| Message ID | 20200703130122.111448-14-hare@suse.de (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | scsi: enable reserved commands for LLDDs | expand |
On 03/07/2020 14:01, Hannes Reinecke wrote: > Quite some drivers are using management commands internally, which > typically use the same hardware tag pool (ie they are being allocated > from the same hardware resources) as the 'normal' I/O commands. > These commands are set aside before allocating the block-mq tag bitmap, > so they'll never show up as busy in the tag map. > The block-layer, OTOH, already has 'reserved_tags' to handle precisely > this situation. > So this patch adds a new field 'nr_reserved_cmds' to the SCSI host > template to instruct the block layer to set aside a tag space for these > management commands by using reserved tags. > Apart from (a good few) comments: Reviewed-by: John Garry <john.garry@huawei.com> > Signed-off-by: Hannes Reinecke <hare@suse.de> > --- > drivers/scsi/hosts.c | 3 +++ > drivers/scsi/scsi_lib.c | 10 +++++++++- > include/scsi/scsi_host.h | 22 +++++++++++++++++++++- > 3 files changed, 33 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c > index 7ec91c3a66ca..db91b045a4ce 100644 > --- a/drivers/scsi/hosts.c > +++ b/drivers/scsi/hosts.c > @@ -466,6 +466,9 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) > if (sht->virt_boundary_mask) > shost->virt_boundary_mask = sht->virt_boundary_mask; > > + if (sht->nr_reserved_cmds) > + shost->nr_reserved_cmds = sht->nr_reserved_cmds; > + > device_initialize(&shost->shost_gendev); > dev_set_name(&shost->shost_gendev, "host%d", shost->host_no); > shost->shost_gendev.bus = &scsi_bus_type; > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index 1d5c1b9a1203..1362f4f17dfd 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -1887,7 +1887,9 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost) > else > tag_set->ops = &scsi_mq_ops_no_commit; > tag_set->nr_hw_queues = shost->nr_hw_queues ? : 1; > - tag_set->queue_depth = shost->can_queue; > + tag_set->queue_depth = > + shost->can_queue + shost->nr_reserved_cmds; I think that this can fit on a single line without exceeding 80 characters > + tag_set->reserved_tags = shost->nr_reserved_cmds; > tag_set->cmd_size = cmd_size; > tag_set->numa_node = NUMA_NO_NODE; > tag_set->flags = BLK_MQ_F_SHOULD_MERGE; > @@ -1910,6 +1912,9 @@ void scsi_mq_destroy_tags(struct Scsi_Host *shost) > * @op_flags: request allocation flags > * > * Allocates a SCSI command for internal LLDD use. > + * If 'nr_reserved_commands' is spectified by the host the again, please check spellings > + * command will be allocated from the reserved tag pool; > + * otherwise the normal tag pool will be used. > */ > struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev, > enum dma_data_direction data_direction, int op_flags) > @@ -1919,6 +1924,9 @@ struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev, > blk_mq_req_flags_t flags = 0; > unsigned int op = REQ_INTERNAL | op_flags; > > + if (sdev->host->nr_reserved_cmds) > + flags = BLK_MQ_REQ_RESERVED; Previously I mentioned that '|=' is nicer - not sure if it was missed or dismissed, so mentioning it again just in case > + > op |= (data_direction == DMA_TO_DEVICE) ? > REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN; > rq = blk_mq_alloc_request(sdev->request_queue, op, flags); > diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h > index 4919a66565d6..c4d0d26c880e 100644 > --- a/include/scsi/scsi_host.h > +++ b/include/scsi/scsi_host.h > @@ -342,10 +342,19 @@ struct scsi_host_template { > /* > * This determines if we will use a non-interrupt driven > * or an interrupt driven scheme. It is set to the maximum number > - * of simultaneous commands a single hw queue in HBA will accept. > + * of simultaneous commands a single hw queue in HBA will accept > + * excluding internal commands. > */ > int can_queue; > > + /* > + * This determines how many commands the HBA will set aside > + * for internal commands. This number will be added to > + * @can_queue to calcumate the maximum number of simultaneous check spelling of calculate > + * commands sent to the host. > + */ > + int nr_reserved_cmds; We have can_queue file in the scsi_host sysfs folder - I wonder if it is also worth adding a file for this? > + > /*
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c index 7ec91c3a66ca..db91b045a4ce 100644 --- a/drivers/scsi/hosts.c +++ b/drivers/scsi/hosts.c @@ -466,6 +466,9 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) if (sht->virt_boundary_mask) shost->virt_boundary_mask = sht->virt_boundary_mask; + if (sht->nr_reserved_cmds) + shost->nr_reserved_cmds = sht->nr_reserved_cmds; + device_initialize(&shost->shost_gendev); dev_set_name(&shost->shost_gendev, "host%d", shost->host_no); shost->shost_gendev.bus = &scsi_bus_type; diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 1d5c1b9a1203..1362f4f17dfd 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1887,7 +1887,9 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost) else tag_set->ops = &scsi_mq_ops_no_commit; tag_set->nr_hw_queues = shost->nr_hw_queues ? : 1; - tag_set->queue_depth = shost->can_queue; + tag_set->queue_depth = + shost->can_queue + shost->nr_reserved_cmds; + tag_set->reserved_tags = shost->nr_reserved_cmds; tag_set->cmd_size = cmd_size; tag_set->numa_node = NUMA_NO_NODE; tag_set->flags = BLK_MQ_F_SHOULD_MERGE; @@ -1910,6 +1912,9 @@ void scsi_mq_destroy_tags(struct Scsi_Host *shost) * @op_flags: request allocation flags * * Allocates a SCSI command for internal LLDD use. + * If 'nr_reserved_commands' is spectified by the host the + * command will be allocated from the reserved tag pool; + * otherwise the normal tag pool will be used. */ struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev, enum dma_data_direction data_direction, int op_flags) @@ -1919,6 +1924,9 @@ struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev, blk_mq_req_flags_t flags = 0; unsigned int op = REQ_INTERNAL | op_flags; + if (sdev->host->nr_reserved_cmds) + flags = BLK_MQ_REQ_RESERVED; + op |= (data_direction == DMA_TO_DEVICE) ? REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN; rq = blk_mq_alloc_request(sdev->request_queue, op, flags); diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index 4919a66565d6..c4d0d26c880e 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -342,10 +342,19 @@ struct scsi_host_template { /* * This determines if we will use a non-interrupt driven * or an interrupt driven scheme. It is set to the maximum number - * of simultaneous commands a single hw queue in HBA will accept. + * of simultaneous commands a single hw queue in HBA will accept + * excluding internal commands. */ int can_queue; + /* + * This determines how many commands the HBA will set aside + * for internal commands. This number will be added to + * @can_queue to calcumate the maximum number of simultaneous + * commands sent to the host. + */ + int nr_reserved_cmds; + /* * In many instances, especially where disconnect / reconnect are * supported, our host also has an ID on the SCSI bus. If this is @@ -590,6 +599,11 @@ struct Scsi_Host { unsigned short max_cmd_len; int this_id; + + /* + * Number of commands this host can handle at the same time. + * This excludes reserved commands as specified by nr_reserved_cmds. + */ int can_queue; short cmd_per_lun; short unsigned int sg_tablesize; @@ -606,6 +620,12 @@ struct Scsi_Host { * is nr_hw_queues * can_queue. */ unsigned nr_hw_queues; + + /* + * Number of reserved commands to allocate, if any. + */ + unsigned nr_reserved_cmds; + unsigned active_mode:2; unsigned unchecked_isa_dma:1;
Quite some drivers are using management commands internally, which typically use the same hardware tag pool (ie they are being allocated from the same hardware resources) as the 'normal' I/O commands. These commands are set aside before allocating the block-mq tag bitmap, so they'll never show up as busy in the tag map. The block-layer, OTOH, already has 'reserved_tags' to handle precisely this situation. So this patch adds a new field 'nr_reserved_cmds' to the SCSI host template to instruct the block layer to set aside a tag space for these management commands by using reserved tags. Signed-off-by: Hannes Reinecke <hare@suse.de> --- drivers/scsi/hosts.c | 3 +++ drivers/scsi/scsi_lib.c | 10 +++++++++- include/scsi/scsi_host.h | 22 +++++++++++++++++++++- 3 files changed, 33 insertions(+), 2 deletions(-)