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From: Cyrill Gorcunov <>
To: Jiri Slaby <>
Cc: Paul Gortmaker <>,
	LKML <>, Andi Kleen <>,
	Alexey Dobriyan <>
Subject: Re: [PATCH] driver: ip27-rtc - convert ioctl to unlocked_ioctl
Date: Mon, 14 Jan 2008 18:38:06 +0300	[thread overview]
Message-ID: <20080114153806.GA6639@cvg> (raw)
In-Reply-To: <>

[Jiri Slaby - Mon, Jan 14, 2008 at 04:14:18PM +0100]
> On 01/14/2008 07:38 AM, Cyrill Gorcunov wrote:
>> This patch converts ioctl call to unlocked_ioctl form. It's possible
>> due to rtl_lock spinlock protection.
>> Signed-off-by: Cyrill Gorcunov <>
>> ---
>> The patch is *not* tested but the patch does not bring _much_ changes
>> so it wouldn't break the compilation procedure.
>> If there is problem with attachment - i could send it as inline
>> form today evening.
> Yes, please, especially if it is app/octet-stream (base64 encoded 
> plaintext). Also Cc akpm or somebody who will pick your patch up.


>> Andi, Jiri, Alexey the only thing I do complain about -
>> is time set/read from several user threads that uses same
>> (duplicated) file descriptor. Could there be useless thread
>> spins instead of sleep (in case if this unlocked_ioctl were
>> protected by mutex)?
> Sorry, what?

Jiri, I mean rtc_open() is protected by spinlock+status from being
opened simultaneously by a few processes. *But* lets imagine the
following situation - this fd (file descriptor) is opened by one
multithreaded application so all threads have an access to this
fd. Then one thread reads rtc periodically thru unlocked_ioctl
and another thread set new time from time to time. So the question
I have - is it possible to get second thread stopped at attemption to
get rtc spinlock while another thread is setting the new time? Or
this situation never-ever could be? i'm not really familiar with
process management in Linux and as result could be wrong.

		- Cyrill -

  reply	other threads:[~2008-01-14 15:38 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-13 20:32 [PATCH] driver: ip27-rtc - convert ioctl to unlocked_ioctl Cyrill Gorcunov
2008-01-13 21:07 ` Alexey Dobriyan
2008-01-13 21:25   ` Cyrill Gorcunov
2008-01-13 21:22 ` Jiri Slaby
2008-01-13 21:29   ` Jiri Slaby
2008-01-13 21:32     ` Cyrill Gorcunov
2008-01-14  6:38       ` Cyrill Gorcunov
2008-01-14 15:14         ` Jiri Slaby
2008-01-14 15:38           ` Cyrill Gorcunov [this message]
2008-01-14 15:59             ` Jiri Slaby
2008-01-14 16:07               ` Cyrill Gorcunov
2008-01-14 16:27                 ` Jiri Slaby
2008-01-14 16:28                   ` Cyrill Gorcunov
2008-01-13 23:08 ` Andi Kleen

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