1.1 --- a/src/share/vm/runtime/os.cpp Thu Jan 31 14:56:50 2008 -0500
1.2 +++ b/src/share/vm/runtime/os.cpp Tue Feb 05 23:21:57 2008 -0800
1.3 @@ -956,7 +956,6 @@
1.4 return true;
1.5 }
1.6
1.7 -
1.8 void os::set_memory_serialize_page(address page) {
1.9 int count = log2_intptr(sizeof(class JavaThread)) - log2_intptr(64);
1.10 _mem_serialize_page = (volatile int32_t *)page;
1.11 @@ -967,6 +966,8 @@
1.12 set_serialize_page_mask((uintptr_t)(vm_page_size() - sizeof(int32_t)));
1.13 }
1.14
1.15 +static volatile intptr_t SerializePageLock = 0;
1.16 +
1.17 // This method is called from signal handler when SIGSEGV occurs while the current
1.18 // thread tries to store to the "read-only" memory serialize page during state
1.19 // transition.
1.20 @@ -974,15 +975,14 @@
1.21 if (TraceSafepoint) {
1.22 tty->print_cr("Block until the serialize page permission restored");
1.23 }
1.24 - // When VMThread is holding the SerializePage_lock during modifying the
1.25 + // When VMThread is holding the SerializePageLock during modifying the
1.26 // access permission of the memory serialize page, the following call
1.27 // will block until the permission of that page is restored to rw.
1.28 // Generally, it is unsafe to manipulate locks in signal handlers, but in
1.29 // this case, it's OK as the signal is synchronous and we know precisely when
1.30 - // it can occur. SerializePage_lock is a transiently-held leaf lock, so
1.31 - // lock_without_safepoint_check should be safe.
1.32 - SerializePage_lock->lock_without_safepoint_check();
1.33 - SerializePage_lock->unlock();
1.34 + // it can occur.
1.35 + Thread::muxAcquire(&SerializePageLock, "set_memory_serialize_page");
1.36 + Thread::muxRelease(&SerializePageLock);
1.37 }
1.38
1.39 // Serialize all thread state variables
1.40 @@ -990,14 +990,12 @@
1.41 // On some platforms such as Solaris & Linux, the time duration of the page
1.42 // permission restoration is observed to be much longer than expected due to
1.43 // scheduler starvation problem etc. To avoid the long synchronization
1.44 - // time and expensive page trap spinning, 'SerializePage_lock' is used to block
1.45 - // the mutator thread if such case is encountered. Since this method is always
1.46 - // called by VMThread during safepoint, lock_without_safepoint_check is used
1.47 - // instead. See bug 6546278.
1.48 - SerializePage_lock->lock_without_safepoint_check();
1.49 + // time and expensive page trap spinning, 'SerializePageLock' is used to block
1.50 + // the mutator thread if such case is encountered. See bug 6546278 for details.
1.51 + Thread::muxAcquire(&SerializePageLock, "serialize_thread_states");
1.52 os::protect_memory( (char *)os::get_memory_serialize_page(), os::vm_page_size() );
1.53 os::unguard_memory( (char *)os::get_memory_serialize_page(), os::vm_page_size() );
1.54 - SerializePage_lock->unlock();
1.55 + Thread::muxRelease(&SerializePageLock);
1.56 }
1.57
1.58 // Returns true if the current stack pointer is above the stack shadow
