staging: unisys: visorbus: convert client_bus_info sysfs to debugfs

Previously, the sysfs entry (assuming traditional sysfs mountpoint):

    /sys/bus/visorbus/devices/visorbus<n>/client_bus_info

violated kernel conventions by printing more than one item.  This along
with the fact that the data emitted was diagnostic data (intended to
shadow the client driver info provided via s-Par livedumps) made it a
logical candidate for debugfs.  So this patch moves this sysfs entry to
debugfs as (assuming traditional debugfs mountpoint):

    /sys/kernel/debug/visorbus/visorbus<n>/client_bus_info

Data for this debugfs is emitted using the preferred seq_file interface,
which allowed a vastly-simplified version of vbuschannel_print_devinfo()
to format the individual output components.

Functionality was verified as follows:

  [root@sparguest visorbus]# mount | grep debug
  debugfs on /sys/kernel/debug type debugfs (rw)
  [root@sparguest visorbus]# pwd
  /sys/kernel/debug/visorbus
  [root@sparguest visorbus]# l visorbus1/
  total 0
  drwxr-xr-x 2 root root 0 Sep 28 16:36 .
  drwxr-xr-x 4 root root 0 Sep 28 16:36 ..
  -r--r----- 1 root root 0 Sep 28 16:36 client_bus_info
  [root@sparguest visorbus]# l visorbus2
  total 0
  drwxr-xr-x 2 root root 0 Sep 28 16:36 .
  drwxr-xr-x 4 root root 0 Sep 28 16:36 ..
  -r--r----- 1 root root 0 Sep 28 16:36 client_bus_info
  [root@sparguest visorbus]# cat visorbus1/client_bus_info
  Client device / client driver info for s-Par Console partition (vbus #1):
     chipset          visorchipset     kernel ver. 4.8.0-rc6-ARCH+
     clientbus        visorbus         kernel ver. 4.8.0-rc6-ARCH+
  [2]keyboard         visorinput       kernel ver. 4.8.0-rc6-ARCH+
  [3]mouse            visorinput       kernel ver. 4.8.0-rc6-ARCH+
  [root@sparguest visorbus]# cat visorbus2/client_bus_info
  Client device / client driver info for s-Par IOVM partition (vbus #2):
     chipset          visorchipset     kernel ver. 4.8.0-rc6-ARCH+
     clientbus        visorbus         kernel ver. 4.8.0-rc6-ARCH+
  [0]ultravnic        visornic         kernel ver. 4.8.0-rc6-ARCH+
  [1]ultravnic        visornic         kernel ver. 4.8.0-rc6-ARCH+
  [2]sparvhba         visorhba         kernel ver. 4.8.0-rc6-ARCH+

Signed-off-by: Tim Sell <Timothy.Sell@unisys.com>
Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 27 insertions, 187 deletions

diff --git a/drivers/staging/unisys/visorbus/vbuschannel.h b/drivers/staging/unisys/visorbus/vbuschannel.h
index e979175..2409b15 100644
--- a/drivers/staging/unisys/visorbus/vbuschannel.h
+++ b/drivers/staging/unisys/visorbus/vbuschannel.h
@@ -23,6 +23,7 @@
  *  the client devices and client drivers for the server end to see.
  */
 #include <linux/uuid.h>
+#include <linux/ctype.h>
 #include "channel.h"
 
 /* {193b331b-c58f-11da-95a9-00e08161165f} */
@@ -72,199 +73,38 @@ struct ultra_vbus_deviceinfo {
 };
 
 /**
- * vbuschannel_sanitize_buffer() - remove non-printable chars from buffer
- * @p: destination buffer where chars are written to
- * @remain: number of bytes that can be written starting at #p
- * @src: pointer to source buffer
- * @srcmax: number of valid characters at #src
- *
- * Reads chars from the buffer at @src for @srcmax bytes, and writes to
- * the buffer at @p, which is @remain bytes long, ensuring never to
- * overflow the buffer at @p, using the following rules:
- * - printable characters are simply copied from the buffer at @src to the
- *   buffer at @p
- * - intervening streaks of non-printable characters in the buffer at @src
- *   are replaced with a single space in the buffer at @p
- * Note that we pay no attention to '\0'-termination.
- *
- * Pass @p == NULL and @remain == 0 for this special behavior -- In this
- * case, we simply return the number of bytes that WOULD HAVE been written
- * to a buffer at @p, had it been infinitely big.
- *
- * Return: the number of bytes written to @p (or WOULD HAVE been written to
- *         @p, as described in the previous paragraph)
- */
-static inline int
-vbuschannel_sanitize_buffer(char *p, int remain, char *src, int srcmax)
-{
-	int chars = 0;
-	int nonprintable_streak = 0;
-
-	while (srcmax > 0) {
-		if ((*src >= ' ') && (*src < 0x7f)) {
-			if (nonprintable_streak) {
-				if (remain > 0) {
-					*p = ' ';
-					p++;
-					remain--;
-					chars++;
-				} else if (!p) {
-					chars++;
-				}
-				nonprintable_streak = 0;
-			}
-			if (remain > 0) {
-				*p = *src;
-				p++;
-				remain--;
-				chars++;
-			} else if (!p) {
-				chars++;
-			}
-		} else {
-			nonprintable_streak = 1;
-		}
-		src++;
-		srcmax--;
-	}
-	return chars;
-}
-
-#define VBUSCHANNEL_ADDACHAR(ch, p, remain, chars) \
-	do {					   \
-		if (remain <= 0)		   \
-			break;			   \
-		*p = ch;			   \
-		p++;  chars++;  remain--;	   \
-	} while (0)
-
-/**
- * vbuschannel_itoa() - convert non-negative int to string
- * @p: destination string
- * @remain: max number of bytes that can be written to @p
- * @num: input int to convert
- *
- * Converts the non-negative value at @num to an ascii decimal string
- * at @p, writing at most @remain bytes.  Note there is NO '\0' termination
- * written to @p.
- *
- * Return: number of bytes written to @p
- *
- */
-static inline int
-vbuschannel_itoa(char *p, int remain, int num)
-{
-	int digits = 0;
-	char s[32];
-	int i;
-
-	if (num == 0) {
-		/* '0' is a special case */
-		if (remain <= 0)
-			return 0;
-		*p = '0';
-		return 1;
-	}
-	/* form a backwards decimal ascii string in <s> */
-	while (num > 0) {
-		if (digits >= (int)sizeof(s))
-			return 0;
-		s[digits++] = (num % 10) + '0';
-		num = num / 10;
-	}
-	if (remain < digits) {
-		/* not enough room left at <p> to hold number, so fill with
-		 * '?'
-		 */
-		for (i = 0; i < remain; i++, p++)
-			*p = '?';
-		return remain;
-	}
-	/* plug in the decimal ascii string representing the number, by */
-	/* reversing the string we just built in <s> */
-	i = digits;
-	while (i > 0) {
-		i--;
-		*p = s[i];
-		p++;
-	}
-	return digits;
-}
-
-/**
- * vbuschannel_devinfo_to_string() - format a struct ultra_vbus_deviceinfo
- *                                   to a printable string
+ * vbuschannel_print_devinfo() - format a struct ultra_vbus_deviceinfo
+ *                               and write it to a seq_file
  * @devinfo: the struct ultra_vbus_deviceinfo to format
- * @p: destination string area
- * @remain: size of destination string area in bytes
+ * @seq: seq_file to write to
  * @devix: the device index to be included in the output data, or -1 if no
  *         device index is to be included
  *
- * Reads @devInfo, and converts its contents to a printable string at @p,
- * writing at most @remain bytes. Note there is NO '\0' termination
- * written to @p.
- *
- * Return: number of bytes written to @p
+ * Reads @devInfo, and writes it in human-readable notation to @seq.
  */
-static inline int
-vbuschannel_devinfo_to_string(struct ultra_vbus_deviceinfo *devinfo,
-			      char *p, int remain, int devix)
+static inline void
+vbuschannel_print_devinfo(struct ultra_vbus_deviceinfo *devinfo,
+			  struct seq_file *seq, int devix)
 {
-	char *psrc;
-	int nsrc, x, i, pad;
-	int chars = 0;
-
-	psrc = &devinfo->devtype[0];
-	nsrc = sizeof(devinfo->devtype);
-	if (vbuschannel_sanitize_buffer(NULL, 0, psrc, nsrc) <= 0)
-		return 0;
-
-	/* emit device index */
-	if (devix >= 0) {
-		VBUSCHANNEL_ADDACHAR('[', p, remain, chars);
-		x = vbuschannel_itoa(p, remain, devix);
-		p += x;
-		remain -= x;
-		chars += x;
-		VBUSCHANNEL_ADDACHAR(']', p, remain, chars);
-	} else {
-		VBUSCHANNEL_ADDACHAR(' ', p, remain, chars);
-		VBUSCHANNEL_ADDACHAR(' ', p, remain, chars);
-		VBUSCHANNEL_ADDACHAR(' ', p, remain, chars);
-	}
-
-	/* emit device type */
-	x = vbuschannel_sanitize_buffer(p, remain, psrc, nsrc);
-	p += x;
-	remain -= x;
-	chars += x;
-	pad = 15 - x;		/* pad device type to be exactly 15 chars */
-	for (i = 0; i < pad; i++)
-		VBUSCHANNEL_ADDACHAR(' ', p, remain, chars);
-	VBUSCHANNEL_ADDACHAR(' ', p, remain, chars);
-
-	/* emit driver name */
-	psrc = &devinfo->drvname[0];
-	nsrc = sizeof(devinfo->drvname);
-	x = vbuschannel_sanitize_buffer(p, remain, psrc, nsrc);
-	p += x;
-	remain -= x;
-	chars += x;
-	pad = 15 - x;		/* pad driver name to be exactly 15 chars */
-	for (i = 0; i < pad; i++)
-		VBUSCHANNEL_ADDACHAR(' ', p, remain, chars);
-	VBUSCHANNEL_ADDACHAR(' ', p, remain, chars);
-
-	/* emit strings */
-	psrc = &devinfo->infostrs[0];
-	nsrc = sizeof(devinfo->infostrs);
-	x = vbuschannel_sanitize_buffer(p, remain, psrc, nsrc);
-	p += x;
-	remain -= x;
-	chars += x;
-	VBUSCHANNEL_ADDACHAR('\n', p, remain, chars);
-
-	return chars;
+	if (!isprint(devinfo->devtype[0]))
+		return; /* uninitialized vbus device entry */
+
+	if (devix >= 0)
+		seq_printf(seq, "[%d]", devix);
+	else
+		/* vbus device entry is for bus or chipset */
+		seq_puts(seq, "   ");
+
+	/*
+	 * Note: because the s-Par back-end is free to scribble in this area,
+	 * we never assume '\0'-termination.
+	 */
+	seq_printf(seq, "%-*.*s ", (int)sizeof(devinfo->devtype),
+		   (int)sizeof(devinfo->devtype), devinfo->devtype);
+	seq_printf(seq, "%-*.*s ", (int)sizeof(devinfo->drvname),
+		   (int)sizeof(devinfo->drvname), devinfo->drvname);
+	seq_printf(seq, "%.*s\n", (int)sizeof(devinfo->infostrs),
+		   devinfo->infostrs);
 }
 
 struct spar_vbus_headerinfo {