linux-kernel - [PATCH] kernel/hung_task.c: make type annotations consistent

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Date:   Wed, 28 Oct 2020 14:05:41 +0100
From:   Lukas Bulwahn <lukas.bulwahn@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Hellwig <hch@....de>
Cc:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Andrey Ignatov <rdna@...com>,
        Al Viro <viro@...iv.linux.org.uk>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-safety@...ts.elisa.tech,
        Lukas Bulwahn <lukas.bulwahn@...il.com>
Subject: [PATCH] kernel/hung_task.c: make type annotations consistent

Commit 32927393dc1c ("sysctl: pass kernel pointers to ->proc_handler")
removed various __user annotations from function signatures as part of its
refactoring.

It also removed the __user annotation for proc_dohung_task_timeout_secs()
at its declaration in ./sched/sysctl.h, but not at its definition in
./kernel/hung_task.c.

Hence, sparse complains:

  kernel/hung_task.c:271:5: error: \
  symbol 'proc_dohung_task_timeout_secs' redeclared with different type \
  (incompatible argument 3 (different address spaces))

Adjust the annotation at the definition fitting to that refactoring to make
sparse happy again, which also resolves this warning from sparse:

  kernel/hung_task.c:277:52: warning: incorrect type in argument 3 \
    (different address spaces)
  kernel/hung_task.c:277:52:    expected void *
  kernel/hung_task.c:277:52:    got void [noderef] __user *buffer

No functional change. No change in object code.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
---
applies cleanly on current master and next-20201028

Christoph, can I get quick ack from you on a fix to your refactoring?
Andrew, please pick this minor non-urgent clean-up patch.

 kernel/hung_task.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index a672db830a94..bb2e3e15c84c 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -269,8 +269,7 @@ static long hung_timeout_jiffies(unsigned long last_checked,
  * Process updating of timeout sysctl
  */
 int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
-				  void __user *buffer,
-				  size_t *lenp, loff_t *ppos)
+				  void *buffer, size_t *lenp, loff_t *ppos)
 {
 	int ret;
 
-- 
2.17.1