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 code related to PID namespace,
this patch reworks on iterative macros;for_each_process and do_each_thread.
This patch can also reduce latency time on process list lookup inside the
container, as we walk along pidmap, instead of every process in system.
Signed-off-by: Gowrishankar M <gowrishanka...@in.ibm.com>
---
include/linux/sched.h | 8 +++++---
kernel/pid.c | 17 +++++++++++++++++
2 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 2e46189..8d3b520 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1917,17 +1917,19 @@ static inline unsigned long wait_task_inactive(struct
task_struct *p,
}
#endif
-#define next_task(p) list_entry(rcu_dereference((p)->tasks.next), struct
task_struct, tasks)
+#include <linux/nsproxy.h>
+#define next_task(p) pid_task(find_ge_tgid(task_pid_vnr(p) + 1,
p->nsproxy->pid_ns), PIDTYPE_PID)
+#define ns_init_task (current->nsproxy->pid_ns == &init_pid_ns ?
next_task((&init_task)) : find_task_by_vpid(1))
#define for_each_process(p) \
- for (p = &init_task ; (p = next_task(p)) != &init_task ; )
+ for (p = ns_init_task ; p != NULL ; p = next_task(p))
/*
* Careful: do_each_thread/while_each_thread is a double loop so
* 'break' will not work as expected - use goto instead.
*/
#define do_each_thread(g, t) \
- for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do
+ for (g = t = ns_init_task ; g != NULL ; (g = t = next_task(g))) 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..3273a96 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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