--- a/hotspot/src/share/vm/runtime/os.cpp Thu Jan 31 14:56:50 2008 -0500
+++ b/hotspot/src/share/vm/runtime/os.cpp Tue Feb 05 23:21:57 2008 -0800
@@ -956,7 +956,6 @@
return true;
}
-
void os::set_memory_serialize_page(address page) {
int count = log2_intptr(sizeof(class JavaThread)) - log2_intptr(64);
_mem_serialize_page = (volatile int32_t *)page;
@@ -967,6 +966,8 @@
set_serialize_page_mask((uintptr_t)(vm_page_size() - sizeof(int32_t)));
}
+static volatile intptr_t SerializePageLock = 0;
+
// This method is called from signal handler when SIGSEGV occurs while the current
// thread tries to store to the "read-only" memory serialize page during state
// transition.
@@ -974,15 +975,14 @@
if (TraceSafepoint) {
tty->print_cr("Block until the serialize page permission restored");
}
- // When VMThread is holding the SerializePage_lock during modifying the
+ // When VMThread is holding the SerializePageLock during modifying the
// access permission of the memory serialize page, the following call
// will block until the permission of that page is restored to rw.
// Generally, it is unsafe to manipulate locks in signal handlers, but in
// this case, it's OK as the signal is synchronous and we know precisely when
- // it can occur. SerializePage_lock is a transiently-held leaf lock, so
- // lock_without_safepoint_check should be safe.
- SerializePage_lock->lock_without_safepoint_check();
- SerializePage_lock->unlock();
+ // it can occur.
+ Thread::muxAcquire(&SerializePageLock, "set_memory_serialize_page");
+ Thread::muxRelease(&SerializePageLock);
}
// Serialize all thread state variables
@@ -990,14 +990,12 @@
// On some platforms such as Solaris & Linux, the time duration of the page
// permission restoration is observed to be much longer than expected due to
// scheduler starvation problem etc. To avoid the long synchronization
- // time and expensive page trap spinning, 'SerializePage_lock' is used to block
- // the mutator thread if such case is encountered. Since this method is always
- // called by VMThread during safepoint, lock_without_safepoint_check is used
- // instead. See bug 6546278.
- SerializePage_lock->lock_without_safepoint_check();
+ // time and expensive page trap spinning, 'SerializePageLock' is used to block
+ // the mutator thread if such case is encountered. See bug 6546278 for details.
+ Thread::muxAcquire(&SerializePageLock, "serialize_thread_states");
os::protect_memory( (char *)os::get_memory_serialize_page(), os::vm_page_size() );
os::unguard_memory( (char *)os::get_memory_serialize_page(), os::vm_page_size() );
- SerializePage_lock->unlock();
+ Thread::muxRelease(&SerializePageLock);
}
// Returns true if the current stack pointer is above the stack shadow