On Fri, 27 Jun 2003, Greg KH wrote: > On Fri, Jun 27, 2003 at 04:45:12PM +0100, Ian Abbott wrote: > > Hello, > > > > I have borrowed Greg's changes in the Visor USB serial driver (2.5.x > > kernel) that replaces a fixed pool of write urbs with dynamically > > allocated write urbs, I want to use the same technique in the > > ftdi_sio driver. > > > > A simple 'dd' command to write several seconds worth of data to the > > serial port now returns pretty much instantly (because the > > 'chars_in_buffer' function pretends the data is already flushed). > > This leaves plenty of time to 'rmmod' the driver module while the > > data is still being transmitted, but this causes an Oops, > > presumably when the callback function gets called on completion of > > an urb. > > Yup, don't do that :) > > > I'm a newbie as far as the 2.5.x kernel is concerned, but MOD_INC... > > and MOD_DEC... seem to be frowned upon now, so what's the best way > > around this problem? I'm guessing it happens in the Visor driver > > too? > > Yes, this could happen in the visor driver too. > > As for how to solve this? The module reference count will be > incremented when the device is opened, right? Then on close, make sure > all urbs are flushed out before finishing the close function. > Unfortunatly, this seems to require keeping track of all pending urbs in > flight, which is kind of the opposite for doing what the visor driver is > doing...
A simple counter of active URBs would solve the problem. > There was some proposals for how to fix this in the past on the mailing > list, but I don't think they ever went very far. Alan Stern ------------------------------------------------------- This SF.Net email sponsored by: Free pre-built ASP.NET sites including Data Reports, E-commerce, Portals, and Forums are available now. Download today and enter to win an XBOX or Visual Studio .NET. http://aspnet.click-url.com/go/psa00100006ave/direct;at.asp_061203_01/01 _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
