This patch helps creating a pid mapping data to parent processes. Reading 'NSpid' field in '/proc/$PID/status' is currently a simple way to getting child pid from parent pid in userspace. But this field supplies only single direction mapping('parent pid' to 'child pid'). If parent process want to translate child pid to current namespace pid, there is no way to get except full searching in current procfs.
This patch will helps in getting current namespace pid by reading child procfs file without any side effects. For example, Process id is 24771 in level 0, 435 in level 1. a) The output of '/proc/24771/status' in level 0 namespace. NSpid : 24771 435 b) The output of '/proc/435/status' in level 1 namespace. NSpid : 435 c) Process in level 0 mount level1 proc to '/var/child/proc' after setns(). The output of '/var/child/proc/435/status' is NSpid : 24771 435 Signed-off-by: Kuenhwan Kwak <kh243.k...@samsung.com> --- fs/proc/array.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/proc/array.c b/fs/proc/array.c index 3f57dac..b3f5efa 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -83,6 +83,7 @@ #include <linux/tracehook.h> #include <linux/string_helpers.h> #include <linux/user_namespace.h> +#include <linux/sched.h> #include <asm/pgtable.h> #include <asm/processor.h> @@ -149,6 +150,9 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, const struct cred *cred; pid_t ppid, tpid = 0, tgid, ngid; unsigned int max_fds = 0; +#ifdef CONFIG_PID_NS + struct pid_namespace *current_pid_ns = task_active_pid_ns(current); +#endif rcu_read_lock(); ppid = pid_alive(p) ? @@ -198,19 +202,19 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, #ifdef CONFIG_PID_NS seq_puts(m, "\nNStgid:"); - for (g = ns->level; g <= pid->level; g++) + for (g = current_pid_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++) + for (g = current_pid_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++) + for (g = current_pid_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++) + for (g = current_pid_ns->level; g <= pid->level; g++) seq_printf(m, "\t%d", task_session_nr_ns(p, pid->numbers[g].ns)); #endif -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/