On 08/19/05 15:38, Patrick Mansfield wrote: > On Fri, Aug 19, 2005 at 02:46:35PM -0400, Luben Tuikov wrote: > > >>Using the command time out hook and the strategy routine, gives _complete_ >>control over host recovery, and I really do mean _complete_. >> > > > I assume you mean hostt->eh_timed_out. Hi Patrick, how are you? Yes, this is what I meant, sorry for not being clear. > Is anyone implmenting (or has implemented) a ->eh_timed_out function? I see > none in mainline kernel. Yes, I have. > I was looking at using it in an LLDD, but hit two problems, and have > started to work on an alternate approach of cancelling (aborting or wtf you > want to call it) a list of commands in the eh thread. The eh_timed_out + eh_strategy_handler is actually pretty perfect, and _complete_, for any application and purpose in recovering a LU/device/host (in that order ;-) ). > The two problems I see with the hook are: > > It calls the driver in interrupt context, so the called function can't > sleep. Consider this: When SCSI Core told you that the command timed out, A) it has already finished, B) it hasn't already finished. In case A, you can return EH_HANDLED. In case B, you return EH_NOT_HANDLED, and deal with it in the eh_strategy_handler. (Hint: you can still "finish" it from there.) EH_RESET_TIMER is not really needed provided that - your interface infrastructure is in place, - you set the timeout value properly in slave_configure. > There is no queueing or list mechanism, so LLDD's that can only cancel one > command at a time will have problem. See above. Luben - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
