Date: Mon, 21 Feb 2011 11:38:15 +0100 From: Svatopluk Kraus <onwahe@gmail.com> To: freebsd-hackers@freebsd.org Cc: Hans Petter Selasky <hselasky@c2i.net> Subject: Re: ichsmb - correct locking strategy? Message-ID: <AANLkTik%2BrCywN6hUun-2xR7eFfd-OWnBaPcoyZAwPDir@mail.gmail.com> In-Reply-To: <201102181609.39955.hselasky@c2i.net> References: <AANLkTinv8EkNqvQaNWpbW_q8J8kqSiJuLSb3j5S842a=@mail.gmail.com> <201102181609.39955.hselasky@c2i.net>
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On Fri, Feb 18, 2011 at 4:09 PM, Hans Petter Selasky <hselasky@c2i.net> wro=
te:
> On Friday 18 February 2011 15:10:47 Svatopluk Kraus wrote:
>> Hi,
>>
>> =A0 I try to figure out locking strategy in FreeBSD and found 'ichsmb'
>> device. There is a mutex which protects smb bus (ichsmb device). For
>> example in ichsmb_readw() in sys/dev/ichsmb/ichsmb.c, the mutex is
>> locked and a command is written to bus, then unbounded (but with
>> timeout) sleep is done (mutex is unlocked during sleep). After sleep a
>> word is read from bus and the mutex is unlocked.
>>
>> =A0 1. If an use of the device IS NOT serialized by layers around then
>> more calls to this function (or others) can be started or even done
>> before the first one is finished. The mutex don't protect sms bus.
>>
>> =A0 2. If an use of the device IS serialized by layers around then the
>> mutex is useless.
>>
>> =A0 Moreover, I don't mension interrupt routine which uses the mutex and
>> smb bus too.
>>
>> =A0 Am I right? Or did I miss something?
>
> man sx ?
>
> struct sx ?
>
> --HPS
>
Thanks for your reply. It seems that everybody knows that ichsmb
driver is not in good shape but nobody cares for ...
Svata
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