MDEV-21534 fixup: Remove HAVE_IB_LINUX_FUTEX

Since commit 30ea63b7
we actually depend on futex on Linux. Also, we depend on
std::atomic for even longer.

storage/innobase/include/ib0mutex.h

@@ -145,7 +145,7 @@ struct OSTrackMutex {
 };
 
 
-#ifdef HAVE_IB_LINUX_FUTEX
+#ifdef __linux__
 
 #include <linux/futex.h>
 #include <sys/syscall.h>
@@ -261,7 +261,7 @@ struct TTASFutexMutex {
 	std::atomic<int32>	m_lock_word;
 };
 
-#endif /* HAVE_IB_LINUX_FUTEX */
+#endif /* __linux__ */
 
 template <template <typename> class Policy>
 struct TTASMutex {

storage/innobase/include/ut0mutex.h

@@ -24,11 +24,8 @@ Policy based mutexes.
 Created 2012-03-24 Sunny Bains.
 ***********************************************************************/
 
+#pragma once
 #ifndef UNIV_INNOCHECKSUM
-
-#ifndef ut0mutex_h
-#define ut0mutex_h
-
 #include "sync0policy.h"
 #include "ib0mutex.h"
 
@@ -38,9 +35,9 @@ Created 2012-03-24 Sunny Bains.
 @param[in]	T		The resulting typedef alias */
 #define UT_MUTEX_TYPE(M, P, T) typedef PolicyMutex<M<P> > T;
 
-# ifdef HAVE_IB_LINUX_FUTEX
+# ifdef __linux__
 UT_MUTEX_TYPE(TTASFutexMutex, GenericPolicy, FutexMutex);
-# endif /* HAVE_IB_LINUX_FUTEX */
+# endif /* __linux__ */
 
 UT_MUTEX_TYPE(TTASMutex, GenericPolicy, SpinMutex);
 UT_MUTEX_TYPE(OSTrackMutex, GenericPolicy, SysMutex);
@@ -178,6 +175,4 @@ void mutex_destroy(
 	mutex->destroy();
 }
 
-#endif /* ut0mutex_h */
-
 #endif /* UNIV_INNOCHECKSUM */

storage/innobase/innodb.cmake

@@ -82,8 +82,6 @@ IF(INNODB_COMPILER_HINTS)
    ADD_DEFINITIONS("-DCOMPILER_HINTS")
 ENDIF()
 
-SET(MUTEXTYPE "event" CACHE STRING "Mutex type: event, sys or futex")
-
 # Enable InnoDB's UNIV_DEBUG in debug builds
 SET(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -DUNIV_DEBUG")
 
@@ -130,48 +128,8 @@ IF(NOT MSVC)
      CMAKE_C_COMPILER_VERSION VERSION_LESS "6.0.0")
     SET_SOURCE_FILES_PROPERTIES(trx/trx0rec.cc PROPERTIES COMPILE_FLAGS -O1)
   ENDIF()
-
-# Only use futexes on Linux if GCC atomics are available
-IF(NOT MSVC AND NOT CMAKE_CROSSCOMPILING)
-  CHECK_C_SOURCE_RUNS(
-  "
-  #include <stdio.h>
-  #include <unistd.h>
-  #include <errno.h>
-  #include <assert.h>
-  #include <linux/futex.h>
-  #include <unistd.h>
-  #include <sys/syscall.h>
-
-   int futex_wait(int* futex, int v) {
-	return(syscall(SYS_futex, futex, FUTEX_WAIT_PRIVATE, v, NULL, NULL, 0));
-   }
-
-   int futex_signal(int* futex) {
-	return(syscall(SYS_futex, futex, FUTEX_WAKE, 1, NULL, NULL, 0));
-   }
-
-  int main() {
-	int	ret;
-	int	m = 1;
-
-	/* It is setup to fail and return EWOULDBLOCK. */
-	ret = futex_wait(&m, 0);
-	assert(ret == -1 && errno == EWOULDBLOCK);
-	/* Shouldn't wake up any threads. */
-	assert(futex_signal(&m) == 0);
-
-	return(0);
-  }"
-  HAVE_IB_LINUX_FUTEX)
 ENDIF()
 
-IF(HAVE_IB_LINUX_FUTEX)
-  ADD_DEFINITIONS(-DHAVE_IB_LINUX_FUTEX=1)
-ENDIF()
-
-ENDIF(NOT MSVC)
-
 CHECK_FUNCTION_EXISTS(vasprintf  HAVE_VASPRINTF)
 
 CHECK_CXX_SOURCE_COMPILES("struct t1{ int a; char *b; }; struct t1 c= { .a=1, .b=0 }; main() { }" HAVE_C99_INITIALIZERS)
@@ -183,7 +141,7 @@ SET(MUTEXTYPE "event" CACHE STRING "Mutex type: event, sys or futex")
 
 IF(MUTEXTYPE MATCHES "event")
   ADD_DEFINITIONS(-DMUTEX_EVENT)
-ELSEIF(MUTEXTYPE MATCHES "futex" AND DEFINED HAVE_IB_LINUX_FUTEX)
+ELSEIF(MUTEXTYPE MATCHES "futex" AND CMAKE_SYSTEM_NAME STREQUAL "Linux")
   ADD_DEFINITIONS(-DMUTEX_FUTEX)
 ELSE()
    ADD_DEFINITIONS(-DMUTEX_SYS)