Re: [PATCH 1/3] Remove two cancel_delayed_work() calls from the error handler

[Paolo Bonzini <pbonzini@redhat.com>]

Il 26/05/2014 17:14, Bart Van Assche ha scritto:
> scsi_put_command() is either invoked before a command is queued or
> after a command has completed. scsi_cmnd.abort_work is scheduled
> after a command has timed out and before it is finished. The block
> layer guarantees that either the softirq_done_fn() or the
> rq_timed_out_fn() function is invoked but not both. This means that
> scsi_put_command() is never invoked while abort_work is scheduled.
> Hence remove the cancel_delayed_work() call from scsi_put_command().
>
> Similarly, scsi_abort_command() is only invoked from the SCSI
> timeout handler. If scsi_abort_command() is invoked for a SCSI
> command with the SCSI_EH_ABORT_SCHEDULED flag set this means that
> scmd_eh_abort_handler() has already invoked scsi_queue_insert() and
> hence that scsi_cmnd.abort_work is no longer pending. Hence also
> remove the cancel_delayed_work() call from scsi_abort_command().
>
> 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.c       | 2 +-
>  drivers/scsi/scsi_error.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
> index 88d46fe..c972eab 100644
> --- a/drivers/scsi/scsi.c
> +++ b/drivers/scsi/scsi.c
> @@ -334,7 +334,7 @@ void scsi_put_command(struct scsi_cmnd *cmd)
>  	list_del_init(&cmd->list);
>  	spin_unlock_irqrestore(&cmd->device->list_lock, flags);
>
> -	cancel_delayed_work(&cmd->abort_work);
> +	WARN_ON_ONCE(delayed_work_pending(&cmd->abort_work));
>
>  	__scsi_put_command(cmd->device->host, cmd);
>  }
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index f17aa7a..5232583 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -193,7 +193,7 @@ scsi_abort_command(struct scsi_cmnd *scmd)
>  		SCSI_LOG_ERROR_RECOVERY(3,
>  			scmd_printk(KERN_INFO, scmd,
>  				    "scmd %p previous abort failed\n", scmd));
> -		cancel_delayed_work(&scmd->abort_work);
> +		WARN_ON_ONCE(delayed_work_pending(&scmd->abort_work));
>  		return FAILED;
>  	}
>
>

I still prefer a BUG_ON in scsi_put_command, but anyway: series

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>