On Thu, 14 Jul 2005 22:06:04 -0400 (EDT), Alan Stern <[EMAIL PROTECTED]> wrote:
> > But calling this cancel adds an opportunity for racing somewhere. > > No it doesn't. The opportunity was there all along. Remember, the caller > could call usb_sg_cancel from another thread at precisely this time. I don't think ub does that. > Trusting unlinks is a separate matter. However I think they are pretty > well under control now. I can't recall hearing of any problems in the HCD > code relating to buggy unlinks for quite some time. OK, yes, they are much better than used to be. But still, I think that invoking an unlink doesn't save us anything. Not having a call to sg_cancel there is one more obstacle to factoring submission out from usb_sg_wait like you proposed, but that is hindered by other things as well (e.g. yield()). If those are gone, I'll think about it again. BTW, I think I saw an unlink which did not return a callback today. Not crashing, granted. It happens very infrequently... I saved a trace accidentially: d83010e8 697580560 S Bo:005:01 -115 31 = 55534243 1b000000 00080000 80000a28 00000000 00000001 00000000 000000 d83010e8 697580611 C Bo:005:01 0 31 > d83010e8 697580641 S Bi:005:02 -115 2048 < d83010e8 697580862 C Bi:005:02 0 0 d83010e8 697580895 S Bi:005:02 -115 13 < d83010e8 697580986 C Bi:005:02 -32 0 d83010e8 697581018 S Co:005:00 s 02 01 0000 0082 0000 0 d83010e8 697581112 C Co:005:00 0 0 d83010e8 697581140 S Bi:005:02 -115 13 < d83010e8 697581236 C Bi:005:02 0 13 = 55534253 1b000000 00080000 01 d83010e8 697581267 S Bi:005:02 -115 13 < d83010e8 881232539 C Bi:005:02 -71 0 <------ pulled plug d83010e8 881232612 S Bi:005:02 -115 13 < d83010e8 881232777 C Bi:005:02 -71 0 d83010e8 881232820 S Bo:005:01 -115 31 = 55534243 1d000000 12000000 80000603 00000012 00000000 00000000 000000 d83010e8 881232901 C Bo:005:01 -71 0 Look at the jump in the timestamp. It's where I became tired from waiting and pulled the cable. The unlink itself is not captured by usbmon, because they are rather reliable normally, and you see a callback with status -104. I skipped on implementing that. But I guarantee you that ub tries an unlink from a timer. -- Pete ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&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
