Re: [PATCH] scsi: core: Add BLIST_NO_ASK_VPD_SIZE for some VDASD

[Lee Duncan]

On Mar 3, 2023, at 1:02 AM, Linux regression tracking (Thorsten Leemhuis) <regressions@xxxxxxxxxxxxx> wrote:
> 
> Hi, this is your Linux kernel regression tracker.
> 
> On 28.09.22 20:13, Lee Duncan wrote:
>> From: Lee Duncan <lduncan@xxxxxxxx>
>> 
>> Some storage, such as AIX VDASD (virtual storage) and IBM 2076
>> (front end) do not like the recent commit:
>> 
>> commit c92a6b5d6335 ("scsi: core: Query VPD size before getting full page")
>> 
>> That commit changed getting SCSI VPD pages so that we now read
>> just enough of the page to get the actual page size, then read
>> the whole page in a second read. The problem is that the above
>> mentioned hardware returns zero for the page size, because of
>> a firmware error. In such cases, until the firmware is fixed,
>> this new black flag says to revert to the original method of
>> reading the VPD pages, i.e. try to read as a whole buffer's
>> worth on the first try.
> 
> As this is a fix for a regression (one that Srikar Dronamraju recently
> ran into as well and bisected again :-/ ), please allow me to ask:
> 
> James, Martin, what is needed to get this or some other solution for the
> regression finally mainlined?
> 
> FWIW, the thread afaics accumulated three Reviewed-by an one Tested-by
> in the meantime.
> 
> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
> --
> Everything you wanna know about Linux kernel regression tracking:
> https://linux-regtracking.leemhuis.info/about/#tldr
> If I did something stupid, please tell me, as explained on that page.
> 
> #regzbot poke

Martin:

I know you had reservations about this approach, but the fact that another
case has shown up where this patch helps means this isn’t just a one-off
problem.

I know the alternative was to have the code that reads mode pages just
automatically handle all cases where the size was returned to zero, but
I really prefer specifically listing “offending” hardware, rather than
automatically covering for it.

Please let me know if you still have reservations. If not, I could rebase
and resubmit this, if you like.

Thanks.

> 
>> Fixes: c92a6b5d6335 ("scsi: core: Query VPD size before getting full page")
>> Reported-by: Martin Wilck <mwilck@xxxxxxxx>
>> Suggested-by: Hannes Reinecke <hare@xxxxxxx>
>> Signed-off-by: Lee Duncan <lduncan@xxxxxxxx>
>> ---
>> drivers/scsi/scsi.c         | 14 +++++++++++---
>> drivers/scsi/scsi_devinfo.c |  3 ++-
>> drivers/scsi/scsi_scan.c    |  3 +++
>> include/scsi/scsi_device.h  |  2 ++
>> include/scsi/scsi_devinfo.h |  6 +++---
>> 5 files changed, 21 insertions(+), 7 deletions(-)
>> 
>> diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
>> index c59eac7a32f2..f2db4b846190 100644
>> --- a/drivers/scsi/scsi.c
>> +++ b/drivers/scsi/scsi.c
>> @@ -321,11 +321,19 @@ static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
>> return get_unaligned_be16(&buffer[2]) + 4;
>> }
>> 
>> -static int scsi_get_vpd_size(struct scsi_device *sdev, u8 page)
>> +static int scsi_get_vpd_size(struct scsi_device *sdev, u8 page, int buf_len)
>> {
>> unsigned char vpd_header[SCSI_VPD_HEADER_SIZE] __aligned(4);
>> int result;
>> 
>> + /*
>> + * if this hardware is blacklisted then don't bother asking
>> + * the page size, since it will repy with zero -- just assume it
>> + * is the buffer size
>> + */
>> + if (sdev->no_ask_vpd_sz_first)
>> + return buf_len;
>> +
>> /*
>> * Fetch the VPD page header to find out how big the page
>> * is. This is done to prevent problems on legacy devices
>> @@ -367,7 +375,7 @@ int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
>> if (!scsi_device_supports_vpd(sdev))
>> return -EINVAL;
>> 
>> - vpd_len = scsi_get_vpd_size(sdev, page);
>> + vpd_len = scsi_get_vpd_size(sdev, page, buf_len);
>> if (vpd_len <= 0)
>> return -EINVAL;
>> 
>> @@ -402,7 +410,7 @@ static struct scsi_vpd *scsi_get_vpd_buf(struct scsi_device *sdev, u8 page)
>> struct scsi_vpd *vpd_buf;
>> int vpd_len, result;
>> 
>> - vpd_len = scsi_get_vpd_size(sdev, page);
>> + vpd_len = scsi_get_vpd_size(sdev, page, SCSI_VPD_PG_LEN);
>> if (vpd_len <= 0)
>> return NULL;
>> 
>> diff --git a/drivers/scsi/scsi_devinfo.c b/drivers/scsi/scsi_devinfo.c
>> index c7080454aea9..d2b2e841e570 100644
>> --- a/drivers/scsi/scsi_devinfo.c
>> +++ b/drivers/scsi/scsi_devinfo.c
>> @@ -134,7 +134,7 @@ static struct {
>> {"3PARdata", "VV", NULL, BLIST_REPORTLUN2},
>> {"ADAPTEC", "AACRAID", NULL, BLIST_FORCELUN},
>> {"ADAPTEC", "Adaptec 5400S", NULL, BLIST_FORCELUN},
>> - {"AIX", "VDASD", NULL, BLIST_TRY_VPD_PAGES},
>> + {"AIX", "VDASD", NULL, BLIST_TRY_VPD_PAGES | BLIST_NO_ASK_VPD_SIZE},
>> {"AFT PRO", "-IX CF", "0.0>", BLIST_FORCELUN},
>> {"BELKIN", "USB 2 HS-CF", "1.95",  BLIST_FORCELUN | BLIST_INQUIRY_36},
>> {"BROWNIE", "1200U3P", NULL, BLIST_NOREPORTLUN},
>> @@ -188,6 +188,7 @@ static struct {
>> {"HPE", "OPEN-", "*", BLIST_REPORTLUN2 | BLIST_TRY_VPD_PAGES},
>> {"IBM", "AuSaV1S2", NULL, BLIST_FORCELUN},
>> {"IBM", "ProFibre 4000R", "*", BLIST_SPARSELUN | BLIST_LARGELUN},
>> + {"IBM", "2076", NULL, BLIST_NO_ASK_VPD_SIZE},
>> {"IBM", "2105", NULL, BLIST_RETRY_HWERROR},
>> {"iomega", "jaz 1GB", "J.86", BLIST_NOTQ | BLIST_NOLUN},
>> {"IOMEGA", "ZIP", NULL, BLIST_NOTQ | BLIST_NOLUN},
>> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
>> index 5d27f5196de6..b67743e32089 100644
>> --- a/drivers/scsi/scsi_scan.c
>> +++ b/drivers/scsi/scsi_scan.c
>> @@ -1056,6 +1056,9 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
>> else if (*bflags & BLIST_SKIP_VPD_PAGES)
>> sdev->skip_vpd_pages = 1;
>> 
>> + if (*bflags & BLIST_NO_ASK_VPD_SIZE)
>> + sdev->no_ask_vpd_sz_first = 1;
>> +
>> transport_configure_device(&sdev->sdev_gendev);
>> 
>> if (sdev->host->hostt->slave_configure) {
>> diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
>> index 2493bd65351a..5d15784ccefc 100644
>> --- a/include/scsi/scsi_device.h
>> +++ b/include/scsi/scsi_device.h
>> @@ -145,6 +145,7 @@ struct scsi_device {
>> const char * model; /* ... after scan; point to static string */
>> const char * rev; /* ... "nullnullnullnull" before scan */
>> 
>> +#define SCSI_VPD_PG_LEN 255 /* default SCSI VPD page size (max) */
>> struct scsi_vpd __rcu *vpd_pg0;
>> struct scsi_vpd __rcu *vpd_pg83;
>> struct scsi_vpd __rcu *vpd_pg80;
>> @@ -214,6 +215,7 @@ struct scsi_device {
>> * creation time */
>> unsigned ignore_media_change:1; /* Ignore MEDIA CHANGE on resume */
>> unsigned silence_suspend:1; /* Do not print runtime PM related messages */
>> + unsigned no_ask_vpd_sz_first:1; /* Do not ask for VPD size first */
>> 
>> unsigned int queue_stopped; /* request queue is quiesced */
>> bool offline_already; /* Device offline message logged */
>> diff --git a/include/scsi/scsi_devinfo.h b/include/scsi/scsi_devinfo.h
>> index 5d14adae21c7..ec12dbaff0e8 100644
>> --- a/include/scsi/scsi_devinfo.h
>> +++ b/include/scsi/scsi_devinfo.h
>> @@ -32,7 +32,8 @@
>> #define BLIST_IGN_MEDIA_CHANGE ((__force blist_flags_t)(1ULL << 11))
>> /* do not do automatic start on add */
>> #define BLIST_NOSTARTONADD ((__force blist_flags_t)(1ULL << 12))
>> -#define __BLIST_UNUSED_13 ((__force blist_flags_t)(1ULL << 13))
>> +/* do not ask for VPD page size first on some broken targets */
>> +#define BLIST_NO_ASK_VPD_SIZE ((__force blist_flags_t)(1ULL << 13))
>> #define __BLIST_UNUSED_14 ((__force blist_flags_t)(1ULL << 14))
>> #define __BLIST_UNUSED_15 ((__force blist_flags_t)(1ULL << 15))
>> #define __BLIST_UNUSED_16 ((__force blist_flags_t)(1ULL << 16))
>> @@ -74,8 +75,7 @@
>> #define __BLIST_HIGH_UNUSED (~(__BLIST_LAST_USED | \
>>       (__force blist_flags_t) \
>>       ((__force __u64)__BLIST_LAST_USED - 1ULL)))
>> -#define __BLIST_UNUSED_MASK (__BLIST_UNUSED_13 | \
>> -     __BLIST_UNUSED_14 | \
>> +#define __BLIST_UNUSED_MASK (__BLIST_UNUSED_14 | \
>>     __BLIST_UNUSED_15 | \
>>     __BLIST_UNUSED_16 | \
>>     __BLIST_UNUSED_24 | \