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From:   ebiederm@xmission.com (Eric W. Biederman)
To:     <linux-kernel@vger.kernel.org>
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Date:   Fri, 28 Feb 2020 14:18:14 -0600
In-Reply-To: <878skmsbyy.fsf_-_@x220.int.ebiederm.org> (Eric W. Biederman's
        message of "Fri, 28 Feb 2020 14:17:41 -0600")
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Subject: [PATCH 1/3] uml: Don't consult current to find the proc_mnt in mconsole_proc
Sender: linux-kernel-owner@vger.kernel.org
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Inspection of the control flow reveals that mconsole_proc is either
called from mconsole_stop called from mc_work_proc or from
mc_work_proc directly.  The function mc_work_proc is dispatched to a
kernel thread with schedule_work.

All of the threads that run dispatched by schedule_work are in the
init pid namespace.

So make the code clearer and by using init_pid_ns instead of
task_active_pid_ns(current).

Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/um/drivers/mconsole_kern.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index b80a1d616e4e..e8f5c81c2c6c 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -123,7 +123,7 @@ void mconsole_log(struct mc_request *req)
 
 void mconsole_proc(struct mc_request *req)
 {
-	struct vfsmount *mnt = task_active_pid_ns(current)->proc_mnt;
+	struct vfsmount *mnt = init_pid_ns.proc_mnt;
 	char *buf;
 	int len;
 	struct file *file;
-- 
2.25.0