From: Christian Brauner <christian.brauner@ubuntu.com>
Date: Thu, 17 Oct 2019 10:18:32 +0000 (+0200)
Subject: pid: use pid_has_task() in pidfd_open()
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=1e1d0f0b1a3e3533ea4cd4021eb251e53827c70b;p=openwrt%2Fstaging%2Fblogic.git

pid: use pid_has_task() in pidfd_open()

Use the new pid_has_task() helper in pidfd_open(). This simplifies the
code and avoids taking rcu_read_{lock,unlock}() and leads to overall
nicer code.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20191017101832.5985-5-christian.brauner@ubuntu.com
---

diff --git a/kernel/pid.c b/kernel/pid.c
index 124d40b239b1..7b5f6c963d72 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -497,7 +497,7 @@ static int pidfd_create(struct pid *pid)
  */
 SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags)
 {
-	int fd, ret;
+	int fd;
 	struct pid *p;
 
 	if (flags)
@@ -510,13 +510,11 @@ SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags)
 	if (!p)
 		return -ESRCH;
 
-	ret = 0;
-	rcu_read_lock();
-	if (!pid_task(p, PIDTYPE_TGID))
-		ret = -EINVAL;
-	rcu_read_unlock();
+	if (pid_has_task(p, PIDTYPE_TGID))
+		fd = pidfd_create(p);
+	else
+		fd = -EINVAL;
 
-	fd = ret ?: pidfd_create(p);
 	put_pid(p);
 	return fd;
 }