/* $Id: semxroads-generic.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */ /** @file * IPRT Testcase - RTSemXRoads, generic implementation. */ /* * Copyright (C) 2009-2023 Oracle and/or its affiliates. * * This file is part of VirtualBox base platform packages, as * available from https://www.virtualbox.org. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation, in version 3 of the * License. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see . * * The contents of this file may alternatively be used under the terms * of the Common Development and Distribution License Version 1.0 * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included * in the VirtualBox distribution, in which case the provisions of the * CDDL are applicable instead of those of the GPL. * * You may elect to license modified versions of this file under the * terms and conditions of either the GPL or the CDDL or both. * * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0 */ /********************************************************************************************************************************* * Header Files * *********************************************************************************************************************************/ #define RTASSERT_QUIET #include #include "internal/iprt.h" #include #include #include #include #include #include "internal/magics.h" /********************************************************************************************************************************* * Structures and Typedefs * *********************************************************************************************************************************/ typedef struct RTSEMXROADSINTERNAL { /** Magic value (RTSEMXROADS_MAGIC). */ uint32_t volatile u32Magic; uint32_t u32Padding; /**< alignment padding.*/ /* The state variable. * All accesses are atomic and it bits are defined like this: * Bits 0..14 - cNorthSouth. * Bit 15 - Unused. * Bits 16..31 - cEastWest. * Bit 31 - fDirection; 0=NS, 1=EW. * Bits 32..46 - cWaitingNS * Bit 47 - Unused. * Bits 48..62 - cWaitingEW * Bit 63 - Unused. */ uint64_t volatile u64State; /** Per-direction data. */ struct { /** What the north/south bound threads are blocking on when waiting for * east/west traffic to stop. */ RTSEMEVENTMULTI hEvt; /** Indicates whether the semaphore needs resetting. */ bool volatile fNeedReset; } aDirs[2]; } RTSEMXROADSINTERNAL; /********************************************************************************************************************************* * Defined Constants And Macros * *********************************************************************************************************************************/ #define RTSEMXROADS_CNT_BITS 15 #define RTSEMXROADS_CNT_MASK UINT64_C(0x00007fff) #define RTSEMXROADS_CNT_NS_SHIFT 0 #define RTSEMXROADS_CNT_NS_MASK (RTSEMXROADS_CNT_MASK << RTSEMXROADS_CNT_NS_SHIFT) #define RTSEMXROADS_CNT_EW_SHIFT 16 #define RTSEMXROADS_CNT_EW_MASK (RTSEMXROADS_CNT_MASK << RTSEMXROADS_CNT_EW_SHIFT) #define RTSEMXROADS_DIR_SHIFT 31 #define RTSEMXROADS_DIR_MASK RT_BIT_64(RTSEMXROADS_DIR_SHIFT) #define RTSEMXROADS_WAIT_CNT_NS_SHIFT 32 #define RTSEMXROADS_WAIT_CNT_NS_MASK (RTSEMXROADS_CNT_MASK << RTSEMXROADS_WAIT_CNT_NS_SHIFT) #define RTSEMXROADS_WAIT_CNT_EW_SHIFT 48 #define RTSEMXROADS_WAIT_CNT_EW_MASK (RTSEMXROADS_CNT_MASK << RTSEMXROADS_WAIT_CNT_EW_SHIFT) #if 0 /* debugging aid */ static uint32_t volatile g_iHist = 0; static struct { void *tsc; RTTHREAD hThread; uint32_t line; bool fDir; void *u64State; void *u64OldState; bool fNeedResetNS; bool fNeedResetEW; const char *psz; } g_aHist[256]; # define add_hist(ns, os, dir, what) \ do \ { \ uint32_t i = (ASMAtomicIncU32(&g_iHist) - 1) % RT_ELEMENTS(g_aHist);\ g_aHist[i].line = __LINE__; \ g_aHist[i].u64OldState = (void *)(os); \ g_aHist[i].u64State = (void *)(ns); \ g_aHist[i].fDir = (dir); \ g_aHist[i].psz = (what); \ g_aHist[i].fNeedResetNS = pThis->aDirs[0].fNeedReset; \ g_aHist[i].fNeedResetEW = pThis->aDirs[1].fNeedReset; \ g_aHist[i].hThread = RTThreadSelf(); \ g_aHist[i].tsc = (void *)ASMReadTSC(); \ } while (0) # undef DECL_FORCE_INLINE # define DECL_FORCE_INLINE(type) static type #else # define add_hist(ns, os, dir, what) do { } while (0) #endif RTDECL(int) RTSemXRoadsCreate(PRTSEMXROADS phXRoads) { RTSEMXROADSINTERNAL *pThis = (RTSEMXROADSINTERNAL *)RTMemAlloc(sizeof(*pThis)); if (!pThis) return VERR_NO_MEMORY; int rc = RTSemEventMultiCreate(&pThis->aDirs[0].hEvt); if (RT_SUCCESS(rc)) { rc = RTSemEventMultiCreate(&pThis->aDirs[1].hEvt); if (RT_SUCCESS(rc)) { pThis->u32Magic = RTSEMXROADS_MAGIC; pThis->u32Padding = 0; pThis->u64State = 0; pThis->aDirs[0].fNeedReset = false; pThis->aDirs[1].fNeedReset = false; *phXRoads = pThis; return VINF_SUCCESS; } RTSemEventMultiDestroy(pThis->aDirs[0].hEvt); } return rc; } RTDECL(int) RTSemXRoadsDestroy(RTSEMXROADS hXRoads) { /* * Validate input. */ RTSEMXROADSINTERNAL *pThis = hXRoads; if (pThis == NIL_RTSEMXROADS) return VINF_SUCCESS; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertReturn(pThis->u32Magic == RTSEMXROADS_MAGIC, VERR_INVALID_HANDLE); Assert(!(ASMAtomicReadU64(&pThis->u64State) & (RTSEMXROADS_CNT_NS_MASK | RTSEMXROADS_CNT_EW_MASK))); /* * Invalidate the object and free up the resources. */ AssertReturn(ASMAtomicCmpXchgU32(&pThis->u32Magic, RTSEMXROADS_MAGIC_DEAD, RTSEMXROADS_MAGIC), VERR_INVALID_HANDLE); RTSEMEVENTMULTI hEvt; ASMAtomicXchgHandle(&pThis->aDirs[0].hEvt, NIL_RTSEMEVENTMULTI, &hEvt); int rc = RTSemEventMultiDestroy(hEvt); AssertRC(rc); ASMAtomicXchgHandle(&pThis->aDirs[1].hEvt, NIL_RTSEMEVENTMULTI, &hEvt); rc = RTSemEventMultiDestroy(hEvt); AssertRC(rc); RTMemFree(pThis); return VINF_SUCCESS; } /** * Internal worker for RTSemXRoadsNSEnter and RTSemXRoadsEWEnter. * * @returns IPRT status code. * @param pThis The semaphore instance. * @param fDir The direction. * @param uCountShift The shift count for getting the count. * @param fCountMask The mask for getting the count. * @param uWaitCountShift The shift count for getting the wait count. * @param fWaitCountMask The mask for getting the wait count. */ DECL_FORCE_INLINE(int) rtSemXRoadsEnter(RTSEMXROADSINTERNAL *pThis, uint64_t fDir, uint64_t uCountShift, uint64_t fCountMask, uint64_t uWaitCountShift, uint64_t fWaitCountMask) { uint64_t u64OldState; uint64_t u64State; u64State = ASMAtomicReadU64(&pThis->u64State); u64OldState = u64State; add_hist(u64State, u64OldState, fDir, "enter"); for (;;) { if ((u64State & RTSEMXROADS_DIR_MASK) == (fDir << RTSEMXROADS_DIR_SHIFT)) { /* It flows in the right direction, try follow it before it changes. */ uint64_t c = (u64State & fCountMask) >> uCountShift; c++; Assert(c < 8*_1K); u64State &= ~fCountMask; u64State |= c << uCountShift; if (ASMAtomicCmpXchgU64(&pThis->u64State, u64State, u64OldState)) { add_hist(u64State, u64OldState, fDir, "enter-simple"); break; } } else if ((u64State & (RTSEMXROADS_CNT_NS_MASK | RTSEMXROADS_CNT_EW_MASK)) == 0) { /* Wrong direction, but we're alone here and can simply try switch the direction. */ u64State &= ~(RTSEMXROADS_CNT_NS_MASK | RTSEMXROADS_CNT_EW_MASK | RTSEMXROADS_DIR_MASK); u64State |= (UINT64_C(1) << uCountShift) | (fDir << RTSEMXROADS_DIR_SHIFT); if (ASMAtomicCmpXchgU64(&pThis->u64State, u64State, u64OldState)) { Assert(!pThis->aDirs[fDir].fNeedReset); add_hist(u64State, u64OldState, fDir, "enter-switch"); break; } } else { /* Add ourselves to the queue and wait for the direction to change. */ uint64_t c = (u64State & fCountMask) >> uCountShift; c++; Assert(c < RTSEMXROADS_CNT_MASK / 2); uint64_t cWait = (u64State & fWaitCountMask) >> uWaitCountShift; cWait++; Assert(cWait <= c); Assert(cWait < RTSEMXROADS_CNT_MASK / 2); u64State &= ~(fCountMask | fWaitCountMask); u64State |= (c << uCountShift) | (cWait << uWaitCountShift); if (ASMAtomicCmpXchgU64(&pThis->u64State, u64State, u64OldState)) { add_hist(u64State, u64OldState, fDir, "enter-wait"); for (uint32_t iLoop = 0; ; iLoop++) { int rc = RTSemEventMultiWait(pThis->aDirs[fDir].hEvt, RT_INDEFINITE_WAIT); AssertRCReturn(rc, rc); if (pThis->u32Magic != RTSEMXROADS_MAGIC) return VERR_SEM_DESTROYED; Assert(pThis->aDirs[fDir].fNeedReset); u64State = ASMAtomicReadU64(&pThis->u64State); add_hist(u64State, u64OldState, fDir, "enter-wakeup"); if ((u64State & RTSEMXROADS_DIR_MASK) == (fDir << RTSEMXROADS_DIR_SHIFT)) break; AssertMsg(iLoop < 1, ("%u\n", iLoop)); } /* Decrement the wait count and maybe reset the semaphore (if we're last). */ for (;;) { u64OldState = u64State; cWait = (u64State & fWaitCountMask) >> uWaitCountShift; Assert(cWait > 0); cWait--; u64State &= ~fWaitCountMask; u64State |= cWait << uWaitCountShift; if (ASMAtomicCmpXchgU64(&pThis->u64State, u64State, u64OldState)) { if (cWait == 0) { if (ASMAtomicXchgBool(&pThis->aDirs[fDir].fNeedReset, false)) { add_hist(u64State, u64OldState, fDir, fDir ? "enter-reset-EW" : "enter-reset-NS"); int rc = RTSemEventMultiReset(pThis->aDirs[fDir].hEvt); AssertRCReturn(rc, rc); } else add_hist(u64State, u64OldState, fDir, "enter-dec-no-need"); } break; } u64State = ASMAtomicReadU64(&pThis->u64State); } break; } add_hist(u64State, u64OldState, fDir, "enter-wait-failed"); } if (pThis->u32Magic != RTSEMXROADS_MAGIC) return VERR_SEM_DESTROYED; ASMNopPause(); u64State = ASMAtomicReadU64(&pThis->u64State); u64OldState = u64State; } /* got it! */ Assert((ASMAtomicReadU64(&pThis->u64State) & RTSEMXROADS_DIR_MASK) == (fDir << RTSEMXROADS_DIR_SHIFT)); return VINF_SUCCESS; } /** * Internal worker for RTSemXRoadsNSLeave and RTSemXRoadsEWLeave. * * @returns IPRT status code. * @param pThis The semaphore instance. * @param fDir The direction. * @param uCountShift The shift count for getting the count. * @param fCountMask The mask for getting the count. */ DECL_FORCE_INLINE(int) rtSemXRoadsLeave(RTSEMXROADSINTERNAL *pThis, uint64_t fDir, uint64_t uCountShift, uint64_t fCountMask) { for (;;) { uint64_t u64OldState; uint64_t u64State; uint64_t c; u64State = ASMAtomicReadU64(&pThis->u64State); u64OldState = u64State; /* The direction cannot change until we've left or we'll crash. */ Assert((u64State & RTSEMXROADS_DIR_MASK) == (fDir << RTSEMXROADS_DIR_SHIFT)); c = (u64State & fCountMask) >> uCountShift; Assert(c > 0); c--; if ( c > 0 || (u64State & ((RTSEMXROADS_CNT_NS_MASK | RTSEMXROADS_CNT_EW_MASK) & ~fCountMask)) == 0) { /* We're not the last one across or there aren't any one waiting in the other direction. */ u64State &= ~fCountMask; u64State |= c << uCountShift; if (ASMAtomicCmpXchgU64(&pThis->u64State, u64State, u64OldState)) { add_hist(u64State, u64OldState, fDir, "leave-simple"); return VINF_SUCCESS; } } else { /* Reverse the direction and signal the threads in the other direction. */ u64State &= ~(fCountMask | RTSEMXROADS_DIR_MASK); u64State |= (uint64_t)!fDir << RTSEMXROADS_DIR_SHIFT; if (ASMAtomicCmpXchgU64(&pThis->u64State, u64State, u64OldState)) { add_hist(u64State, u64OldState, fDir, fDir ? "leave-signal-NS" : "leave-signal-EW"); Assert(!pThis->aDirs[!fDir].fNeedReset); ASMAtomicWriteBool(&pThis->aDirs[!fDir].fNeedReset, true); int rc = RTSemEventMultiSignal(pThis->aDirs[!fDir].hEvt); AssertRC(rc); return VINF_SUCCESS; } } ASMNopPause(); if (pThis->u32Magic != RTSEMXROADS_MAGIC) return VERR_SEM_DESTROYED; } } RTDECL(int) RTSemXRoadsNSEnter(RTSEMXROADS hXRoads) { /* * Validate input. */ RTSEMXROADSINTERNAL *pThis = hXRoads; if (pThis == NIL_RTSEMXROADS) return VINF_SUCCESS; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertReturn(pThis->u32Magic == RTSEMXROADS_MAGIC, VERR_INVALID_HANDLE); return rtSemXRoadsEnter(pThis, 0, RTSEMXROADS_CNT_NS_SHIFT, RTSEMXROADS_CNT_NS_MASK, RTSEMXROADS_WAIT_CNT_NS_SHIFT, RTSEMXROADS_WAIT_CNT_NS_MASK); } RTDECL(int) RTSemXRoadsNSLeave(RTSEMXROADS hXRoads) { /* * Validate input. */ RTSEMXROADSINTERNAL *pThis = hXRoads; if (pThis == NIL_RTSEMXROADS) return VINF_SUCCESS; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertReturn(pThis->u32Magic == RTSEMXROADS_MAGIC, VERR_INVALID_HANDLE); return rtSemXRoadsLeave(pThis, 0, RTSEMXROADS_CNT_NS_SHIFT, RTSEMXROADS_CNT_NS_MASK); } RTDECL(int) RTSemXRoadsEWEnter(RTSEMXROADS hXRoads) { /* * Validate input. */ RTSEMXROADSINTERNAL *pThis = hXRoads; if (pThis == NIL_RTSEMXROADS) return VINF_SUCCESS; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertReturn(pThis->u32Magic == RTSEMXROADS_MAGIC, VERR_INVALID_HANDLE); return rtSemXRoadsEnter(pThis, 1, RTSEMXROADS_CNT_EW_SHIFT, RTSEMXROADS_CNT_EW_MASK, RTSEMXROADS_WAIT_CNT_EW_SHIFT, RTSEMXROADS_WAIT_CNT_EW_MASK); } RTDECL(int) RTSemXRoadsEWLeave(RTSEMXROADS hXRoads) { /* * Validate input. */ RTSEMXROADSINTERNAL *pThis = hXRoads; if (pThis == NIL_RTSEMXROADS) return VINF_SUCCESS; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertReturn(pThis->u32Magic == RTSEMXROADS_MAGIC, VERR_INVALID_HANDLE); return rtSemXRoadsLeave(pThis, 1, RTSEMXROADS_CNT_EW_SHIFT, RTSEMXROADS_CNT_EW_MASK); }