linux-kernel - Re: [PATCH]drivers/ata/libata-eh.c:1509 unneeded memset()

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Date:	Mon, 11 Jan 2010 21:18:02 +0100
From:	René Bolldorf <xsecute@...glemail.com>
To:	Marc Bejarano <beej@...j.org>
CC:	linux-scsi@...r.kernel.org, linux-ide@...r.kernel.org,
	James Bottomley <James.Bottomley@...e.de>,
	linux-kernel@...r.kernel.org, jgarzik@...ox.com
Subject: Re: [PATCH]drivers/ata/libata-eh.c:1509 unneeded memset()

On 01/11/10 20:41, Marc Bejarano wrote:
> and once more in plain text.  (sorry vger)
>
> 2010/1/11 Marc Bejarano<beej@...j.org>:
>> oops.  seems that GMANE's reply function only goes to a single "newsgroup".
>>   original recipients re-added.
>> marc
>> ----
>> From: Marc Bejarano<beej<at>  beej.org>
>> Subject: Re: [PATCH]drivers/ata/libata-eh.c:1509 unneeded memset()
>> Newsgroups: gmane.linux.scsi
>> Date: 2010-01-08 22:21:09 GMT (2 days, 20 hours and 40 minutes ago)
>>
>> René Bolldorf<xsecute<at>  googlemail.com>  writes:
>>> On 01/08/10 16:28, James Bottomley wrote:
>>>> On Thu, 2010-01-07 at 14:15 -0500, Jeff Garzik wrote:
>>>>> On 12/30/2009 05:59 PM, René Bolldorf wrote:
>>>>>> We don't need this .
>>
>>>>>> - /* FIXME: is this needed? */
>>>>>> - memset(sense_buf, 0, SCSI_SENSE_BUFFERSIZE);
>>>>>
>>>>> I need a little bit more detail than an unqualified statement...  Did
>>>>> you audit all paths leading to this code point?
>>
>>>> But one also here:
>>>>
>>>> u8 *sense_buffer = dev->link->ap->sector_buf;
>>>> [...]
>>>> err_mask = atapi_eh_request_sense(dev, sense_buffer, sense_key);
>>>>
>>>> Which doesn't look OK because it looks like the sector_buf isn't cleared
>>>> (and it is reused).
>>>>
>>>> James
>>>>
>>>>
>>>
>>> Thank's, you're right. I have overseen this, sry for that.
>>
>> René: perhaps you'd like to submit a patch that substitutes FIXME comment
>> for one that explains why the memset is needed, crediting James in the
>> description?  we may as well gain something permanent from this discussion
>> that you started :)
>>
>> cheers,
>> marc
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
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>>
>> ----

I hope that's good enough explained :-).

Best regards
René

--- ./drivers/ata/libata-eh.c   2010-01-07 23:21:23.622464012 +0100
+++ ./drivers/ata/libata-eh.c   2010-01-11 21:11:19.869092897 +0100
@@ -1505,7 +1505,10 @@ static unsigned int atapi_eh_request_sen

         DPRINTK("ATAPI request sense\n");

-       /* FIXME: is this needed? */
+       /* make sure sense_buf is cleared then atapi_eh_request_sense is 
called.
+        * (to make sure nothing get's reused.)
+        * thanks to James Bottomley
+        */
         memset(sense_buf, 0, SCSI_SENSE_BUFFERSIZE);

         /* initialize sense_buf with the error register,
--
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