modpost: dump missing namespaces into a single modules.nsdeps file

The modpost, with the -d option given, generates per-module .ns_deps
files.

Kbuild generates per-module .mod files to carry module information.
This is convenient because Make handles multiple jobs in parallel
when the -j option is given.

On the other hand, the modpost always runs as a single thread.
I do not see a strong reason to produce separate .ns_deps files.

This commit changes the modpost to generate just one file,
modules.nsdeps, each line of which has the following format:

<module_name>: <list of missing namespaces>

Please note it contains *missing* namespaces instead of required ones.
So, modules.nsdeps is empty if the namespace dependency is all good.

This will work more efficiently because spatch will no longer process
already imported namespaces. I removed the '(if needed)' from the
nsdeps log since spatch is invoked only when needed.

This also solves the stale .ns_deps problem reported by Jessica Yu:

https://lkml.org/lkml/2019/10/28/467

Signed-off-by: Masahiro Yamada <[e-mail]>
Tested-by: Jessica Yu <[e-mail]>
Acked-by: Jessica Yu <[e-mail]>
Reviewed-by: Matthias Maennich <[e-mail]>
Tested-by: Matthias Maennich <[e-mail]>

.gitignore

···
 *.lzo
 *.mod
 *.mod.c
-*.ns_deps
 *.o
 *.o.*
 *.patch
···
 /System.map
 /Module.markers
 /modules.builtin.modinfo
+/modules.nsdeps
 
 #
 # RPM spec file (make rpm-pkg)

Documentation/dontdiff

···
 modpost
 modules.builtin
 modules.builtin.modinfo
+modules.nsdeps
 modules.order
 modversions.h*
 nconf

Makefile

···
 
 # Directories & files removed with 'make clean'
 CLEAN_DIRS  += include/ksym
-CLEAN_FILES += modules.builtin.modinfo
+CLEAN_FILES += modules.builtin.modinfo modules.nsdeps
 
 # Directories & files removed with 'make mrproper'
 MRPROPER_DIRS  += include/config include/generated          \
···
 		-o -name '*.ko.*' \
 		-o -name '*.dtb' -o -name '*.dtb.S' -o -name '*.dt.yaml' \
 		-o -name '*.dwo' -o -name '*.lst' \
-		-o -name '*.su' -o -name '*.mod' -o -name '*.ns_deps' \
+		-o -name '*.su' -o -name '*.mod' \
 		-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
 		-o -name '*.lex.c' -o -name '*.tab.[ch]' \
 		-o -name '*.asn1.[ch]' \

scripts/Makefile.modpost

···
 else
 
 MODPOST += $(subst -i,-n,$(filter -i,$(MAKEFLAGS))) -s -T - \
-	$(if $(KBUILD_NSDEPS),-d)
+	$(if $(KBUILD_NSDEPS),-d modules.nsdeps)
 
 ifeq ($(KBUILD_EXTMOD),)
 MODPOST += $(wildcard vmlinux)

scripts/mod/modpost.c

···
 static int sec_mismatch_fatal = 0;
 /* ignore missing files */
 static int ignore_missing_files;
-/* write namespace dependencies */
-static int write_namespace_deps;
 
 enum export {
 	export_plain,      export_unused,     export_gpl,
···
 		else
 			basename = mod->name;
 
-		if (exp->namespace) {
-			add_namespace(&mod->required_namespaces,
-				      exp->namespace);
-
-			if (!module_imports_namespace(mod, exp->namespace)) {
-				warn("module %s uses symbol %s from namespace %s, but does not import it.\n",
-				     basename, exp->name, exp->namespace);
-			}
+		if (exp->namespace &&
+		    !module_imports_namespace(mod, exp->namespace)) {
+			warn("module %s uses symbol %s from namespace %s, but does not import it.\n",
+			     basename, exp->name, exp->namespace);
+			add_namespace(&mod->missing_namespaces, exp->namespace);
 		}
 
 		if (!mod->gpl_compatible)
···
 	free(buf.p);
 }
 
-static void write_namespace_deps_files(void)
+static void write_namespace_deps_files(const char *fname)
 {
 	struct module *mod;
 	struct namespace_list *ns;
 	struct buffer ns_deps_buf = {};
 
 	for (mod = modules; mod; mod = mod->next) {
-		char fname[PATH_MAX];
 
-		if (mod->skip)
+		if (mod->skip || !mod->missing_namespaces)
 			continue;
 
-		ns_deps_buf.pos = 0;
+		buf_printf(&ns_deps_buf, "%s.ko:", mod->name);
 
-		for (ns = mod->required_namespaces; ns; ns = ns->next)
-			buf_printf(&ns_deps_buf, "%s\n", ns->namespace);
+		for (ns = mod->missing_namespaces; ns; ns = ns->next)
+			buf_printf(&ns_deps_buf, " %s", ns->namespace);
 
-		if (ns_deps_buf.pos == 0)
-			continue;
-
-		sprintf(fname, "%s.ns_deps", mod->name);
-		write_if_changed(&ns_deps_buf, fname);
+		buf_printf(&ns_deps_buf, "\n");
 	}
 
+	write_if_changed(&ns_deps_buf, fname);
 	free(ns_deps_buf.p);
 }
 
···
 	struct module *mod;
 	struct buffer buf = { };
 	char *kernel_read = NULL;
+	char *missing_namespace_deps = NULL;
 	char *dump_write = NULL, *files_source = NULL;
 	int opt;
 	int err;
···
 	struct ext_sym_list *extsym_iter;
 	struct ext_sym_list *extsym_start = NULL;
 
-	while ((opt = getopt(argc, argv, "i:e:mnsT:o:awEd")) != -1) {
+	while ((opt = getopt(argc, argv, "i:e:mnsT:o:awEd:")) != -1) {
 		switch (opt) {
 		case 'i':
 			kernel_read = optarg;
···
 			sec_mismatch_fatal = 1;
 			break;
 		case 'd':
-			write_namespace_deps = 1;
+			missing_namespace_deps = optarg;
 			break;
 		default:
 			exit(1);
···
 		write_if_changed(&buf, fname);
 	}
 
-	if (write_namespace_deps)
-		write_namespace_deps_files();
+	if (missing_namespace_deps)
+		write_namespace_deps_files(missing_namespace_deps);
 
 	if (dump_write)
 		write_dump(dump_write);

scripts/mod/modpost.h

···
 	struct buffer dev_table_buf;
 	char	     srcversion[25];
 	int is_dot_o;
-	// Required namespace dependencies
-	struct namespace_list *required_namespaces;
+	// Missing namespace dependencies
+	struct namespace_list *missing_namespaces;
 	// Actual imported namespaces
 	struct namespace_list *imported_namespaces;
 };

scripts/nsdeps

···
 }
 
 generate_deps() {
-	local mod_name=`basename $@ .ko`
-	local mod_file=`echo $@ | sed -e 's/\.ko/\.mod/'`
-	local ns_deps_file=`echo $@ | sed -e 's/\.ko/\.ns_deps/'`
-	if [ ! -f "$ns_deps_file" ]; then return; fi
-	local mod_source_files="`cat $mod_file | sed -n 1p                      \
+	local mod=${1%.ko:}
+	shift
+	local namespaces="$*"
+	local mod_source_files="`cat $mod.mod | sed -n 1p                      \
 					      | sed -e 's/\.o/\.c/g'           \
 					      | sed "s|[^ ]* *|${srctree}/&|g"`"
-	for ns in `cat $ns_deps_file`; do
-		echo "Adding namespace $ns to module $mod_name (if needed)."
+	for ns in $namespaces; do
+		echo "Adding namespace $ns to module $mod.ko."
 		generate_deps_for_ns $ns "$mod_source_files"
 		# sort the imports
 		for source_file in $mod_source_files; do
···
 	done
 }
 
-for f in `cat $objtree/modules.order`; do
-	generate_deps $f
-done
-
+while read line
+do
+	generate_deps $line
+done < modules.nsdeps