Date: Tue, 6 Dec 2005 19:18:45 -0200
From: Luiz Fernando Capitulino <lcapitulino@mandriva.com.br>
To: Pete Zaitcev <zaitcev@redhat.com>
Cc: gregkh@suse.de, linux-kernel@vger.kernel.org,
       linux-usb-devel@lists.sourceforge.net, ehabkost@mandriva.com
Subject: Re: [PATCH 00/10] usb-serial: Switches from spin lock to atomic_t.
Message-Id: <20051206191845.6f4827b3.lcapitulino@mandriva.com.br>
In-Reply-To: <20051206130207.7658636e.zaitcev@redhat.com>
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	<20051206194041.GA22890@suse.de>
	<20051206181449.11947f4f.lcapitulino@mandriva.com.br>
	<20051206130207.7658636e.zaitcev@redhat.com>
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 Hi Pete,

On Tue, 6 Dec 2005 13:02:07 -0800
Pete Zaitcev <zaitcev@redhat.com> wrote:

| On Tue, 6 Dec 2005 18:14:49 -0200, Luiz Fernando Capitulino <lcapitulino@mandriva.com.br> wrote:
| 
| >  The spinlock makes the code less clear, error prone, and we already a
| > semaphore in the struct usb_serial_port.
| > 
| >  The spinlocks _seems_ useless to me.
| 
| Dude, semaphores are not compatible with interrupts. Surely you
| understand that?

 Sure thing man, take a look at this thread:

http://marc.theaimsgroup.com/?l=linux-kernel&m=113216151918308&w=2

 My comment 'we already have a semaphore in struct usb_serial_port'
was about what we've discussed in that thread, where question like
'why should we have yet another lock here?' have been made.

 And *not* 'let's use the semaphore instead'.

 If _speed_ does not make difference, the spinlock seems useless,
because we could use atomic_t instead.

-- 
Luiz Fernando N. Capitulino
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