linux-kernel - [PATCH v4 22/34] vsprintf: Refactor hex_string, bitmap_string_list, bitmap

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Date:   Sun, 19 Jun 2022 20:42:21 -0400
From:   Kent Overstreet <kent.overstreet@...il.com>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org, pmladek@...e.com
Cc:     Kent Overstreet <kent.overstreet@...il.com>, rostedt@...dmis.org,
        enozhatsky@...omium.org, linux@...musvillemoes.dk,
        willy@...radead.org
Subject: [PATCH v4 22/34] vsprintf: Refactor hex_string, bitmap_string_list, bitmap_string

This patch cleans up printf_spec handling: these functions only use
spec.field_width and they do not interpret it in the normal way -
instead it's a number of bits/bytes passed in to print, so these
functions are changed to take that parameter directly.

Signed-off-by: Kent Overstreet <kent.overstreet@...il.com>
---
 lib/vsprintf.c | 60 +++++++++++++++++++++++---------------------------
 1 file changed, 28 insertions(+), 32 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 7f47533ed8..fcdf187b21 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -53,6 +53,7 @@
 #include <asm/unaligned.h>
 
 #include <linux/string_helpers.h>
+#include <linux/pretty-printers.h>
 #include "kstrtox.h"
 
 /* Disable pointer hashing if requested */
@@ -1151,18 +1152,23 @@ void resource_string(struct printbuf *out, struct resource *res,
 }
 
 static noinline_for_stack
-void hex_string(struct printbuf *out, u8 *addr,
-		struct printf_spec spec, const char *fmt)
+void hex_string(struct printbuf *out, const u8 *addr,
+		int len, const char *fmt)
 {
-	int i, len = 1;		/* if we pass '%ph[CDN]', field width remains
-				   negative value, fallback to the default */
 	char separator;
 
-	if (spec.field_width == 0)
-		/* nothing to print */
+	/* nothing to print */
+	if (len == 0)
 		return;
 
-	if (check_pointer_spec(out, addr, spec))
+	/* if we pass '%ph[CDN]', field width remains
+	   negative value, fallback to the default */
+	if (len < 0)
+		len = 1;
+
+	len = min(len, 64);
+
+	if (check_pointer(out, addr))
 		return;
 
 	switch (fmt[1]) {
@@ -1180,34 +1186,21 @@ void hex_string(struct printbuf *out, u8 *addr,
 		break;
 	}
 
-	if (spec.field_width > 0)
-		len = min_t(int, spec.field_width, 64);
-
-	for (i = 0; i < len; ++i) {
-		__prt_char(out, hex_asc_hi(addr[i]));
-		__prt_char(out, hex_asc_lo(addr[i]));
-
-		if (separator && i != len - 1)
-			__prt_char(out, separator);
-	}
-
-	printbuf_nul_terminate(out);
+	prt_hex_bytes(out, addr, len, 1, separator);
 }
 
 static noinline_for_stack
-void bitmap_string(struct printbuf *out, unsigned long *bitmap,
-		   struct printf_spec spec, const char *fmt)
+void bitmap_string(struct printbuf *out, unsigned long *bitmap, int nr_bits)
 {
+	struct printf_spec spec = { .flags = SMALL | ZEROPAD, .base = 16 };
 	const int CHUNKSZ = 32;
-	int nr_bits = max_t(int, spec.field_width, 0);
 	int i, chunksz;
 	bool first = true;
 
-	if (check_pointer_spec(out, bitmap, spec))
-		return;
+	nr_bits = max(nr_bits, 0);
 
-	/* reused to print numbers */
-	spec = (struct printf_spec){ .flags = SMALL | ZEROPAD, .base = 16 };
+	if (check_pointer(out, bitmap))
+		return;
 
 	chunksz = nr_bits & (CHUNKSZ - 1);
 	if (chunksz == 0)
@@ -1236,13 +1229,14 @@ void bitmap_string(struct printbuf *out, unsigned long *bitmap,
 
 static noinline_for_stack
 void bitmap_list_string(struct printbuf *out, unsigned long *bitmap,
-			struct printf_spec spec, const char *fmt)
+			int nr_bits)
 {
-	int nr_bits = max_t(int, spec.field_width, 0);
 	bool first = true;
 	int rbot, rtop;
 
-	if (check_pointer_spec(out, bitmap, spec))
+	nr_bits = max(nr_bits, 0);
+
+	if (check_pointer(out, bitmap))
 		return ;
 
 	for_each_set_bitrange(rbot, rtop, bitmap, nr_bits) {
@@ -2257,13 +2251,15 @@ void pointer(struct printbuf *out, const char *fmt,
 		resource_string(out, ptr, fmt[0] == 'R');
 		return do_width_precision(out, prev_pos, spec);
 	case 'h':
-		return hex_string(out, ptr, spec, fmt);
+		/* Uses field_width but _not_ as field size */
+		return hex_string(out, ptr, spec.field_width, fmt);
 	case 'b':
+		/* Uses field_width but _not_ as field size */
 		switch (fmt[1]) {
 		case 'l':
-			return bitmap_list_string(out, ptr, spec, fmt);
+			return bitmap_list_string(out, ptr, spec.field_width);
 		default:
-			return bitmap_string(out, ptr, spec, fmt);
+			return bitmap_string(out, ptr, spec.field_width);
 		}
 	case 'M':			/* Colon separated: 00:01:02:03:04:05 */
 	case 'm':			/* Contiguous: 000102030405 */
-- 
2.36.1