Re: [PATCH] storvsc: add more logging for error and warning messages

[Joe Perches <joe@perches.com>]

On Thu, 2015-12-03 at 19:47 -0800, Long Li wrote:
> Introduce a logging level for storvsc to log certain error/warning
> messages. Those messages are helpful in some environments, e.g.
> Microsoft Azure, for customer support and troubleshooting purposes.
[]
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
[]
> +static inline bool do_logging(int level)
> +{
> +	return (logging_level >= level) ? true : false;

The ternary is not necessary

	return logging_level >= level;

is enough

> +}
> +
> +
>  struct vmscsi_win8_extension {
>  	/*
>  	 * The following were added in Windows 8
> @@ -1183,7 +1198,7 @@ static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
>  
>  	scmnd->result = vm_srb->scsi_status;
>  
> -	if (scmnd->result) {
> +	if (scmnd->result && do_logging(STORVSC_LOGGING_ERROR)) {
>  		if (scsi_normalize_sense(scmnd->sense_buffer,
>  				SCSI_SENSE_BUFFERSIZE, &sense_hdr))
>  			scsi_print_sense_hdr(scmnd->device, "storvsc",

Is it appropriate to make this scsi_normalize_sense call
conditional on do_logging here?

> @@ -1239,12 +1254,25 @@ static void storvsc_on_io_completion(struct hv_device *device,
>  	stor_pkt->vm_srb.sense_info_length =
>  	vstor_packet->vm_srb.sense_info_length;
>  
> +	if (vstor_packet->vm_srb.scsi_status != 0 ||
> +		vstor_packet->vm_srb.srb_status != SRB_STATUS_SUCCESS)
> +		if (do_logging(STORVSC_LOGGING_WARN))
> +			dev_warn(&device->device,
> +				"cmd 0x%x scsi status 0x%x srb status 0x%x\n",
> +				stor_pkt->vm_srb.cdb[0],
> +				vstor_packet->vm_srb.scsi_status,
> +				vstor_packet->vm_srb.srb_status);

It might make some sense to use another macro indirection like

#define svc_log_warn(dev, level, fmt, ...)			\
do {								\
	if (do_logging(STORSVC_LOGGING_##level)			\
		dev_warn(&(dev)->device, fmt, ##__VA_ARGS__);	\
} while (0)

So a use could be:

	if (vstore_packet...)
		svc_log_warn(device, WARN, ...);

>