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Date:      Sat, 30 Jan 2016 20:23:18 +0100
From:      Hans Petter Selasky <hps@selasky.org>
To:        Slawa Olhovchenkov <slw@zxy.spb.ru>, mokhi <mokhi64@gmail.com>
Cc:        freebsd-current@freebsd.org
Subject:   Re: thread-unsafety problems as spl*() ones are NOP
Message-ID:  <56AD0DA6.3090502@selasky.org>
In-Reply-To: <20160130183131.GN88527@zxy.spb.ru>
References:  <CAByVWPWuqdtZ-5p2%2BvGf4v%2BPjjCBkiTQSsZQ06vk-f=bx_TQrQ@mail.gmail.com> <CAByVWPWQJ1wP95S59SiWWBa0k9j2%2Bu1az-D04_V1voo99CxqCw@mail.gmail.com> <20160130180256.GT37895@zxy.spb.ru> <CAByVWPUz2nMuWncsv648BGHReBvtP3r1afAz0LC%2BWD5tikdYDA@mail.gmail.com> <20160130182521.GM88527@zxy.spb.ru> <20160130183131.GN88527@zxy.spb.ru>

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On 01/30/16 19:31, Slawa Olhovchenkov wrote:
> On Sat, Jan 30, 2016 at 09:25:21PM +0300, Slawa Olhovchenkov wrote:
>
>> On Sat, Jan 30, 2016 at 09:42:13PM +0330, mokhi wrote:
>>
>>> i currently only wanna do patch on kbd.c (because i'm sure there is a
>>> thread-unsafety)
>>> and i don't want to add anything to spltty() nor splx(), i just wanna
>>> add things under where they've been used.
>>> isn't problem with using mutex/spin/lock/unlock etc there?
>>
>> yes.
>> currenly spltty act as mutex_lock(&spltty_mutex), like global lock for
>> all used files. this is also inter-files lock, not only lock inside
>> only kbd.c.
>> you need patch all files. all using spltty need to remove
>> simultaneously.
>>
>
> oh, sorry.
> i am see now all splXXX is nop.
> may be incorretly -- for example, in digi.c i am don't see any lockind
> instead spltty().

Hi,

Code that uses splxxx() needs to have the Giant lock locked when 
running. Refer to the various MPSAFE flags.

--HPS




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