On Wed, Nov 23, 2005 at 09:36:55AM -0200, Luiz Fernando Capitulino wrote:
> On Tue, 22 Nov 2005 14:13:53 -0800
> Greg KH <[EMAIL PROTECTED]> wrote:
>
> | On Tue, Nov 22, 2005 at 07:59:26PM -0200, Luiz Fernando Capitulino wrote:
> | > @@ -60,6 +61,7 @@ struct usb_serial_port {
> | > struct usb_serial * serial;
> | > struct tty_struct * tty;
> | > spinlock_t lock;
> | > + struct semaphore sem;
> |
> | You forgot to document what this semaphore is used for.
>
> Okay.
>
> | Hm, can we just use the spinlock already present in the port structure
> | for this? Well, drop the spinlock and use the semaphore? Yeah, that
> | means grabbing a semaphore for ever write for some devices, but USB data
> | rates are slow enough it wouldn't matter :)
>
> As far as I read the code, I found that spinlock is only used by the
> generic driver, in the
> drivers/usb/serial/generic.c:usb_serial_generic_write() function.
No, lots of other usb-serial drivers use it. Increase your grep a bit
wider :)
> Can we drop the spinlock there and use our new semaphore? Or should we
> create a new spinlock just to use there?
Create a new one for where?
> I ask it because the semaphore will be used to serialize open()/close()
> operations in the usb-serial driver, is a bit weird to use the same
> semaphore in a write() function of other driver.
I agree, but yet-another-lock isn't the best either.
thanks,
greg k-h
-------------------------------------------------------
This SF.net email is sponsored by: Splunk Inc. Do you grep through log files
for problems? Stop! Download the new AJAX search engine that makes
searching your log files as easy as surfing the web. DOWNLOAD SPLUNK!
http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click
_______________________________________________
linux-usb-devel@lists.sourceforge.net
To unsubscribe, use the last form field at:
https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
