On 03/08/2016 02:01 PM, Hannes Reinecke wrote: > On 03/08/2016 01:35 PM, Yaniv Gardi wrote: >> A race condition exists between request requeueing and scsi layer >> error handling: >> When UFS driver queuecommand returns a busy status for a request, >> it will be requeued and its tag will be freed and set to -1. >> At the same time it is possible that the request will timeout and >> scsi layer will start error handling for it. The scsi layer reuses >> the request and its tag to send error related commands to the device, >> however its tag is no longer valid. >> As this request was never really sent to the device, there is no >> point to start error handling with the device. >> Implement the scsi error handling timeout callback and bypass SCSI >> error handling for request that were not actually sent to the device. >> For such requests simply reset the block layer timer. Otherwise, let >> SCSI layer perform the usual error handling. >> >> Reviewed-by: Dolev Raviv <dra...@codeaurora.org> >> Signed-off-by: Gilad Broner <gbro...@codeaurora.org> >> Signed-off-by: Yaniv Gardi <yga...@codeaurora.org> >> >> --- >> drivers/scsi/ufs/ufshcd.c | 36 ++++++++++++++++++++++++++++++++++++ >> 1 file changed, 36 insertions(+) >> > Having a timeout handler is always a good idea, even though this > doesn't do anything here. > Are we sure that the requests will return eventually? > Does the UFS spec provide for a command abort? > In fact, looking at the UFS spec there _is_ a command abort. I would recommend implementing a task management request UPIO with type 'ABORT TASK' here for any task found to be pending. In the end, you might run into a _valid_ timeout, at which point you really want to abort the command...
Cheers, Hannes- -- Dr. Hannes Reinecke Teamlead Storage & Networking h...@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)
