depmod: cache dependency_symbol list in struct mod

The overall goal is to coalesce the accesses to a file that is the
backend of a module. This commit addresses the calls to
kmod_module_get_get_dependency_symbols(). Calling it earlier, while we
are iterating the modules allows us to free the struct kmod of each
module much sooner. We are still not freeing it since there are other
places that must be refactored first.

There's a performance penalty of ~2.5% from previous commit.

1 files changed, 15 insertions, 11 deletions

diff --git a/tools/depmod.c b/tools/depmod.c
index 5423bad..0664725 100644
--- a/tools/depmod.c
+++ b/tools/depmod.c
@@ -997,6 +997,7 @@ struct mod {
 	const char *relpath; /* path relative to '$ROOT/lib/modules/$VER/' */
 	char *uncrelpath; /* same as relpath but ending in .ko */
 	struct kmod_list *info_list;
+	struct kmod_list *dep_sym_list;
 	struct array deps; /* struct symbol */
 	size_t baselen; /* points to start of basename/filename */
 	size_t modnamelen;
@@ -1030,6 +1031,7 @@ static void mod_free(struct mod *mod)
 	array_free_array(&mod->deps);
 	kmod_module_unref(mod->kmod);
 	kmod_module_info_free_list(mod->info_list);
+	kmod_module_dependency_symbols_free_list(mod->dep_sym_list);
 	free(mod->uncrelpath);
 	free(mod);
 }
@@ -1543,7 +1545,7 @@ static struct symbol *depmod_symbol_find(const struct depmod *depmod,
 	return hash_find(depmod->symbols, name);
 }
 
-static int depmod_load_symbols_and_info(struct depmod *depmod)
+static int depmod_load_modules(struct depmod *depmod)
 {
 	struct mod **itr, **itr_end;
 
@@ -1572,6 +1574,8 @@ static int depmod_load_symbols_and_info(struct depmod *depmod)
 
 load_info:
 		kmod_module_get_info(mod->kmod, &mod->info_list);
+		kmod_module_get_dependency_symbols(mod->kmod,
+						   &mod->dep_sym_list);
 	}
 
 	DBG("loaded symbols (%zd modules, %zd symbols)\n",
@@ -1583,16 +1587,10 @@ load_info:
 static int depmod_load_module_dependencies(struct depmod *depmod, struct mod *mod)
 {
 	const struct cfg *cfg = depmod->cfg;
-	struct kmod_list *l, *list = NULL;
-	int err = kmod_module_get_dependency_symbols(mod->kmod, &list);
-	if (err < 0) {
-		DBG("ignoring %s: no dependency symbols: %s\n",
-		    mod->path, strerror(-err));
-		return 0;
-	}
+	struct kmod_list *l;
 
 	DBG("do dependencies of %s\n", mod->path);
-	kmod_list_foreach(l, list) {
+	kmod_list_foreach(l, mod->dep_sym_list) {
 		const char *name = kmod_module_dependency_symbol_get_symbol(l);
 		uint64_t crc = kmod_module_dependency_symbol_get_crc(l);
 		int bindtype = kmod_module_dependency_symbol_get_bind(l);
@@ -1618,7 +1616,7 @@ static int depmod_load_module_dependencies(struct depmod *depmod, struct mod *mo
 
 		mod_add_dependency(mod, sym);
 	}
-	kmod_module_dependency_symbols_free_list(list);
+
 	return 0;
 }
 
@@ -1633,6 +1631,12 @@ static int depmod_load_dependencies(struct depmod *depmod)
 	itr_end = itr + depmod->modules.count;
 	for (; itr < itr_end; itr++) {
 		struct mod *mod = *itr;
+
+		if (mod->dep_sym_list == NULL) {
+			DBG("ignoring %s: no dependency symbols\n", mod->path);
+			continue;
+		}
+
 		depmod_load_module_dependencies(depmod, mod);
 	}
 
@@ -1747,7 +1751,7 @@ static int depmod_load(struct depmod *depmod)
 {
 	int err;
 
-	err = depmod_load_symbols_and_info(depmod);
+	err = depmod_load_modules(depmod);
 	if (err < 0)
 		return err;