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

1 files changed, 7 insertions, 2 deletions

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;
 }