each_process_in_ns and
do_each_thread_in_ns.
Signed-off-by: Gowrishankar M <gowrishanka...@linux.vnet.ibm.com>
---
include/linux/pid.h | 1 +
include/linux/sched.h | 12 ++++++++++++
kernel/pid.c | 17 +++++++++++++++++
3 files changed, 30 insertions(+), 0 deletions(-)
diff --git a/include/linux/pid.h b/include/linux/pid.h
index d7e98ff..1c6b24f 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -117,6 +117,7 @@ extern struct pid *find_vpid(int nr);
*/
extern struct pid *find_get_pid(int nr);
extern struct pid *find_ge_pid(int nr, struct pid_namespace *);
+extern struct pid *find_ge_tgid(int nr, struct pid_namespace *);
int next_pidmap(struct pid_namespace *pid_ns, int last);
extern struct pid *alloc_pid(struct pid_namespace *ns);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 2e46189..bdd9f0d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1919,16 +1919,28 @@ static inline unsigned long wait_task_inactive(struct
task_struct *p,
#define next_task(p) list_entry(rcu_dereference((p)->tasks.next), struct
task_struct, tasks)
+#define next_task_in_ns(p, ns) \
+ pid_task(find_ge_tgid(task_pid_nr_ns(p, ns) + 1, ns), PIDTYPE_PID)
+
#define for_each_process(p) \
for (p = &init_task ; (p = next_task(p)) != &init_task ; )
+#define for_each_process_in_ns(p, ns) \
+ for (p = find_task_by_pid_ns(1, ns) ; p != NULL ; \
+ p = next_task_in_ns(p, ns))
+
/*
* Careful: do_each_thread/while_each_thread is a double loop so
* 'break' will not work as expected - use goto instead.
+ * same applies to do_each_thread_in_ns.
*/
#define do_each_thread(g, t) \
for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do
+#define do_each_thread_in_ns(g, t, ns) \
+ for (g = t = find_task_by_pid_ns(1, ns) ; g != NULL ; \
+ (g = t = next_task_in_ns(g, ns))) do
+
#define while_each_thread(g, t) \
while ((t = next_thread(t)) != g)
diff --git a/kernel/pid.c b/kernel/pid.c
index 064e76a..15f707a 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -493,6 +493,23 @@ struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
return pid;
}
+struct pid *find_ge_tgid(int nr, struct pid_namespace *ns)
+{
+ struct pid *pid;
+ struct task_struct *task;
+
+retry:
+ pid = find_ge_pid(nr, ns);
+ if (pid) {
+ task = pid_task(pid, PIDTYPE_PID);
+ if (!task || !has_group_leader_pid(task)) {
+ nr += 1;
+ goto retry;
+ }
+ }
+ return pid;
+}
+
/*
* The pid hash table is scaled according to the amount of memory in the
* machine. From a minimum of 16 slots up to 4096 slots at one gigabyte or
--
1.5.5.1
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