[PATCH v11 02/34] scsi: Allow passthrough to override what errors to retry

Mike Christie
2023-09-05T23:21:30Z

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>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
drivers/scsi/scsi_error.c | 80 +++++++++++++++++++++++++++++++++++++++
drivers/scsi/scsi_lib.c | 10 +++++
include/scsi/scsi_cmnd.h | 35 +++++++++++++++++
3 files changed, 125 insertions(+)

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 7c3eccbdd39f..d2fb28212880 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -1872,6 +1872,80 @@ bool scsi_noretry_cmd(struct scsi_cmnd *scmd)
return false;
}

+/**
+ * scsi_check_passthrough - Determine if passthrough scsi_cmnd needs a retry.
+ * @scmd: scsi_cmnd to check.
+ *
+ * Return value:
+ * SCSI_RETURN_NOT_HANDLED - if the caller should examine the command
+ * status because the passthrough user wanted the default error processing.
+ * SUCCESS, FAILED or NEEDS_RETRY - if this function has determined the
+ * command should be completed, go through the error handler due to
+ * missing sense or should be retried.
+ */
+static enum scsi_disposition scsi_check_passthrough(struct scsi_cmnd *scmd)
+{
+ struct scsi_failure *failure;
+ struct scsi_sense_hdr sshdr;
+ enum scsi_disposition ret;
+ enum sam_status status;
+
+ if (!scmd->failures)
+ return SCSI_RETURN_NOT_HANDLED;
+
+ for (failure = scmd->failures; failure->result; failure++) {
+ if (failure->result == SCMD_FAILURE_RESULT_ANY)
+ goto maybe_retry;
+
+ if (host_byte(scmd->result) &&
+ host_byte(scmd->result) == host_byte(failure->result))
+ goto maybe_retry;
+
+ status = status_byte(scmd->result);
+ if (!status)
+ continue;
+
+ if (failure->result == SCMD_FAILURE_STAT_ANY &&
+ !scsi_status_is_good(scmd->result))
+ goto maybe_retry;
+
+ if (status != status_byte(failure->result))
+ continue;
+
+ if (status_byte(failure->result) != 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.
@@ -1900,6 +1974,12 @@ enum scsi_disposition scsi_decide_disposition(struct scsi_cmnd *scmd)
return SUCCESS;
}

+ if (scmd->result && 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 ca5eb058d5c7..7c3e18663c64 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -184,6 +184,15 @@ void scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
__scsi_queue_insert(cmd, reason, true);
}

+void scsi_reset_failures(struct scsi_failure *failures)
+{
+ struct scsi_failure *failure;
+
+ for (failure = failures; failure->result; failure++)
+ failure->retries = 0;
+}
+EXPORT_SYMBOL_GPL(scsi_reset_failures);
+
/**
* scsi_execute_cmd - insert request and wait for the result
* @sdev: scsi_device
@@ -1129,6 +1138,7 @@ static void scsi_initialize_rq(struct request *rq)
init_rcu_head(&cmd->rcu);
cmd->jiffies_at_alloc = jiffies;
cmd->retries = 0;
+ cmd->failures = NULL;
}

struct request *scsi_alloc_request(struct request_queue *q, blk_opf_t opf,
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 526def14e7fb..0dc937511f2b 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -71,6 +71,38 @@ enum scsi_cmnd_submitter {
SUBMITTED_BY_SCSI_RESET_IOCTL = 2,
} __packed;

+/*
+ * scsi_execute_cmd users can set scsi_failure.result to have
+ * scsi_check_passthrough fail/retry a command. scsi_failure.result can be a
+ * specific host byte or message code, or SCMD_FAILURE_RESULT_ANY can be used
+ * to match any host or message code.
+ */
+#define SCMD_FAILURE_RESULT_ANY 0x7fffffff
+/*
+ * Set scsi_failure.result to SCMD_FAILURE_STAT_ANY to fail/retry any failure
+ * scsi_status_is_good returns false for.
+ */
+#define SCMD_FAILURE_STAT_ANY 0xff
+/*
+ * The following can be set to the scsi_failure sense, asc and ascq fields to
+ * match on any sense, ASC, or ASCQ value.
+ */
+#define SCMD_FAILURE_SENSE_ANY 0xff
+#define SCMD_FAILURE_ASC_ANY 0xff
+#define SCMD_FAILURE_ASCQ_ANY 0xff
+/* Always retry a matching failure. */
+#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 */
@@ -91,6 +123,8 @@ 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;
@@ -394,5 +428,6 @@ extern void scsi_build_sense(struct scsi_cmnd *scmd, int desc,

struct request *scsi_alloc_request(struct request_queue *q, blk_opf_t opf,
blk_mq_req_flags_t flags);
+void scsi_reset_failures(struct scsi_failure *failures);

#endif /* _SCSI_SCSI_CMND_H */
--
2.34.1