On Mon, 14 Jan 2013, Sergei Shtylyov wrote: > Serialize usb-storage operations with usbfs and 'cat /proc/bus/usb/devices', > so that they cannot disturb storage by seemingly harmless control reads. > > This patch was adapted from 2.4.28 patch by Pete Zaitcev -- which I even had to > reconstruct as I have never found it in its final form. That patch dates back > to 2004 and it unfortunately wasn't applied to 2.6 branch in the same form back > then (it was applied in another form and then immediately reverted). Despite 8+ > years passing from that moment, the vendors didn't stop producing USB devices > that require this patch. Two recent examples are SanDisk Cruzer Slice 8GB and > Kingston DataTraveller 100 G2 32GB. In the latter case, even the enumeration > fails as the INQUIRY command takes 2.8 seconds to finish, so 'udev' also comes > into action with its control requests, with neither completing normally. Without commenting on the wisdom of this patch, there are a couple of places where the comments could be improved. > --- usb.orig/drivers/usb/core/devices.c > +++ usb/drivers/usb/core/devices.c > @@ -423,21 +423,30 @@ static char *usb_dump_desc(char *start, > if (start > end) > return start; > > + /* > + * Grab device's exclusive_access mutex to prevent its driver or > + * devio from using this device while we are accessing it. s/devio/usbfs/ > --- usb.orig/drivers/usb/storage/transport.c > +++ usb/drivers/usb/storage/transport.c > @@ -601,9 +601,18 @@ void usb_stor_invoke_transport(struct sc > int need_auto_sense; > int result; > > + /* > + * Grab device's exclusive_access mutex to prevent libusb/usbfs from > + * sending out a command in the middle of ours (if libusb sends a > + * get_descriptor or something on pipe 0 after our CBW and before s/pipe 0/ep0/ Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
