kernel-doc: allow multi-line declaration purpose descriptions

Allow the short description after symbol name and dash in a kernel-doc
comment to span multiple lines, e.g. like this:

	/**
	 * unmap_mapping_range - unmap the portion of all mmaps in the
	 *	specified address_space corresponding to the specified
	 *	page range in the underlying file.
	 * @mapping: the address space containing mmaps to be unmapped.
	 * ...
	 */

The short description ends with a parameter description, an empty line
or the end of the comment block.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 19 insertions, 6 deletions

diff --git a/Documentation/kernel-doc-nano-HOWTO.txt b/Documentation/kernel-doc-nano-HOWTO.txt
index 4d04572b6549..348b9e5e28fc 100644
--- a/Documentation/kernel-doc-nano-HOWTO.txt
+++ b/Documentation/kernel-doc-nano-HOWTO.txt
@@ -66,7 +66,9 @@ Example kernel-doc function comment:
  * The longer description can have multiple paragraphs.
  */
 
-The first line, with the short description, must be on a single line.
+The short description following the subject can span multiple lines
+and ends with an @argument description, an empty line or the end of
+the comment block.
 
 The @argument descriptions must begin on the very next line following
 this opening short function description line, with no intervening
diff --git a/scripts/kernel-doc b/scripts/kernel-doc
index b52d340d759d..ea9f8a58678f 100755
--- a/scripts/kernel-doc
+++ b/scripts/kernel-doc
@@ -1995,6 +1995,7 @@ sub process_file($) {
     my $identifier;
     my $func;
     my $descr;
+    my $in_purpose = 0;
     my $initial_section_counter = $section_counter;
 
     if (defined($ENV{'SRCTREE'})) {
@@ -2044,6 +2045,7 @@ sub process_file($) {
                     $descr =~ s/\s*$//;
                     $descr =~ s/\s+/ /;
                     $declaration_purpose = xml_escape($descr);
+                    $in_purpose = 1;
                 } else {
                     $declaration_purpose = "";
                 }
@@ -2090,6 +2092,7 @@ sub process_file($) {
                 }
 
                 $in_doc_sect = 1;
+                $in_purpose = 0;
                 $contents = $newcontents;
                 if ($contents ne "") {
                     while ((substr($contents, 0, 1) eq " ") ||
@@ -2119,11 +2122,19 @@ sub process_file($) {
             } elsif (/$doc_content/) {
                 # miguel-style comment kludge, look for blank lines after
                 # @parameter line to signify start of description
-                if ($1 eq "" &&
-                        ($section =~ m/^@/ || $section eq $section_context)) {
-                    dump_section($file, $section, xml_escape($contents));
-                    $section = $section_default;
-                    $contents = "";
+                if ($1 eq "") {
+                    if ($section =~ m/^@/ || $section eq $section_context) {
+                        dump_section($file, $section, xml_escape($contents));
+                        $section = $section_default;
+                        $contents = "";
+                    } else {
+                        $contents .= "\n";
+                    }
+                    $in_purpose = 0;
+                } elsif ($in_purpose == 1) {
+                    # Continued declaration purpose
+                    chomp($declaration_purpose);
+                    $declaration_purpose .= " " . xml_escape($1);
                 } else {
                     $contents .= $1 . "\n";
                 }