[patch 25/40] pid: move pidfd_get_pid() to pid.c

[Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>]

From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: pid: move pidfd_get_pid() to pid.c

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@xxxxxxxxxx
Link: http://lkml.kernel.org/r/20200622192900.22757-3-minchan@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20200901000633.1920247-3-minchan@xxxxxxxxxx
Reviewed-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Suggested-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Reviewed-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Acked-by: Christian Brauner <christian.brauner@xxxxxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Brian Geffon <bgeffon@xxxxxxxxxx>
Cc: Daniel Colascione <dancol@xxxxxxxxxx>
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: John Dias <joaodias@xxxxxxxxxx>
Cc: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Oleksandr Natalenko <oleksandr@xxxxxxxxxx>
Cc: Sandeep Patil <sspatil@xxxxxxxxxx>
Cc: SeongJae Park <sj38.park@xxxxxxxxx>
Cc: SeongJae Park <sjpark@xxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Sonny Rao <sonnyrao@xxxxxxxxxx>
Cc: Tim Murray <timmurray@xxxxxxxxxx>
Cc: Christian Brauner <christian.brauner@xxxxxxxxxx>
Cc: Florian Weimer <fw@xxxxxxxxxxxxx>
Cc: <linux-man@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 include/linux/pid.h |    1 +
 kernel/exit.c       |   19 -------------------
 kernel/pid.c        |   19 +++++++++++++++++++
 3 files changed, 20 insertions(+), 19 deletions(-)

--- a/include/linux/pid.h~pid-move-pidfd_get_pid-to-pidc
+++ a/include/linux/pid.h
@@ -77,6 +77,7 @@ extern const struct file_operations pidf
 struct file;
 
 extern struct pid *pidfd_pid(const struct file *file);
+struct pid *pidfd_get_pid(unsigned int fd, unsigned int *flags);
 
 static inline struct pid *get_pid(struct pid *pid)
 {
--- a/kernel/exit.c~pid-move-pidfd_get_pid-to-pidc
+++ a/kernel/exit.c
@@ -1474,25 +1474,6 @@ end:
 	return retval;
 }
 
-static struct pid *pidfd_get_pid(unsigned int fd, unsigned int *flags)
-{
-	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);
-		*flags = f.file->f_flags;
-	}
-
-	fdput(f);
-	return pid;
-}
-
 static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
 			  int options, struct rusage *ru)
 {
--- a/kernel/pid.c~pid-move-pidfd_get_pid-to-pidc
+++ a/kernel/pid.c
@@ -520,6 +520,25 @@ struct pid *find_ge_pid(int nr, struct p
 	return idr_get_next(&ns->idr, &nr);
 }
 
+struct pid *pidfd_get_pid(unsigned int fd, unsigned int *flags)
+{
+	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);
+		*flags = f.file->f_flags;
+	}
+
+	fdput(f);
+	return pid;
+}
+
 /**
  * pidfd_create() - Create a new pid file descriptor.
  *
_