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Subject: Re: [PATCH 3/4] scsi: hisi_sas: Make sg_tablesize consistent value
From:   Steffen Maier <maier@linux.ibm.com>
To:     John Garry <john.garry@huawei.com>, jejb@linux.vnet.ibm.com,
        martin.petersen@oracle.com
Cc:     linuxarm@huawei.com, linux-kernel@vger.kernel.org,
        linux-scsi@vger.kernel.org, Xiang Chen <chenxiang66@hisilicon.com>
References: <1542725944-244183-1-git-send-email-john.garry@huawei.com>
 <1542725944-244183-4-git-send-email-john.garry@huawei.com>
 <146f7c38-0cd7-a664-31d6-30a27b7a182b@linux.ibm.com>
Date:   Wed, 21 Nov 2018 12:08:11 +0100
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On 11/21/2018 12:02 PM, Steffen Maier wrote:
> On 11/20/2018 03:59 PM, John Garry wrote:
>> From: Xiang Chen <chenxiang66@hisilicon.com>
>>
>> Sht->sg_tablesize is set in the driver, and it will be assigned to
>> shost->sg_tablesize in SCSI mid-layer. So it is not necessary to
>> assign shost->sg_table one more time in the driver.
>>
>> In addition to the change, change each scsi_host_template.sg_tablesize
>> to HISI_SAS_SGE_PAGE_CNT instead of SG_ALL.
> 
> Might be completely irrelevant, so just as information: I once had 
> problems due to changing (reducing) SHT.sg_tablesize because block queue 
> limits of BSG devices of Scsi_Host and fc_host (not sure if you have an 
> equivalent bsg device for your transport(s)) inherit from SHT, but don't 
> update (automatically) on later updates of shost->sg_tablesize, which in 
> turn affect scsi_devices allocated after the shost update.
> Cf. 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/s390/scsi?id=5fea4291deacd80188b996d2f555fc6a1940e5d4 

Figured, your new constant seems to have the same value so no problem.

#define SG_CHUNK_SIZE	128
#define SG_ALL	SG_CHUNK_SIZE
#define HISI_SAS_SGE_PAGE_CNT SG_CHUNK_SIZE

> ("[SCSI] zfcp: block queue limits with data router")
> if you need more details.
> 
>> Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
>> Signed-off-by: John Garry <john.garry@huawei.com>
>> ---
>>   drivers/scsi/hisi_sas/hisi_sas_main.c  | 1 -
>>   drivers/scsi/hisi_sas/hisi_sas_v1_hw.c | 2 +-
>>   drivers/scsi/hisi_sas/hisi_sas_v2_hw.c | 2 +-
>>   drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 3 +--
>>   4 files changed, 3 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c 
>> b/drivers/scsi/hisi_sas/hisi_sas_main.c
>> index d13a662..cbda48e 100644
>> --- a/drivers/scsi/hisi_sas/hisi_sas_main.c
>> +++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
>> @@ -2410,7 +2410,6 @@ int hisi_sas_probe(struct platform_device *pdev,
>>       shost->max_lun = ~0;
>>       shost->max_channel = 1;
>>       shost->max_cmd_len = 16;
>> -    shost->sg_tablesize = min_t(u16, SG_ALL, HISI_SAS_SGE_PAGE_CNT);
>>       if (hisi_hba->hw->slot_index_alloc) {
>>           shost->can_queue = hisi_hba->hw->max_command_entries;
>>           shost->cmd_per_lun = hisi_hba->hw->max_command_entries;
>> diff --git a/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c 
>> b/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
>> index d24342b..2d035cc 100644
>> --- a/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
>> +++ b/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
>> @@ -1815,7 +1815,7 @@ static int hisi_sas_v1_init(struct hisi_hba 
>> *hisi_hba)
>>       .change_queue_depth    = sas_change_queue_depth,
>>       .bios_param        = sas_bios_param,
>>       .this_id        = -1,
>> -    .sg_tablesize        = SG_ALL,
>> +    .sg_tablesize        = HISI_SAS_SGE_PAGE_CNT,
>>       .max_sectors        = SCSI_DEFAULT_MAX_SECTORS,
>>       .use_clustering        = ENABLE_CLUSTERING,
>>       .eh_device_reset_handler = sas_eh_device_reset_handler,
>> diff --git a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c 
>> b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
>> index e78a97e..79e58a7 100644
>> --- a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
>> +++ b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
>> @@ -3570,7 +3570,7 @@ struct device_attribute *host_attrs_v2_hw[] = {
>>       .change_queue_depth    = sas_change_queue_depth,
>>       .bios_param        = sas_bios_param,
>>       .this_id        = -1,
>> -    .sg_tablesize        = SG_ALL,
>> +    .sg_tablesize        = HISI_SAS_SGE_PAGE_CNT,
>>       .max_sectors        = SCSI_DEFAULT_MAX_SECTORS,
>>       .use_clustering        = ENABLE_CLUSTERING,
>>       .eh_device_reset_handler = sas_eh_device_reset_handler,
>> diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c 
>> b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
>> index 7e2b020..8a08078 100644
>> --- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
>> +++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
>> @@ -2224,7 +2224,7 @@ struct device_attribute *host_attrs_v3_hw[] = {
>>       .change_queue_depth    = sas_change_queue_depth,
>>       .bios_param        = sas_bios_param,
>>       .this_id        = -1,
>> -    .sg_tablesize        = SG_ALL,
>> +    .sg_tablesize        = HISI_SAS_SGE_PAGE_CNT,
>>       .max_sectors        = SCSI_DEFAULT_MAX_SECTORS,
>>       .use_clustering        = ENABLE_CLUSTERING,
>>       .eh_device_reset_handler = sas_eh_device_reset_handler,
>> @@ -2366,7 +2366,6 @@ struct device_attribute *host_attrs_v3_hw[] = {
>>       shost->max_lun = ~0;
>>       shost->max_channel = 1;
>>       shost->max_cmd_len = 16;
>> -    shost->sg_tablesize = min_t(u16, SG_ALL, HISI_SAS_SGE_PAGE_CNT);
>>       shost->can_queue = hisi_hba->hw->max_command_entries -
>>           HISI_SAS_RESERVED_IPTT_CNT;
>>       shost->cmd_per_lun = hisi_hba->hw->max_command_entries -
>>
> 
> 


-- 
Mit freundlichen Gruessen / Kind regards
Steffen Maier

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