kernel-doc: improve "no structured comments found" error

When using '!Ffile function' in a docbook template, and the function no
longer exists, you get a "no structured comments found" error from the
kernel-doc processing script.  It's useful to know which functions it was
looking for, so print them out in this case.  Also do the same for '!Pfile
doc-section'

The same error also happens when using '!Efile' when some exported
functions aren't documented (in the same file.) There's a very large
number of such functions though, so don't print the message in this case
-- right now it would give ~850 messages.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Cc: Rob Landley <rob@landley.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/scripts/kernel-doc b/scripts/kernel-doc
index 4305b2f..dbd3e1e 100755
--- a/scripts/kernel-doc
+++ b/scripts/kernel-doc
@@ -257,6 +257,7 @@
 		'July', 'August', 'September', 'October',
 		'November', 'December')[(localtime)[4]] .
   " " . ((localtime)[5]+1900);
+my $show_not_found = 0;
 
 # Essentially these are globals.
 # They probably want to be tidied up, made more localised or something.
@@ -369,6 +370,8 @@
 	usage();
     } elsif ($cmd eq '-no-doc-sections') {
 	    $no_doc_sections = 1;
+    } elsif ($cmd eq '-show-not-found') {
+	$show_not_found = 1;
     }
 }
 
@@ -2536,6 +2539,9 @@
     }
     if ($initial_section_counter == $section_counter) {
 	print STDERR "Warning(${file}): no structured comments found\n";
+	if (($function_only == 1) && ($show_not_found == 1)) {
+	    print STDERR "    Was looking for '$_'.\n" for keys %function_table;
+	}
 	if ($output_mode eq "xml") {
 	    # The template wants at least one RefEntry here; make one.
 	    print "<refentry>\n";