linux-kernel - Re: [PATCH] sound: don't use the deprecated function check

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Date:	Mon, 8 Aug 2011 17:33:40 +0800
From:	Wang Shaoyan <stufever@...il.com>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	linux-kernel@...r.kernel.org, perex@...ex.cz,
	Wang Shaoyan <wangshaoyan.pt@...bao.com>
Subject: Re: [PATCH] sound: don't use the deprecated function check_region

2011/8/8 Takashi Iwai <tiwai@...e.de>:
> At Mon,  8 Aug 2011 16:07:12 +0800,
> stufever@...il.com wrote:
>>
>> From: Wang Shaoyan <wangshaoyan.pt@...bao.com>
>>
>>   sound/oss/pss.c: In function 'configure_nonsound_components':
>>   sound/oss/pss.c:676: warning: 'check_region' is deprecated (declared at include/linux/ioport.h:201)
>>
>> Signed-off-by: Wang Shaoyan <wangshaoyan.pt@...bao.com>
>> ---
>>  sound/oss/pss.c |    3 ++-
>>  1 files changed, 2 insertions(+), 1 deletions(-)
>>
>> diff --git a/sound/oss/pss.c b/sound/oss/pss.c
>> index 9b800ce..0fa26bd 100644
>> --- a/sound/oss/pss.c
>> +++ b/sound/oss/pss.c
>> @@ -673,9 +673,10 @@ static void configure_nonsound_components(void)
>>
>>       if (pss_cdrom_port == -1) {     /* If cdrom port enablation wasn't requested */
>>               printk(KERN_INFO "PSS: CDROM port not enabled.\n");
>> -     } else if (check_region(pss_cdrom_port, 2)) {
>> +     } else if (!request_region(pss_cdrom_port, 2, "PSS CDROM")) {
>>               printk(KERN_ERR "PSS: CDROM I/O port conflict.\n");
>>       } else {
>> +             release_region(pss_cdrom_port, 2);
>>               set_io_base(devc, CONF_CDROM, pss_cdrom_port);
>>               printk(KERN_INFO "PSS: CDROM I/O port set to 0x%x.\n", pss_cdrom_port);
>>       }
>
> Well, this just hides the warning but doesn't fix the possible race,
> which is the reason check_region() is marked as deprecated after all.
>

AFAIK, check_region() is deprecated because such usage:
check_region()
...do something    <-- here another process may do check and request same region
request_region()
But nowadays, request_region has done the check internally, so use the
proper request_region to check is enough, am I miss something?

> Instead of releasing the resource there, keep it and release in the
> destructor properly like other normal resources.
>

maybe we can release here?

set_io_base(devc, CONF_CDROM, pss_cdrom_port);
printk(KERN_INFO "PSS: CDROM I/O port set to 0x%x.\n", pss_cdrom_port);
release_region(pss_cdrom_port, 2);

>
> thanks,
>
> Takashi
>



-- 
Wang Shaoyan
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