[PATCH 1/2] scsi-mq: Only show the CDB if available

[Bart Van Assche <bart.vanassche@wdc.com>]

Since the next patch will make it possible that scsi_show_rq() gets
called before the CDB pointer is changed into a non-NULL value,
only show the CDB if the CDB pointer is not NULL. Additionally,
show the request timeout and SCSI command flags. This patch also
fixes a bug that was reported by Ming Lei. See also Ming Lei,
scsi_debugfs: fix crash in scsi_show_rq(), linux-scsi, 7 November
2017 (https://marc.info/?l=linux-block&m=151006655317188).

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: James E.J. Bottomley <jejb@linux.vnet.ibm.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
---
 drivers/scsi/scsi_debugfs.c | 47 ++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 42 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/scsi_debugfs.c b/drivers/scsi/scsi_debugfs.c
index 01f08c03f2c1..37ed6bb8e6ec 100644
--- a/drivers/scsi/scsi_debugfs.c
+++ b/drivers/scsi/scsi_debugfs.c
@@ -4,13 +4,50 @@
 #include <scsi/scsi_dbg.h>
 #include "scsi_debugfs.h"
 
+#define SCSI_CMD_FLAG_NAME(name) [ilog2(SCMD_##name)] = #name
+static const char *const scsi_cmd_flags[] = {
+	SCSI_CMD_FLAG_NAME(TAGGED),
+	SCSI_CMD_FLAG_NAME(UNCHECKED_ISA_DMA),
+	SCSI_CMD_FLAG_NAME(ZONE_WRITE_LOCK),
+	SCSI_CMD_FLAG_NAME(INITIALIZED),
+};
+#undef SCSI_CMD_FLAG_NAME
+
+static int scsi_flags_show(struct seq_file *m, const unsigned long flags,
+			   const char *const *flag_name, int flag_name_count)
+{
+	bool sep = false;
+	int i;
+
+	for (i = 0; i < sizeof(flags) * BITS_PER_BYTE; i++) {
+		if (!(flags & BIT(i)))
+			continue;
+		if (sep)
+			seq_puts(m, "|");
+		sep = true;
+		if (i < flag_name_count && flag_name[i])
+			seq_puts(m, flag_name[i]);
+		else
+			seq_printf(m, "%d", i);
+	}
+	return 0;
+}
+
 void scsi_show_rq(struct seq_file *m, struct request *rq)
 {
 	struct scsi_cmnd *cmd = container_of(scsi_req(rq), typeof(*cmd), req);
-	int msecs = jiffies_to_msecs(jiffies - cmd->jiffies_at_alloc);
-	char buf[80];
+	int alloc_ms = jiffies_to_msecs(jiffies - cmd->jiffies_at_alloc);
+	int timeout_ms = jiffies_to_msecs(rq->timeout);
+	const u8 *const cdb = READ_ONCE(cmd->cmnd);
+	char buf[80] = "(?)";
 
-	__scsi_format_command(buf, sizeof(buf), cmd->cmnd, cmd->cmd_len);
-	seq_printf(m, ", .cmd=%s, .retries=%d, allocated %d.%03d s ago", buf,
-		   cmd->retries, msecs / 1000, msecs % 1000);
+	if (cdb)
+		__scsi_format_command(buf, sizeof(buf), cdb, cmd->cmd_len);
+	seq_printf(m, ", .cmd=%s, .retries=%d, .result = %#x, .flags=", buf,
+		   cmd->retries, cmd->result);
+	scsi_flags_show(m, cmd->flags, scsi_cmd_flags,
+			ARRAY_SIZE(scsi_cmd_flags));
+	seq_printf(m, ", .timeout=%d.%03d, allocated %d.%03d s ago",
+		   timeout_ms / 1000, timeout_ms % 1000,
+		   alloc_ms / 1000, alloc_ms % 1000);
 }
-- 
2.15.0