linux-kernel - [PATCH v2 12/24] dyndbg: refactor ddebug_read_flags out of ddebug_parse

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Date:   Sat, 13 Jun 2020 09:57:26 -0600
From:   Jim Cromie <jim.cromie@...il.com>
To:     jbaron@...mai.com, linux-kernel@...r.kernel.org,
        akpm@...uxfoundation.org, gregkh@...uxfoundation.org
Cc:     linux@...musvillemoes.dk, Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH v2 12/24] dyndbg: refactor ddebug_read_flags out of ddebug_parse_flags

Currently, ddebug_parse_flags accepts [+-=][pflmt_]+ as flag-spec
strings.  If we allow [pflmt_]*[+-=][pflmt_]+ instead, the (new) 1st
flagset can be used as a filter to select callsites, before applying
changes in the 2nd flagset.  1st step is to split out the flags-reader
so we can use it again.

The point of this is to allow user to compose an arbitrary set of
changes, by marking callsites with [fmlt] flags, and then to
activate that composed set in a single query.

 #> echo '=_' > control			# clear all flags
 #> echo 'module usb* +fmlt' > control	# build the marked set, repeat
 #> echo 'fmlt+p' > control		# activate
---
 lib/dynamic_debug.c | 37 +++++++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 784c075c7db9..93c627e9c094 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -414,6 +414,26 @@ static int ddebug_parse_query(char *words[], int nwords,
 	return 0;
 }
 
+static int ddebug_read_flags(const char *str, unsigned int *flags)
+{
+	int i;
+
+	for (; *str ; ++str) {
+		for (i = ARRAY_SIZE(opt_array) - 1; i >= 0; i--) {
+			if (*str == opt_array[i].opt_char) {
+				*flags |= opt_array[i].flag;
+				break;
+			}
+		}
+		if (i < 0) {
+			pr_err("unknown flag '%c' in \"%s\"\n", *str, str);
+			return -EINVAL;
+		}
+	}
+	vpr_info("flags=0x%x\n", *flags);
+	return 0;
+}
+
 /*
  * Parse `str' as a flags specification, format [-+=][p]+.
  * Sets up *maskp and *flagsp to be used when changing the
@@ -424,7 +444,7 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
 			       unsigned int *maskp)
 {
 	unsigned flags = 0;
-	int op = '=', i;
+	int op;
 
 	switch (*str) {
 	case '+':
@@ -438,19 +458,8 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
 	}
 	vpr_info("op='%c'\n", op);
 
-	for (; *str ; ++str) {
-		for (i = ARRAY_SIZE(opt_array) - 1; i >= 0; i--) {
-			if (*str == opt_array[i].opt_char) {
-				flags |= opt_array[i].flag;
-				break;
-			}
-		}
-		if (i < 0) {
-			pr_err("unknown flag '%c' in \"%s\"\n", *str, str);
-			return -EINVAL;
-		}
-	}
-	vpr_info("flags=0x%x\n", flags);
+	if (ddebug_read_flags(str, &flags))
+		return -EINVAL;
 
 	/* calculate final *flagsp, *maskp according to mask and op */
 	switch (op) {
-- 
2.26.2