From: Jonathan Wakely <jwakely@redhat.com>
Date: Thu, 9 Jan 2025 23:03:50 +0000 (+0000)
Subject: libstdc++: Simplify futex wrapper functions for atomic wait/notify
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f52948bf8e5f3b0a72a903b3b26e5d54d2929723;p=thirdparty%2Fgcc.git

libstdc++: Simplify futex wrapper functions for atomic wait/notify

libstdc++-v3/ChangeLog:

	* include/bits/atomic_wait.h (__platform_wait): Change function
	template to a normal function. The parameter is always
	__platform_wait_t* which is just int* for this implementation of
	the function.
	(__platform_notify): Likewise.
---

diff --git a/libstdc++-v3/include/bits/atomic_wait.h b/libstdc++-v3/include/bits/atomic_wait.h
index 725ea030245..5fd00c22565 100644
--- a/libstdc++-v3/include/bits/atomic_wait.h
+++ b/libstdc++-v3/include/bits/atomic_wait.h
@@ -108,27 +108,27 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       __bitset_match_any = -1
     };
 
-    template<typename _Tp>
-      void
-      __platform_wait(const _Tp* __addr, __platform_wait_t __val) noexcept
-      {
-	auto __e = syscall (SYS_futex, static_cast<const void*>(__addr),
-			    static_cast<int>(__futex_wait_flags::__wait_private),
-			    __val, nullptr);
-	if (!__e || errno == EAGAIN)
-	  return;
-	if (errno != EINTR)
-	  __throw_system_error(errno);
-      }
+    // If the futex *__addr is equal to __val, wait on the futex until woken.
+    inline void
+    __platform_wait(const int* __addr, int __val) noexcept
+    {
+      auto __e = syscall (SYS_futex, __addr,
+			  static_cast<int>(__futex_wait_flags::__wait_private),
+			  __val, nullptr);
+      if (!__e || errno == EAGAIN)
+	return;
+      if (errno != EINTR)
+	__throw_system_error(errno);
+    }
 
-    template<typename _Tp>
-      void
-      __platform_notify(const _Tp* __addr, bool __all) noexcept
-      {
-	syscall (SYS_futex, static_cast<const void*>(__addr),
-		 static_cast<int>(__futex_wait_flags::__wake_private),
-		 __all ? INT_MAX : 1);
-      }
+    // Wake threads waiting on the futex *__addr.
+    inline void
+    __platform_notify(const int* __addr, bool __all) noexcept
+    {
+      syscall (SYS_futex, __addr,
+	       static_cast<int>(__futex_wait_flags::__wake_private),
+	       __all ? INT_MAX : 1);
+    }
 #endif
 
     inline void