[PATCH v2 02/35] scsi: Allow passthrough to override what errors to retry

Mike Christie
2022-09-29T02:54:29Z

For passthrough, we don't retry any error we get a check condition for.
This results in a lot of callers driving their own retries for those types
of errors and retrying all errors, and there has been a request to retry
specific host byte errors.

This adds the core code to allow passthrough users to specify what errors
they want scsi-ml to retry for them. We can then convert users to drop
their sense parsing and retry handling.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
drivers/scsi/scsi_error.c | 63 +++++++++++++++++++++++++++++++++++++++
drivers/scsi/scsi_lib.c | 1 +
include/scsi/scsi_cmnd.h | 26 +++++++++++++++-
3 files changed, 89 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 3f630798d1eb..4bf7b65bc63d 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -1831,6 +1831,63 @@ bool scsi_noretry_cmd(struct scsi_cmnd *scmd)
return false;
}

+static enum scsi_disposition scsi_check_passthrough(struct scsi_cmnd *scmd)
+{
+ struct scsi_failure *failure;
+ struct scsi_sense_hdr sshdr;
+ enum scsi_disposition ret;
+ int i = 0;
+
+ if (!scmd->result || !scmd->failures)
+ return SCSI_RETURN_NOT_HANDLED;
+
+ while (1) {
+ failure = &scmd->failures[i++];
+ if (!failure->result)
+ break;
+
+ if (failure->result == SCMD_FAILURE_ANY)
+ goto maybe_retry;
+
+ if (host_byte(scmd->result) & host_byte(failure->result)) {
+ goto maybe_retry;
+ } else if (get_status_byte(scmd) &
+ __get_status_byte(failure->result)) {
+ if (get_status_byte(scmd) != SAM_STAT_CHECK_CONDITION ||
+ failure->sense == SCMD_FAILURE_SENSE_ANY)
+ goto maybe_retry;
+
+ ret = scsi_start_sense_processing(scmd, &sshdr);
+ if (ret == NEEDS_RETRY)
+ goto maybe_retry;
+ else if (ret != SUCCESS)
+ return ret;
+
+ if (failure->sense != sshdr.sense_key)
+ continue;
+
+ if (failure->asc == SCMD_FAILURE_ASC_ANY)
+ goto maybe_retry;
+
+ if (failure->asc != sshdr.asc)
+ continue;
+
+ if (failure->ascq == SCMD_FAILURE_ASCQ_ANY ||
+ failure->ascq == sshdr.ascq)
+ goto maybe_retry;
+ }
+ }
+
+ return SCSI_RETURN_NOT_HANDLED;
+
+maybe_retry:
+ if (failure->allowed == SCMD_FAILURE_NO_LIMIT ||
+ ++failure->retries <= failure->allowed)
+ return NEEDS_RETRY;
+
+ return SUCCESS;
+}
+
/**
* scsi_decide_disposition - Disposition a cmd on return from LLD.
* @scmd: SCSI cmd to examine.
@@ -1859,6 +1916,12 @@ enum scsi_disposition scsi_decide_disposition(struct scsi_cmnd *scmd)
return SUCCESS;
}

+ if (blk_rq_is_passthrough(scsi_cmd_to_rq(scmd))) {
+ rtn = scsi_check_passthrough(scmd);
+ if (rtn != SCSI_RETURN_NOT_HANDLED)
+ return rtn;
+ }
+
/*
* first check the host byte, to see if there is anything in there
* that would indicate what we need to do.
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 497efc0da259..56aefe38d69b 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1608,6 +1608,7 @@ static blk_status_t scsi_prepare_cmd(struct request *req)

/* Usually overridden by the ULP */
cmd->allowed = 0;
+ cmd->failures = NULL;
memset(cmd->cmnd, 0, sizeof(cmd->cmnd));
return scsi_cmd_to_driver(cmd)->init_command(cmd);
}
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index bac55decf900..9fb85932d5b9 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -65,6 +65,23 @@ enum scsi_cmnd_submitter {
SUBMITTED_BY_SCSI_RESET_IOCTL = 2,
} __packed;

+#define SCMD_FAILURE_NONE 0
+#define SCMD_FAILURE_ANY -1
+#define SCMD_FAILURE_SENSE_ANY 0xff
+#define SCMD_FAILURE_ASC_ANY 0xff
+#define SCMD_FAILURE_ASCQ_ANY 0xff
+#define SCMD_FAILURE_NO_LIMIT -1
+
+struct scsi_failure {
+ int result;
+ u8 sense;
+ u8 asc;
+ u8 ascq;
+
+ s8 allowed;
+ s8 retries;
+};
+
struct scsi_cmnd {
struct scsi_device *device;
struct list_head eh_entry; /* entry for the host eh_abort_list/eh_cmd_q */
@@ -85,6 +102,8 @@ struct scsi_cmnd {

int retries;
int allowed;
+ /* optional array of failures that passthrough users want retried */
+ struct scsi_failure *failures;

unsigned char prot_op;
unsigned char prot_type;
@@ -330,9 +349,14 @@ static inline void set_status_byte(struct scsi_cmnd *cmd, char status)
cmd->result = (cmd->result & 0xffffff00) | status;
}

+static inline u8 __get_status_byte(int result)
+{
+ return result & 0xff;
+}
+
static inline u8 get_status_byte(struct scsi_cmnd *cmd)
{
- return cmd->result & 0xff;
+ return __get_status_byte(cmd->result);
}

static inline void set_host_byte(struct scsi_cmnd *cmd, char status)
--
2.25.1