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proc: task_state: ptrace_parent() doesn't need pid_alive() check

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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>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Cc: Sterling Alexander <stalexan@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roland McGrath <roland@hack.frob.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2014-12-10 15:45:18 -08:00 committed by Linus Torvalds
parent b0fafc1111
commit abdba6e9ea
1 changed files with 6 additions and 7 deletions
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9
fs/proc/array.c
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@ -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 user_namespace *user_ns = seq_user_ns(m);
struct group_info *group_info; struct group_info *group_info;
int g; int g;
struct task_struct *tracer;
const struct cred *cred; const struct cred *cred;
pid_t ppid, tpid, tgid, ngid; pid_t ppid, tpid = 0, tgid, ngid;
unsigned int max_fds = 0; unsigned int max_fds = 0;
rcu_read_lock(); rcu_read_lock();
ppid = pid_alive(p) ? ppid = pid_alive(p) ?
task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0; task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
tpid = 0;
if (pid_alive(p)) { tracer = ptrace_parent(p);
struct task_struct *tracer = ptrace_parent(p);
if (tracer) if (tracer)
tpid = task_pid_nr_ns(tracer, ns); tpid = task_pid_nr_ns(tracer, ns);
}
tgid = task_tgid_nr_ns(p, ns); tgid = task_tgid_nr_ns(p, ns);
ngid = task_numa_group_id(p); ngid = task_numa_group_id(p);