[PATCH v5 4/7] pid: export pidfd_get_pid

From: Minchan Kim
Date: Fri Feb 14 2020 - 12:06:28 EST


process_madvise syscall needs pidfd_get_pid function to translate
pidfd to pid so this patch exports the function.

Cc: Christian Brauner <christian@xxxxxxxxxx>
Suggested-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Reviewed-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
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 998ae7d24450..023d9c3a8edc 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -75,6 +75,7 @@ extern const struct file_operations pidfd_fops;
struct file;

extern struct pid *pidfd_pid(const struct file *file);
+extern 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 0b81b26a872a..43375f9d8bbc 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1470,23 +1470,6 @@ 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 0f4ecb57214c..360ba480a2a9 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -496,6 +496,23 @@ 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.
*
--
2.25.0.265.gbab2e86ba0-goog