[PATCH v8 2/4] pid: move pidfd_get_pid() to pid.c

[Minchan Kim <minchan@kernel.org>]

process_madvise syscall needs pidfd_get_pid function to translate pidfd to
pid so this patch move the function to kernel/pid.c.

Link: http://lkml.kernel.org/r/20200302193630.68771-5-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Suggested-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jann Horn <jannh@google.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Daniel Colascione <dancol@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Dias <joaodias@google.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oleksandr Natalenko <oleksandr@redhat.com>
Cc: Sandeep Patil <sspatil@google.com>
Cc: SeongJae Park <sj38.park@gmail.com>
Cc: SeongJae Park <sjpark@amazon.de>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Sonny Rao <sonnyrao@google.com>
Cc: Tim Murray <timmurray@google.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: <linux-man@vger.kernel.org>
---
 include/linux/pid.h |  1 +
 kernel/exit.c       | 17 -----------------
 kernel/pid.c        | 17 +++++++++++++++++
 3 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/include/linux/pid.h b/include/linux/pid.h
index 176d6cf80e7c..86e0e7cb7872 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -77,6 +77,7 @@ extern const struct file_operations pidfd_fops;
 struct file;
 
 extern struct pid *pidfd_pid(const struct file *file);
+struct pid *pidfd_get_pid(unsigned int fd);
 
 static inline struct pid *get_pid(struct pid *pid)
 {
diff --git a/kernel/exit.c b/kernel/exit.c
index 00d77e5ba700..8acb702e8241 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1475,23 +1475,6 @@ static long do_wait(struct wait_opts *wo)
 	return retval;
 }
 
-static struct pid *pidfd_get_pid(unsigned int fd)
-{
-	struct fd f;
-	struct pid *pid;
-
-	f = fdget(fd);
-	if (!f.file)
-		return ERR_PTR(-EBADF);
-
-	pid = pidfd_pid(f.file);
-	if (!IS_ERR(pid))
-		get_pid(pid);
-
-	fdput(f);
-	return pid;
-}
-
 static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
 			  int options, struct rusage *ru)
 {
diff --git a/kernel/pid.c b/kernel/pid.c
index f1496b757162..3122043fe364 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -518,6 +518,23 @@ struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
 	return idr_get_next(&ns->idr, &nr);
 }
 
+struct pid *pidfd_get_pid(unsigned int fd)
+{
+	struct fd f;
+	struct pid *pid;
+
+	f = fdget(fd);
+	if (!f.file)
+		return ERR_PTR(-EBADF);
+
+	pid = pidfd_pid(f.file);
+	if (!IS_ERR(pid))
+		get_pid(pid);
+
+	fdput(f);
+	return pid;
+}
+
 /**
  * pidfd_create() - Create a new pid file descriptor.
  *
-- 
2.27.0.111.gc72c7da667-goog