[PATCH] sense data helpers lk 2.6.11-rc1-bk1

   - add sense data helper functions:
   - scsi_sense_desc_find() to find a given
     sense descriptor (e.g. type 0 -> information)
   - scsi_get_sense_info_fld() to get the information
     field from fixed or descriptor sense data

Kai Makisara proposed the "find" function. For
example, it will help the st driver find the Filemark,
EOM and ILI flags which have been placed in the
"stream commands" sense data descriptor.
Signed-off-by: Douglas Gilbert <dougg@torque.net>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/scsi_error.c

@@ -1948,3 +1948,96 @@ int scsi_command_normalize_sense(struct scsi_cmnd *cmd,
 			sizeof(cmd->sense_buffer), sshdr);
 }
 EXPORT_SYMBOL(scsi_command_normalize_sense);
+
+/**
+ * scsi_sense_desc_find - search for a given descriptor type in
+ *			descriptor sense data format.
+ *
+ * @sense_buffer:	byte array of descriptor format sense data
+ * @sb_len:		number of valid bytes in sense_buffer
+ * @desc_type:		value of descriptor type to find
+ *			(e.g. 0 -> information)
+ *
+ * Notes:
+ *	only valid when sense data is in descriptor format
+ *
+ * Return value:
+ *	pointer to start of (first) descriptor if found else NULL
+ **/
+const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
+				int desc_type)
+{
+	int add_sen_len, add_len, desc_len, k;
+	const u8 * descp;
+
+	if ((sb_len < 8) || (0 == (add_sen_len = sense_buffer[7])))
+		return NULL;
+	if ((sense_buffer[0] < 0x72) || (sense_buffer[0] > 0x73))
+		return NULL;
+	add_sen_len = (add_sen_len < (sb_len - 8)) ?
+			add_sen_len : (sb_len - 8);
+	descp = &sense_buffer[8];
+	for (desc_len = 0, k = 0; k < add_sen_len; k += desc_len) {
+		descp += desc_len;
+		add_len = (k < (add_sen_len - 1)) ? descp[1]: -1;
+		desc_len = add_len + 2;
+		if (descp[0] == desc_type)
+			return descp;
+		if (add_len < 0) // short descriptor ??
+			break;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(scsi_sense_desc_find);
+
+/**
+ * scsi_get_sense_info_fld - attempts to get information field from
+ *			sense data (either fixed or descriptor format)
+ *
+ * @sense_buffer:	byte array of sense data
+ * @sb_len:		number of valid bytes in sense_buffer
+ * @info_out:		pointer to 64 integer where 8 or 4 byte information
+ *			field will be placed if found.
+ *
+ * Return value:
+ *	1 if information field found, 0 if not found.
+ **/
+int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
+			    u64 * info_out)
+{
+	int j;
+	const u8 * ucp;
+	u64 ull;
+
+	if (sb_len < 7)
+		return 0;
+	switch (sense_buffer[0] & 0x7f) {
+	case 0x70:
+	case 0x71:
+		if (sense_buffer[0] & 0x80) {
+			*info_out = (sense_buffer[3] << 24) +
+				    (sense_buffer[4] << 16) +
+				    (sense_buffer[5] << 8) + sense_buffer[6];
+			return 1;
+		} else
+			return 0;
+	case 0x72:
+	case 0x73:
+		ucp = scsi_sense_desc_find(sense_buffer, sb_len,
+					   0 /* info desc */);
+		if (ucp && (0xa == ucp[1])) {
+			ull = 0;
+			for (j = 0; j < 8; ++j) {
+				if (j > 0)
+					ull <<= 8;
+				ull |= ucp[4 + j];
+			}
+			*info_out = ull;
+			return 1;
+		} else
+			return 0;
+	default:
+		return 0;
+	}
+}
+EXPORT_SYMBOL(scsi_get_sense_info_fld);

include/scsi/scsi_eh.h

@@ -44,6 +44,12 @@ static inline int scsi_sense_is_deferred(struct scsi_sense_hdr *sshdr)
 {
 	return ((sshdr->response_code >= 0x70) && (sshdr->response_code & 1));
 }
+
+extern const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
+				       int desc_type);
+
+extern int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
+				   u64 * info_out);
  
 /*
  * Reset request from external source