From 65ca846a53149a1a72cd8d02e7b2e73dd545b834 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Wed, 22 Jan 2020 19:56:34 -0800 Subject: [PATCH] scsi: core: Introduce {init,exit}_cmd_priv() The current behavior of the SCSI core is to clear driver-private data before preparing a request for submission to the SCSI LLD. Make it possible for SCSI LLDs to disable clearing of driver-private data. These hooks will be used by a later patch, namely "scsi: ufs: Let the SCSI core allocate per-command UFS data". Link: https://lore.kernel.org/r/20200123035637.21848-2-bvanassche@acm.org Cc: Tomas Winkler Cc: Stanley Chu Cc: Bean Huo Cc: Avri Altman Cc: Can Guo Cc: Ming Lei Cc: Johannes Thumshirn Cc: Hannes Reinecke Cc: Christoph Hellwig Signed-off-by: Bart Van Assche Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_lib.c | 29 +++++++++++++++++++++++------ include/scsi/scsi_host.h | 3 +++ 2 files changed, 26 insertions(+), 6 deletions(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 258a428a0a3f..9f201194c46a 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1097,7 +1097,7 @@ static void scsi_cleanup_rq(struct request *rq) } } -/* Called after a request has been started. */ +/* Called before a request is prepared. See also scsi_mq_prep_fn(). */ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd) { void *buf = cmd->sense_buffer; @@ -1105,7 +1105,7 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd) struct request *rq = blk_mq_rq_from_pdu(cmd); unsigned int flags = cmd->flags & SCMD_PRESERVED_FLAGS; unsigned long jiffies_at_alloc; - int retries; + int retries, to_clear; bool in_flight; if (!blk_rq_is_scsi(rq) && !(flags & SCMD_INITIALIZED)) { @@ -1116,9 +1116,15 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd) jiffies_at_alloc = cmd->jiffies_at_alloc; retries = cmd->retries; in_flight = test_bit(SCMD_STATE_INFLIGHT, &cmd->state); - /* zero out the cmd, except for the embedded scsi_request */ - memset((char *)cmd + sizeof(cmd->req), 0, - sizeof(*cmd) - sizeof(cmd->req) + dev->host->hostt->cmd_size); + /* + * Zero out the cmd, except for the embedded scsi_request. Only clear + * the driver-private command data if the LLD does not supply a + * function to initialize that data. + */ + to_clear = sizeof(*cmd) - sizeof(cmd->req); + if (!dev->host->hostt->init_cmd_priv) + to_clear += dev->host->hostt->cmd_size; + memset((char *)cmd + sizeof(cmd->req), 0, to_clear); cmd->device = dev; cmd->sense_buffer = buf; @@ -1711,6 +1717,7 @@ static int scsi_mq_init_request(struct blk_mq_tag_set *set, struct request *rq, const bool unchecked_isa_dma = shost->unchecked_isa_dma; struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq); struct scatterlist *sg; + int ret = 0; if (unchecked_isa_dma) cmd->flags |= SCMD_UNCHECKED_ISA_DMA; @@ -1726,14 +1733,24 @@ static int scsi_mq_init_request(struct blk_mq_tag_set *set, struct request *rq, cmd->prot_sdb = (void *)sg + scsi_mq_inline_sgl_size(shost); } - return 0; + if (shost->hostt->init_cmd_priv) { + ret = shost->hostt->init_cmd_priv(shost, cmd); + if (ret < 0) + scsi_free_sense_buffer(unchecked_isa_dma, + cmd->sense_buffer); + } + + return ret; } static void scsi_mq_exit_request(struct blk_mq_tag_set *set, struct request *rq, unsigned int hctx_idx) { + struct Scsi_Host *shost = set->driver_data; struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq); + if (shost->hostt->exit_cmd_priv) + shost->hostt->exit_cmd_priv(shost, cmd); scsi_free_sense_buffer(cmd->flags & SCMD_UNCHECKED_ISA_DMA, cmd->sense_buffer); } diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index 74dc7d4f2a96..7464394e7d01 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -62,6 +62,9 @@ struct scsi_host_template { void __user *arg); #endif + int (*init_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd); + int (*exit_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd); + /* * The queuecommand function is used to queue up a scsi * command block to the LLDD. When the driver finished