From 8c1051918e1aaf7610ddb0e6ef5cb6d97abe3d82 Mon Sep 17 00:00:00 2001
From: Mark Salyzyn <salyzyn@google.com>
Date: Tue, 29 Oct 2019 08:38:55 -0700
Subject: [PATCH] libmodprobe: Do not reload modules previously instantiated

For modprobe operation.

For an interlocking driver set of about 50 modules, the impact of
their dependencies resulted in a 30 second impact in boot time
trying to load previously loaded modules. This impact is handily
eliminated by keeping a list of modules paths that have been loaded
and skipping them proactively.

Test: Confirmed device boot and 50 module set of drivers functions.
Test: libmodprobe_tests
Bug: 142938937
Bug: 140827934
Change-Id: Iccd11399d6043b38cbd5f93578ee202022e7770c
---
 libmodprobe/include/modprobe/modprobe.h | 2 ++
 libmodprobe/libmodprobe.cpp             | 8 +++++++-
 libmodprobe/libmodprobe_ext.cpp         | 9 +++++++--
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/libmodprobe/include/modprobe/modprobe.h b/libmodprobe/include/modprobe/modprobe.h
index dcb4ffbef..421d82644 100644
--- a/libmodprobe/include/modprobe/modprobe.h
+++ b/libmodprobe/include/modprobe/modprobe.h
@@ -19,6 +19,7 @@
 #include <set>
 #include <string>
 #include <unordered_map>
+#include <unordered_set>
 #include <vector>
 
 class Modprobe {
@@ -59,5 +60,6 @@ class Modprobe {
     std::vector<std::string> module_load_;
     std::unordered_map<std::string, std::string> module_options_;
     std::set<std::string> module_blacklist_;
+    std::unordered_set<std::string> module_loaded_;
     bool blacklist_enabled = false;
 };
diff --git a/libmodprobe/libmodprobe.cpp b/libmodprobe/libmodprobe.cpp
index 73ae15b07..3c78ec999 100644
--- a/libmodprobe/libmodprobe.cpp
+++ b/libmodprobe/libmodprobe.cpp
@@ -330,7 +330,12 @@ bool Modprobe::InsmodWithDeps(const std::string& module_name, const std::string&
 
 bool Modprobe::LoadWithAliases(const std::string& module_name, bool strict,
                                const std::string& parameters) {
-    std::set<std::string> modules_to_load = {MakeCanonical(module_name)};
+    auto canonical_name = MakeCanonical(module_name);
+    if (module_loaded_.count(canonical_name)) {
+        return true;
+    }
+
+    std::set<std::string> modules_to_load = {canonical_name};
     bool module_loaded = false;
 
     // use aliases to expand list of modules to load (multiple modules
@@ -338,6 +343,7 @@ bool Modprobe::LoadWithAliases(const std::string& module_name, bool strict,
     for (const auto& [alias, aliased_module] : module_aliases_) {
         if (fnmatch(alias.c_str(), module_name.c_str(), 0) != 0) continue;
         LOG(VERBOSE) << "Found alias for '" << module_name << "': '" << aliased_module;
+        if (module_loaded_.count(MakeCanonical(aliased_module))) continue;
         modules_to_load.emplace(aliased_module);
     }
 
diff --git a/libmodprobe/libmodprobe_ext.cpp b/libmodprobe/libmodprobe_ext.cpp
index 2efcac290..8bebe4c9f 100644
--- a/libmodprobe/libmodprobe_ext.cpp
+++ b/libmodprobe/libmodprobe_ext.cpp
@@ -30,8 +30,9 @@ bool Modprobe::Insmod(const std::string& path_name, const std::string& parameter
         return false;
     }
 
+    auto canonical_name = MakeCanonical(path_name);
     std::string options = "";
-    auto options_iter = module_options_.find(MakeCanonical(path_name));
+    auto options_iter = module_options_.find(canonical_name);
     if (options_iter != module_options_.end()) {
         options = options_iter->second;
     }
@@ -44,6 +45,7 @@ bool Modprobe::Insmod(const std::string& path_name, const std::string& parameter
     if (ret != 0) {
         if (errno == EEXIST) {
             // Module already loaded
+            module_loaded_.emplace(canonical_name);
             return true;
         }
         LOG(ERROR) << "Failed to insmod '" << path_name << "' with args '" << options << "'";
@@ -51,15 +53,18 @@ bool Modprobe::Insmod(const std::string& path_name, const std::string& parameter
     }
 
     LOG(INFO) << "Loaded kernel module " << path_name;
+    module_loaded_.emplace(canonical_name);
     return true;
 }
 
 bool Modprobe::Rmmod(const std::string& module_name) {
-    int ret = syscall(__NR_delete_module, MakeCanonical(module_name).c_str(), O_NONBLOCK);
+    auto canonical_name = MakeCanonical(module_name);
+    int ret = syscall(__NR_delete_module, canonical_name.c_str(), O_NONBLOCK);
     if (ret != 0) {
         PLOG(ERROR) << "Failed to remove module '" << module_name << "'";
         return false;
     }
+    module_loaded_.erase(canonical_name);
     return true;
 }