Messages in this thread | | | From | Oliver Neukum <> | Subject | Re: [linux-usb-devel] Re: [PATCH 00/10] usb-serial: Switches from spin lock to atomic_t. | Date | Tue, 6 Dec 2005 23:36:47 +0100 |
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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.
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