On Mon, 4 Feb 2008, Lal wrote: > I have developed a sample USB mass storage driver. Using this driver, > I can mount file system on my CF card, and can read/write small files > to/from CF card. However, the driver crashes while reading/writing > large files. > From kernel stack trace, it seems there is some synchronization issue > with interrupts. I see kernel stack something like this:
> Looking at the stack trace, it seems, some locking mechanism is > required. I am referring to LDD3 chapter 13 (USB Drivers) and chapter > 16 (Block drivers). The driver does USB read/write as follows: > > my_request_queue_function > check if request is read or write > allocate and fill urb (using req->sector and req->current_nr_sectors) > submit urb > wait to complete > copy data to req->buffer > during this process, I have not taken any lock. Can someone give some > hint, if some lock is required here? > I do not submit any urb in complete function of usb_fill_bulk_urb. I > am not able to get which other part can be executed in interrupt > context (if I am right, request queue function is not called in > interrupt context). I believe you are wrong: The request_queue function _is_ called in an atomic context. Hence your "wait to complete" step is problematic. Alan Stern - To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
