Re: [PATCH v2 12/30] cxlflash: Refine host/device attributes

On 09/16/2015 04:29 PM, Matthew R. Ochs wrote:

Implement the following suggestions and add two new attributes
to allow for debugging the port LUN table.

 - use scnprintf() instead of snprintf()
 - use DEVICE_ATTR_RO and DEVICE_ATTR_RW

Signed-off-by: Matthew R. Ochs <redacted>
Signed-off-by: Manoj N. Kumar <redacted>
Suggested-by: Shane Seymour <redacted>
---
 drivers/scsi/cxlflash/main.c | 180 +++++++++++++++++++++++++++++++++----------
 1 file changed, 138 insertions(+), 42 deletions(-)

 /**
- * cxlflash_show_dev_mode() - presents the current mode of the device
+ * cxlflash_show_port_lun_table() - queries and presents the port LUN table
+ * @port:	Desired port for status reporting.
+ * @afu:	AFU owning the specified port.
+ * @buf:	Buffer of length PAGE_SIZE to report back port status in ASCII.
+ *
+ * Return: The size of the ASCII string returned in @buf.
+ */
+static ssize_t cxlflash_show_port_lun_table(u32 port,
+					    struct afu *afu,
+					    char *buf)
+{
+	int i;
+	ssize_t bytes = 0;
+	__be64 __iomem *fc_port;
+
+	if (port >= NUM_FC_PORTS)
+		return 0;
+
+	fc_port = &afu->afu_map->global.fc_port[port][0];
+
+	for (i = 0; i < CXLFLASH_NUM_VLUNS; i++, buf += 22)

Rather than this bug prone hard coded 22, how about never incrementing buf and do something
similar to this:

+		bytes += scnprintf(buf, PAGE_SIZE, "%03d: %016llX\n",
+				   i, readq_be(&fc_port[i]));

		bytes += scnprintf(&buf[bytes], PAGE_SIZE, "%03d: %016llX\n",
				   i, readq_be(&fc_port[i]));

+	return bytes;
+}
+

-- 
Brian King
Power Linux I/O
IBM Linux Technology Center