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SubjectRe: [PATCH v3 1/3] scsi: Provide for avoiding trailing allocation length with VPD inquiries
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On 1/3/22 01:23, Christoph Hellwig wrote:
> On Sun, Jan 02, 2022 at 11:23:45PM +0000, Maciej W. Rozycki wrote:
>> Allow SCSI hosts to request avoiding trailing allocation length with VPD
>> inquiries, and use the mechanism to work around an issue with at least
>> some BusLogic MultiMaster host bus adapters and observed with the BT-958
>> model specifically where issuing commands that return less data than
>> provided for causes fatal failures:
> Wouldn't it make more sesnse to hide this quirk insde of
> scsi_vpd_inquiry to also handle the scsi_get_vpd_buf case? Something
> like:
>
>
> diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
> index 211aace69c22c..194a51f772aaa 100644
> --- a/drivers/scsi/scsi.c
> +++ b/drivers/scsi/scsi.c
> @@ -289,8 +289,8 @@ EXPORT_SYMBOL(scsi_track_queue_full);
> *
> * Returns size of the vpd page on success or a negative error number.
> */
> -static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
> - u8 page, unsigned len)
> +static int __scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
> + u8 page, unsigned len)
> {
> int result;
> unsigned char cmd[16];
> @@ -321,6 +321,20 @@ static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
> return get_unaligned_be16(&buffer[2]) + 4;
> }
>
> +static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
> + u8 page, unsigned len)
> +{
> + if (sdev->host->no_trailing_allocation_length) {
> + int ret = __scsi_vpd_inquiry(sdev, buffer, page, min(4U, len));
> +
> + if (ret < 4)
> + return ret;
> + len = min_t(unsigned int, ret, len);
> + }
> +
> + return __scsi_vpd_inquiry(sdev, buffer, page, len);
> +}
> +
> /**
> * scsi_get_vpd_page - Get Vital Product Data from a SCSI device
> * @sdev: The device to ask

This is certainly better. It consolidates all the special cases for
getting VPD pages in one location and ensures no cases are missed.

--
Khalid

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