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Subject[PATCH 4/4] proc: task_state: ptrace_parent() doesn't need pid_alive() check
p->ptrace != 0 means that release_task(p) was not called, so pid_alive()
buys nothing and we can remove this check. Other callers already use it
directly without additional checks.

Note: with or without this patch ptrace_parent() can return the pointer
to the freed task, this will be explained/fixed later.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
fs/proc/array.c | 13 ++++++-------
1 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 800e30f..bd117d0 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -157,19 +157,18 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
struct user_namespace *user_ns = seq_user_ns(m);
struct group_info *group_info;
int g;
+ struct task_struct *tracer;
const struct cred *cred;
- pid_t ppid, tpid, tgid, ngid;
+ pid_t ppid, tpid = 0, tgid, ngid;
unsigned int max_fds = 0;

rcu_read_lock();
ppid = pid_alive(p) ?
task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
- tpid = 0;
- if (pid_alive(p)) {
- struct task_struct *tracer = ptrace_parent(p);
- if (tracer)
- tpid = task_pid_nr_ns(tracer, ns);
- }
+
+ tracer = ptrace_parent(p);
+ if (tracer)
+ tpid = task_pid_nr_ns(tracer, ns);

tgid = task_tgid_nr_ns(p, ns);
ngid = task_numa_group_id(p);
--
1.5.5.1


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