Re: [PATCH 3/3] Make SCSI error handler code easier to understand

[Hannes Reinecke <hare@suse.de>]

On 05/26/2014 05:15 PM, Bart Van Assche wrote:
> Every now and then someone asks how it is avoided that the SCSI error
> handler and the SCSI completion handler are invoked concurrently for
> the same SCSI command. Add a few WARN_ON_ONCE() statements that make
> it clear how this is avoided.
>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: Jens Axboe <axboe@fb.com>
> Cc: Joe Lawrence <joe.lawrence@stratus.com>
> ---
>   drivers/scsi/scsi_error.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index 5232583..aee0dc0 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -120,6 +120,8 @@ scmd_eh_abort_handler(struct work_struct *work)
>   	struct scsi_device *sdev = scmd->device;
>   	int rtn;
>
> +	WARN_ON_ONCE(!blk_rq_completed(scmd->request));
> +
>   	if (scsi_host_eh_past_deadline(sdev->host)) {
>   		SCSI_LOG_ERROR_RECOVERY(3,
>   			scmd_printk(KERN_INFO, scmd,
> @@ -185,6 +187,8 @@ scsi_abort_command(struct scsi_cmnd *scmd)
>   	struct Scsi_Host *shost = sdev->host;
>   	unsigned long flags;
>
> +	WARN_ON_ONCE(!blk_rq_completed(scmd->request));
> +
>   	if (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED) {
>   		/*
>   		 * Retry after abort failed, escalate to next level.
> @@ -237,6 +241,8 @@ int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
>   	unsigned long flags;
>   	int ret = 0;
>
> +	WARN_ON_ONCE(!blk_rq_completed(scmd->request));
> +
>   	if (!shost->ehandler)
>   		return 0;
>
>
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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