/**
 * Deals with the contended case in ring-3 and ring-0.
 *
 * @returns VINF_SUCCESS or VERR_SEM_DESTROYED.
 * @param   pCritSect           The critsect.
 * @param   hNativeSelf         The native thread handle.
 */
static int pdmR3R0CritSectEnterContended(PPDMCRITSECT pCritSect, RTNATIVETHREAD hNativeSelf, PCRTLOCKVALSRCPOS pSrcPos)
{
    /*
     * Start waiting.
     */
    if (ASMAtomicIncS32(&pCritSect->s.Core.cLockers) == 0)
        return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);
# ifdef IN_RING3
    STAM_COUNTER_INC(&pCritSect->s.StatContentionR3);
# else
    STAM_COUNTER_INC(&pCritSect->s.StatContentionRZLock);
# endif

    /*
     * The wait loop.
     */
    PSUPDRVSESSION  pSession    = pCritSect->s.CTX_SUFF(pVM)->pSession;
    SUPSEMEVENT     hEvent      = (SUPSEMEVENT)pCritSect->s.Core.EventSem;
# ifdef IN_RING3
#  ifdef PDMCRITSECT_STRICT
    RTTHREAD        hThreadSelf = RTThreadSelfAutoAdopt();
    int rc2 = RTLockValidatorRecExclCheckOrder(pCritSect->s.Core.pValidatorRec, hThreadSelf, pSrcPos, RT_INDEFINITE_WAIT);
    if (RT_FAILURE(rc2))
        return rc2;
#  else
    RTTHREAD        hThreadSelf = RTThreadSelf();
#  endif
# endif
    for (;;)
    {
# ifdef PDMCRITSECT_STRICT
        int rc9 = RTLockValidatorRecExclCheckBlocking(pCritSect->s.Core.pValidatorRec, hThreadSelf, pSrcPos,
                                                      !(pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NO_NESTING),
                                                      RT_INDEFINITE_WAIT, RTTHREADSTATE_CRITSECT, true);
        if (RT_FAILURE(rc9))
            return rc9;
# elif defined(IN_RING3)
        RTThreadBlocking(hThreadSelf, RTTHREADSTATE_CRITSECT, true);
# endif
        int rc = SUPSemEventWaitNoResume(pSession, hEvent, RT_INDEFINITE_WAIT);
# ifdef IN_RING3
        RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_CRITSECT);
# endif

        if (RT_UNLIKELY(pCritSect->s.Core.u32Magic != RTCRITSECT_MAGIC))
            return VERR_SEM_DESTROYED;
        if (rc == VINF_SUCCESS)
            return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);
        AssertMsg(rc == VERR_INTERRUPTED, ("rc=%Rrc\n", rc));
    }
    /* won't get here */
}
/**
 * Common worker for the debug and normal APIs.
 *
 * @retval  VINF_SUCCESS on success.
 * @retval  VERR_SEM_BUSY if the critsect was owned.
 * @retval  VERR_SEM_NESTED if nested enter on a no nesting section. (Asserted.)
 * @retval  VERR_SEM_DESTROYED if RTCritSectDelete was called while waiting.
 *
 * @param   pCritSect   The critical section.
 */
static int pdmCritSectTryEnter(PPDMCRITSECT pCritSect, PCRTLOCKVALSRCPOS pSrcPos)
{
    /*
     * If the critical section has already been destroyed, then inform the caller.
     */
    AssertMsgReturn(pCritSect->s.Core.u32Magic == RTCRITSECT_MAGIC,
                    ("%p %RX32\n", pCritSect, pCritSect->s.Core.u32Magic),
                    VERR_SEM_DESTROYED);

    /*
     * See if we're lucky.
     */
    /* NOP ... */
    if (pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NOP)
        return VINF_SUCCESS;

    RTNATIVETHREAD hNativeSelf = pdmCritSectGetNativeSelf(pCritSect);
    /* ... not owned ... */
    if (ASMAtomicCmpXchgS32(&pCritSect->s.Core.cLockers, 0, -1))
        return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);

    /* ... or nested. */
    if (pCritSect->s.Core.NativeThreadOwner == hNativeSelf)
    {
        ASMAtomicIncS32(&pCritSect->s.Core.cLockers);
        ASMAtomicIncS32(&pCritSect->s.Core.cNestings);
        Assert(pCritSect->s.Core.cNestings > 1);
        return VINF_SUCCESS;
    }

    /* no spinning */

    /*
     * Return busy.
     */
#ifdef IN_RING3
    STAM_REL_COUNTER_INC(&pCritSect->s.StatContentionR3);
#else
    STAM_REL_COUNTER_INC(&pCritSect->s.StatContentionRZLock);
#endif
    LogFlow(("PDMCritSectTryEnter: locked\n"));
    return VERR_SEM_BUSY;
}
/**
 * Common worker for the debug and normal APIs.
 *
 * @returns VINF_SUCCESS if entered successfully.
 * @returns rcBusy when encountering a busy critical section in GC/R0.
 * @returns VERR_SEM_DESTROYED if the critical section is dead.
 *
 * @param   pCritSect           The PDM critical section to enter.
 * @param   rcBusy              The status code to return when we're in GC or R0
 *                              and the section is busy.
 */
DECL_FORCE_INLINE(int) pdmCritSectEnter(PPDMCRITSECT pCritSect, int rcBusy, PCRTLOCKVALSRCPOS pSrcPos)
{
    Assert(pCritSect->s.Core.cNestings < 8);  /* useful to catch incorrect locking */
    Assert(pCritSect->s.Core.cNestings >= 0);

    /*
     * If the critical section has already been destroyed, then inform the caller.
     */
    AssertMsgReturn(pCritSect->s.Core.u32Magic == RTCRITSECT_MAGIC,
                    ("%p %RX32\n", pCritSect, pCritSect->s.Core.u32Magic),
                    VERR_SEM_DESTROYED);

    /*
     * See if we're lucky.
     */
    /* NOP ... */
    if (pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NOP)
        return VINF_SUCCESS;

    RTNATIVETHREAD hNativeSelf = pdmCritSectGetNativeSelf(pCritSect);
    /* ... not owned ... */
    if (ASMAtomicCmpXchgS32(&pCritSect->s.Core.cLockers, 0, -1))
        return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);

    /* ... or nested. */
    if (pCritSect->s.Core.NativeThreadOwner == hNativeSelf)
    {
        ASMAtomicIncS32(&pCritSect->s.Core.cLockers);
        ASMAtomicIncS32(&pCritSect->s.Core.cNestings);
        Assert(pCritSect->s.Core.cNestings > 1);
        return VINF_SUCCESS;
    }

    /*
     * Spin for a bit without incrementing the counter.
     */
    /** @todo Move this to cfgm variables since it doesn't make sense to spin on UNI
     *        cpu systems. */
    int32_t cSpinsLeft = CTX_SUFF(PDMCRITSECT_SPIN_COUNT_);
    while (cSpinsLeft-- > 0)
    {
        if (ASMAtomicCmpXchgS32(&pCritSect->s.Core.cLockers, 0, -1))
            return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);
        ASMNopPause();
        /** @todo Should use monitor/mwait on e.g. &cLockers here, possibly with a
           cli'ed pendingpreemption check up front using sti w/ instruction fusing
           for avoiding races. Hmm ... This is assuming the other party is actually
           executing code on another CPU ... which we could keep track of if we
           wanted. */
    }

#ifdef IN_RING3
    /*
     * Take the slow path.
     */
    return pdmR3R0CritSectEnterContended(pCritSect, hNativeSelf, pSrcPos);

#else
# ifdef IN_RING0
    /** @todo If preemption is disabled it means we're in VT-x/AMD-V context
     *        and would be better off switching out of that while waiting for
     *        the lock.  Several of the locks jumps back to ring-3 just to
     *        get the lock, the ring-3 code will then call the kernel to do
     *        the lock wait and when the call return it will call ring-0
     *        again and resume via in setjmp style.  Not very efficient. */
#  if 0
    if (ASMIntAreEnabled()) /** @todo this can be handled as well by changing
                             * callers not prepared for longjmp/blocking to
                             * use PDMCritSectTryEnter. */
    {
        /*
         * Leave HWACCM context while waiting if necessary.
         */
        int rc;
        if (RTThreadPreemptIsEnabled(NIL_RTTHREAD))
        {
            STAM_REL_COUNTER_ADD(&pCritSect->s.StatContentionRZLock,    1000000);
            rc = pdmR3R0CritSectEnterContended(pCritSect, hNativeSelf, pSrcPos);
        }
        else
        {
            STAM_REL_COUNTER_ADD(&pCritSect->s.StatContentionRZLock, 1000000000);
            PVM     pVM   = pCritSect->s.CTX_SUFF(pVM);
            PVMCPU  pVCpu = VMMGetCpu(pVM);
            HWACCMR0Leave(pVM, pVCpu);
            RTThreadPreemptRestore(NIL_RTTHREAD, ????);

            rc = pdmR3R0CritSectEnterContended(pCritSect, hNativeSelf, pSrcPos);

            RTThreadPreemptDisable(NIL_RTTHREAD, ????);
            HWACCMR0Enter(pVM, pVCpu);
        }
        return rc;
    }
#  else
    /*
     * We preemption hasn't been disabled, we can block here in ring-0.
     */
    if (   RTThreadPreemptIsEnabled(NIL_RTTHREAD)
        && ASMIntAreEnabled())
        return pdmR3R0CritSectEnterContended(pCritSect, hNativeSelf, pSrcPos);
#  endif
#endif /* IN_RING0 */

    STAM_REL_COUNTER_INC(&pCritSect->s.StatContentionRZLock);

    /*
     * Call ring-3 to acquire the critical section?
     */
    if (rcBusy == VINF_SUCCESS)
    {
        PVM     pVM   = pCritSect->s.CTX_SUFF(pVM); AssertPtr(pVM);
        PVMCPU  pVCpu = VMMGetCpu(pVM);             AssertPtr(pVCpu);
        return VMMRZCallRing3(pVM, pVCpu, VMMCALLRING3_PDM_CRIT_SECT_ENTER, MMHyperCCToR3(pVM, pCritSect));
    }

    /*
     * Return busy.
     */
    LogFlow(("PDMCritSectEnter: locked => R3 (%Rrc)\n", rcBusy));
    return rcBusy;
#endif /* !IN_RING3 */
}
Beispiel #4
0
/**
 * Deals with the contended case in ring-3 and ring-0.
 *
 * @retval  VINF_SUCCESS on success.
 * @retval  VERR_SEM_DESTROYED if destroyed.
 *
 * @param   pCritSect           The critsect.
 * @param   hNativeSelf         The native thread handle.
 */
static int pdmR3R0CritSectEnterContended(PPDMCRITSECT pCritSect, RTNATIVETHREAD hNativeSelf, PCRTLOCKVALSRCPOS pSrcPos)
{
    /*
     * Start waiting.
     */
    if (ASMAtomicIncS32(&pCritSect->s.Core.cLockers) == 0)
        return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);
# ifdef IN_RING3
    STAM_COUNTER_INC(&pCritSect->s.StatContentionR3);
# else
    STAM_COUNTER_INC(&pCritSect->s.StatContentionRZLock);
# endif

    /*
     * The wait loop.
     */
    PSUPDRVSESSION  pSession    = pCritSect->s.CTX_SUFF(pVM)->pSession;
    SUPSEMEVENT     hEvent      = (SUPSEMEVENT)pCritSect->s.Core.EventSem;
# ifdef IN_RING3
#  ifdef PDMCRITSECT_STRICT
    RTTHREAD        hThreadSelf = RTThreadSelfAutoAdopt();
    int rc2 = RTLockValidatorRecExclCheckOrder(pCritSect->s.Core.pValidatorRec, hThreadSelf, pSrcPos, RT_INDEFINITE_WAIT);
    if (RT_FAILURE(rc2))
        return rc2;
#  else
    RTTHREAD        hThreadSelf = RTThreadSelf();
#  endif
# endif
    for (;;)
    {
        /*
         * Do the wait.
         *
         * In ring-3 this gets cluttered by lock validation and thread state
         * maintainence.
         *
         * In ring-0 we have to deal with the possibility that the thread has
         * been signalled and the interruptible wait function returning
         * immediately.  In that case we do normal R0/RC rcBusy handling.
         */
# ifdef IN_RING3
#  ifdef PDMCRITSECT_STRICT
        int rc9 = RTLockValidatorRecExclCheckBlocking(pCritSect->s.Core.pValidatorRec, hThreadSelf, pSrcPos,
                                                      !(pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NO_NESTING),
                                                      RT_INDEFINITE_WAIT, RTTHREADSTATE_CRITSECT, true);
        if (RT_FAILURE(rc9))
            return rc9;
#  else
        RTThreadBlocking(hThreadSelf, RTTHREADSTATE_CRITSECT, true);
#  endif
        int rc = SUPSemEventWaitNoResume(pSession, hEvent, RT_INDEFINITE_WAIT);
        RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_CRITSECT);
# else  /* IN_RING0 */
        int rc = SUPSemEventWaitNoResume(pSession, hEvent, RT_INDEFINITE_WAIT);
# endif /* IN_RING0 */

        /*
         * Deal with the return code and critsect destruction.
         */
        if (RT_UNLIKELY(pCritSect->s.Core.u32Magic != RTCRITSECT_MAGIC))
            return VERR_SEM_DESTROYED;
        if (rc == VINF_SUCCESS)
            return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);
        AssertMsg(rc == VERR_INTERRUPTED, ("rc=%Rrc\n", rc));

# ifdef IN_RING0
        /* Something is pending (signal, APC, debugger, whatever), just go back
           to ring-3 so the kernel can deal with it when leaving kernel context.

           Note! We've incremented cLockers already and cannot safely decrement
                 it without creating a race with PDMCritSectLeave, resulting in
                 spurious wakeups. */
        PVM     pVM   = pCritSect->s.CTX_SUFF(pVM); AssertPtr(pVM);
        PVMCPU  pVCpu = VMMGetCpu(pVM);             AssertPtr(pVCpu);
        rc = VMMRZCallRing3(pVM, pVCpu, VMMCALLRING3_VM_R0_PREEMPT, NULL);
        AssertRC(rc);
# endif
    }
    /* won't get here */
}