sys_mmapper: Lazily allocate shared memory descriptors

rpcs3/Emu/Cell/lv2/sys_mmapper.cpp

@@ -36,12 +36,8 @@ lv2_memory::lv2_memory(u32 size, u32 align, u64 flags, u64 key, bool pshared, lv
 	, key(key)
 	, pshared(pshared)
 	, ct(ct)
-	, shm(std::make_shared<utils::shm>(size, 1 /* shareable flag */))
+	, shm(null_ptr)
 {
-#ifndef _WIN32
-	// Optimization that's useless on Windows :puke:
-	utils::memory_lock(shm->map_self(), size);
-#endif
 }
 
 lv2_memory::lv2_memory(utils::serial& ar)
@@ -51,23 +47,17 @@ lv2_memory::lv2_memory(utils::serial& ar)
 	, key(ar)
 	, pshared(ar)
 	, ct(lv2_memory_container::search(ar.pop<u32>()))
-	, shm([&](u32 addr)
+	, shm([&](u32 addr) -> shared_ptr<std::shared_ptr<utils::shm>>
 	{
 		if (addr)
 		{
-			return ensure(vm::get(vm::any, addr)->peek(addr).second);
+			return make_single_value(ensure(vm::get(vm::any, addr)->peek(addr).second));
 		}
 
-		const auto _shm = std::make_shared<utils::shm>(size, 1);
+		return null_ptr;
-		ar(std::span(_shm->map_self(), size));
-		return _shm;
 	}(ar.pop<u32>()))
 	, counter(ar)
 {
-#ifndef _WIN32
-	// Optimization that's useless on Windows :puke:
-	utils::memory_lock(shm->map_self(), size);
-#endif
 }
 
 CellError lv2_memory::on_id_create()
@@ -96,13 +86,7 @@ void lv2_memory::save(utils::serial& ar)
 	USING_SERIALIZATION_VERSION(lv2_memory);
 
 	ar(size, align, flags, key, pshared, ct->id);
-	ar(counter ? vm::get_shm_addr(shm) : 0);
+	ar(counter ? vm::get_shm_addr(*shm.load()) : 0);
-
-	if (!counter)
-	{
-		ar(std::span(shm->map_self(), size));
-	}
-
 	ar(counter);
 }
 
@@ -645,6 +629,18 @@ error_code sys_mmapper_map_shared_memory(ppu_thread& ppu, u32 addr, u32 mem_id,
 			return CELL_EALIGN;
 		}
 
+		while (!mem.shm)
+		{
+			// Insert atomically the memory handle (laziliy allocated)
+			auto shm = make_single_value(std::make_shared<utils::shm>(mem.size, 1 /* shareable flag */));
+			stx::shared_ptr<std::shared_ptr<utils::shm>> null;
+
+			if (mem.shm.compare_exchange(null, std::move(shm)))
+			{
+				break;
+			}
+		}
+
 		mem.counter++;
 		return {};
 	});
@@ -659,7 +655,9 @@ error_code sys_mmapper_map_shared_memory(ppu_thread& ppu, u32 addr, u32 mem_id,
 		return mem.ret;
 	}
 
-	if (!area->falloc(addr, mem->size, &mem->shm, mem->align == 0x10000 ? SYS_MEMORY_PAGE_SIZE_64K : SYS_MEMORY_PAGE_SIZE_1M))
+	auto shm_ptr = *mem->shm.load();
+
+	if (!area->falloc(addr, mem->size, &shm_ptr, mem->align == 0x10000 ? SYS_MEMORY_PAGE_SIZE_64K : SYS_MEMORY_PAGE_SIZE_1M))
 	{
 		mem->counter--;
 
@@ -697,6 +695,18 @@ error_code sys_mmapper_search_and_map(ppu_thread& ppu, u32 start_addr, u32 mem_i
 			return CELL_EALIGN;
 		}
 
+		while (!mem.shm)
+		{
+			// Insert atomically the memory handle (laziliy allocated)
+			auto shm = make_single_value(std::make_shared<utils::shm>(mem.size, 1 /* shareable flag */));
+			stx::shared_ptr<std::shared_ptr<utils::shm>> null;
+
+			if (mem.shm.compare_exchange(null, std::move(shm)))
+			{
+				break;
+			}
+		}
+
 		mem.counter++;
 		return {};
 	});
@@ -711,7 +721,9 @@ error_code sys_mmapper_search_and_map(ppu_thread& ppu, u32 start_addr, u32 mem_i
 		return mem.ret;
 	}
 
-	const u32 addr = area->alloc(mem->size, &mem->shm, mem->align, mem->align == 0x10000 ? SYS_MEMORY_PAGE_SIZE_64K : SYS_MEMORY_PAGE_SIZE_1M);
+	auto shm_ptr = *mem->shm.load();
+
+	const u32 addr = area->alloc(mem->size, &shm_ptr, mem->align, mem->align == 0x10000 ? SYS_MEMORY_PAGE_SIZE_64K : SYS_MEMORY_PAGE_SIZE_1M);
 
 	if (!addr)
 	{
@@ -755,7 +767,7 @@ error_code sys_mmapper_unmap_shared_memory(ppu_thread& ppu, u32 addr, vm::ptr<u3
 
 	const auto mem = idm::select<lv2_obj, lv2_memory>([&](u32 id, lv2_memory& mem) -> u32
 	{
-		if (mem.shm.get() == shm.second.get())
+		if (mem.shm.load()->get() == shm.second.get())
 		{
 			return id;
 		}

rpcs3/Emu/Cell/lv2/sys_mmapper.h

@@ -5,6 +5,8 @@
 #include "Emu/Memory/vm_ptr.h"
 #include "Emu/Cell/ErrorCodes.h"
 
+#include "util/shared_ptr.hpp"
+
 #include <vector>
 
 struct lv2_memory_container;
@@ -24,7 +26,7 @@ struct lv2_memory : lv2_obj
 	const u64 key; // IPC key
 	const bool pshared; // Process shared flag
 	lv2_memory_container* const ct; // Associated memory container
-	const std::shared_ptr<utils::shm> shm;
+	atomic_ptr<std::shared_ptr<utils::shm>> shm;
 
 	atomic_t<u32> counter{0};