linux-kernel - [PATCH] mei: mei-amt-version: remove unneeded call of mei

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Date:	Fri, 03 Jan 2014 18:10:34 +0100
From:	Paul Bolle <pebolle@...cali.nl>
To:	David Howells <dhowells@...hat.com>
Cc:	akpm@...ux-foundation.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Tomas Winkler <tomas.winkler@...el.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] mei: mei-amt-version: remove unneeded call of mei_deinit()

On Fri, 2014-01-03 at 16:34 +0000, David Howells wrote:
> Paul Bolle <pebolle@...cali.nl> wrote:
> > But it turns out that call of mei_deinit() isn't needed at all. All of
> > the members of mei_cl will be set later in mei_init() and none will be
> > used before they are set. So we can simply drop this call of
> > mei_deinit()."
> > 
> > Is that analysis (still) correct?
> 
> It looks true as the code stands.  Can you send me your patch?

Sure. Below the scissors (hope I've typed those correctly).


Paul Bolle
-------->8------- 
From: Paul Bolle <pebolle@...cali.nl>

Building mei-amt-version.o triggers a GCC warning:
    Documentation/misc-devices/mei/mei-amt-version.c: In function 'main':
    Documentation/misc-devices/mei/mei-amt-version.c:103:5: warning: 'acmd.fd' is used uninitialized in this function [-Wuninitialized]
      if (cl->fd != -1)
         ^
    Documentation/misc-devices/mei/mei-amt-version.c:443:21: note: 'acmd.fd' was declared here
      struct amt_host_if acmd;
                         ^

GCC is correct. See, the call chain that GCC detects must be
    main()
        amt_host_if_init()
            mei_init()
                mei_deinit()

But when we enter mei_deinit() struct amt_host_if acmd is still
unitialized. That makes the test for (effectively) amt_host_if->mei_cl->fd
bogus.

But it turns out that call of mei_deinit() isn't needed at all. All of
the members of mei_cl will be set later in mei_init() and none will be
used before they are set. So we can simply drop this call of
mei_deinit().

Signed-off-by: Paul Bolle <pebolle@...cali.nl>
---
 Documentation/misc-devices/mei/mei-amt-version.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/Documentation/misc-devices/mei/mei-amt-version.c b/Documentation/misc-devices/mei/mei-amt-version.c
index 49e4f77..57d0d87 100644
--- a/Documentation/misc-devices/mei/mei-amt-version.c
+++ b/Documentation/misc-devices/mei/mei-amt-version.c
@@ -115,8 +115,6 @@ static bool mei_init(struct mei *me, const uuid_le *guid,
 	struct mei_client *cl;
 	struct mei_connect_client_data data;
 
-	mei_deinit(me);
-
 	me->verbose = verbose;
 
 	me->fd = open("/dev/mei", O_RDWR);
-- 
1.8.4.2

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