From: Greg KH <gregkh@suse.de>
To: Luiz Fernando Capitulino <lcapitulino@mandriva.com.br>
Cc: 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.
Date: Tue, 6 Dec 2005 11:40:41 -0800 [thread overview]
Message-ID: <20051206194041.GA22890@suse.de> (raw)
In-Reply-To: <20051206095610.29def5e7.lcapitulino@mandriva.com.br>
On Tue, Dec 06, 2005 at 09:56:10AM -0200, Luiz Fernando Capitulino wrote:
> Greg,
>
> Don't get scared. :-)
>
> As showed by Eduardo Habkost some days ago, the spin lock 'lock' in the
> struct 'usb_serial_port' is being used by some USB serial drivers to protect
> the access to the 'write_urb_busy' member of the same struct.
>
> The spin lock however, is needless: we can change 'write_urb_busy' type
> to be atomic_t and remove all the spin lock usage.
But if you do that, you make things slower on non-smp machines, which
isn't very nice. Why does the spinlock bother you?
thanks,
greg k-h
next prev parent reply other threads:[~2005-12-06 19:41 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-06 11:56 [PATCH 00/10] usb-serial: Switches from spin lock to atomic_t Luiz Fernando Capitulino
2005-12-06 19:40 ` Greg KH [this message]
2005-12-06 20:13 ` Eduardo Pereira Habkost
2005-12-06 22:48 ` [linux-usb-devel] " Oliver Neukum
2005-12-07 12:24 ` Luiz Fernando Capitulino
2005-12-07 12:27 ` Arjan van de Ven
2005-12-07 12:30 ` Luiz Fernando Capitulino
2005-12-07 12:34 ` Arjan van de Ven
2005-12-07 12:41 ` Luiz Fernando Capitulino
2005-12-07 12:54 ` Luiz Fernando Capitulino
2005-12-07 15:07 ` Alan Stern
2005-12-07 15:22 ` Arjan van de Ven
2005-12-07 15:37 ` Oliver Neukum
2005-12-07 15:40 ` Arjan van de Ven
2005-12-07 15:50 ` Oliver Neukum
2005-12-07 16:02 ` Alan Cox
2005-12-07 16:00 ` Eduardo Pereira Habkost
2005-12-07 16:02 ` Arjan van de Ven
2005-12-07 16:23 ` Eduardo Pereira Habkost
2005-12-07 16:01 ` Alan Stern
2005-12-07 16:04 ` Arjan van de Ven
2005-12-07 15:32 ` linux-os (Dick Johnson)
2005-12-07 16:08 ` Alan Stern
2005-12-06 20:14 ` Luiz Fernando Capitulino
2005-12-06 21:02 ` Pete Zaitcev
2005-12-06 21:18 ` Luiz Fernando Capitulino
2005-12-06 22:36 ` [linux-usb-devel] " Oliver Neukum
2005-12-07 12:25 ` Luiz Fernando Capitulino
2005-12-07 13:01 ` Oliver Neukum
2005-12-07 13:17 ` Luiz Fernando Capitulino
2005-12-07 16:41 ` Greg KH
2005-12-07 16:51 ` Luiz Fernando Capitulino
2005-12-07 17:13 ` Eduardo Pereira Habkost
2005-12-07 17:56 ` Greg KH
2005-12-07 19:10 ` Eduardo Pereira Habkost
2005-12-07 16:55 ` Otavio Salvador
2005-12-07 16:59 ` Greg KH
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