Messages in this thread | | | Date | Wed, 7 Dec 2005 10:25:40 -0200 | From | Luiz Fernando Capitulino <> | Subject | Re: [linux-usb-devel] Re: [PATCH 00/10] usb-serial: Switches from spin lock to atomic_t. |
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On Tue, 6 Dec 2005 23:36:47 +0100 Oliver Neukum <oliver@neukum.org> wrote:
| Am Dienstag, 6. Dezember 2005 22:18 schrieb Luiz Fernando Capitulino: | > | > 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. | | You can atomically set _one_ value using atomic_t. A spinlock allows | that and other more complex schemes.
We only need to set 'write_urb_busy', nothing more.
-- Luiz Fernando N. Capitulino - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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