linux-kernel - [PATCH v2 15/24] dyndbg: extend ddebug_parse_flags to accept optional leading filter-flags

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Date:   Sat, 13 Jun 2020 09:57:29 -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>,
        Jonathan Corbet <corbet@....net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Will Deacon <will@...nel.org>, Petr Mladek <pmladek@...e.com>,
        Orson Zhai <orson.zhai@...soc.com>, linux-doc@...r.kernel.org
Subject: [PATCH v2 15/24] dyndbg: extend ddebug_parse_flags to accept optional leading filter-flags

change ddebug_parse_flags to accept optional filterflags before OP.
this now sets the parameter added in ~1
---
 .../admin-guide/dynamic-debug-howto.rst       | 18 +++++++----
 lib/dynamic_debug.c                           | 30 ++++++++++---------
 2 files changed, 28 insertions(+), 20 deletions(-)

diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index 6c04aea8f4cd..4f343e6036f5 100644
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -217,13 +217,19 @@ line
 	line -1605          // the 1605 lines from line 1 to line 1605
 	line 1600-          // all lines from line 1600 to the end of the file
 
-The flags specification comprises a change operation followed
-by one or more flag characters.  The change operation is one
-of the characters::
+Flags Specification::
 
-  -    remove the given flags
-  +    add the given flags
-  =    set the flags to the given flags
+  flagspec	::= filterflags? OP modflags
+  filterflags	::= flagset
+  modflags	::= flagset
+  flagset	::= ([pfmltu_] | [PFMLTU_])+	# also cant have pP etc
+  OP		::= [-+=]
+
+OP: modify callsites per following flagset::
+
+  -    remove the following flags
+  +    add the following flags
+  =    set the flags to the following flags
 
 The flags are::
 
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 0f393a930fdc..40436270d38a 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -441,34 +441,36 @@ static int ddebug_read_flags(const char *str, struct flagsettings *f)
 }
 
 /*
- * Parse `str' as a flags specification, format [-+=][p]+.
- * Sets up *maskp and *flagsp to be used when changing the
- * flags fields of matched _ddebug's.  Returns 0 on success
- * or <0 on error.
+ * Parse `str' as a flags-spec, ie: [pfmlt_]*[-+=][pfmlt_]+
+ * Fills flagsettings provided.  Returns 0 on success or <0 on error.
  */
-
 static int ddebug_parse_flags(const char *str,
 			      struct flagsettings *mods,
 			      struct flagsettings *filter)
 {
 	int op;
+	char *opp = strpbrk(str, "-+=");
 
-	switch (*str) {
-	case '+':
-	case '-':
-	case '=':
-		op = *str++;
-		break;
-	default:
-		pr_err("bad flag-op %c, at start of %s\n", *str, str);
+	if (!opp) {
+		pr_err("no OP given in %s\n", str);
 		return -EINVAL;
 	}
+	op = *opp;
 	vpr_info("op='%c'\n", op);
 
+	if (opp != str) {
+		/* filterflags precedes OP, grab it */
+		*opp++ = '\0';
+		if (ddebug_read_flags(str, filter))
+			return -EINVAL;
+		str = opp;
+	} else
+		str++;
+
 	if (ddebug_read_flags(str, mods))
 		return -EINVAL;
 
-	/* calculate final flags, mask based upon op */
+	/* calculate final mods: flags, mask based upon op */
 	switch (op) {
 	case '=':
 		mods->mask = 0;
-- 
2.26.2