/**
* 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 */
}
/**
* 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 */
}