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Don't use a condition variable for blocking the system profiler thread, since

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that causes a locking order reversal (condition variable lock <-> system
profiler lock) and thus a potential deadlock. Instead we use the thread
blocking API directly. Fixes #5229.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35003 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Ingo Weinhold 2010-01-11 02:33:10 +00:00
parent 83de0ccdec
commit 8fc761bd7a
1 changed files with 20 additions and 20 deletions
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40
src/system/kernel/debug/system_profiler.cpp
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@ -1,5 +1,5 @@
/*
* Copyright 2009, Ingo Weinhold, ingo_weinhold@gmx.de.
* Copyright 2009-2010, Ingo Weinhold, ingo_weinhold@gmx.de.
* Distributed under the terms of the MIT License.
*/
@ -200,8 +200,7 @@ private:
bool fIONotificationsEnabled;
bool fSchedulerNotificationsRequested;
bool fWaitObjectNotificationsRequested;
ConditionVariable fProfilerWaitCondition;
bool fProfilerWaiting;
struct thread* volatile fWaitingProfilerThread;
bool fProfilingActive;
bool fReentered[B_MAX_CPU_COUNT];
CPUProfileData fCPUData[B_MAX_CPU_COUNT];
@ -218,11 +217,11 @@ inline void
SystemProfiler::_MaybeNotifyProfilerThreadLocked()
{
// If the buffer is full enough, notify the profiler.
if (fProfilerWaiting && fBufferSize > fBufferCapacity / 2) {
fProfilerWaiting = false;
if (fWaitingProfilerThread != NULL && fBufferSize > fBufferCapacity / 2) {
int cpu = smp_get_current_cpu();
fReentered[cpu] = true;
fProfilerWaitCondition.NotifyOne(true);
thread_unblock_locked(fWaitingProfilerThread, B_OK);
fWaitingProfilerThread = NULL;
fReentered[cpu] = false;
}
}
@ -231,7 +230,7 @@ SystemProfiler::_MaybeNotifyProfilerThreadLocked()
inline void
SystemProfiler::_MaybeNotifyProfilerThread()
{
if (!fProfilerWaiting)
if (fWaitingProfilerThread == NULL)
return;
InterruptsSpinLocker threadsLocker(gThreadSpinlock);
@ -267,7 +266,7 @@ SystemProfiler::SystemProfiler(team_id team, const area_info& userAreaInfo,
fIONotificationsEnabled(false),
fSchedulerNotificationsRequested(false),
fWaitObjectNotificationsRequested(false),
fProfilerWaiting(false),
fWaitingProfilerThread(NULL),
fWaitObjectBuffer(NULL),
fWaitObjectCount(0),
fUsedWaitObjects(),
@ -275,7 +274,6 @@ SystemProfiler::SystemProfiler(team_id team, const area_info& userAreaInfo,
fWaitObjectTable()
{
B_INITIALIZE_SPINLOCK(&fLock);
fProfilerWaitCondition.Init(this, "system profiler");
memset(fReentered, 0, sizeof(fReentered));
@ -296,9 +294,9 @@ SystemProfiler::~SystemProfiler()
// Wake up the user thread, if it is waiting, and mark profiling
// inactive.
InterruptsSpinLocker locker(fLock);
if (fProfilerWaiting) {
fProfilerWaiting = false;
fProfilerWaitCondition.NotifyAll();
if (fWaitingProfilerThread != NULL) {
thread_unblock_locked(fWaitingProfilerThread, B_OK);
fWaitingProfilerThread = NULL;
}
fProfilingActive = false;
locker.Unlock();
@ -527,8 +525,10 @@ SystemProfiler::NextBuffer(size_t bytesRead, uint64* _droppedEvents)
{
InterruptsSpinLocker locker(fLock);
if (fProfilerWaiting || !fProfilingActive || bytesRead > fBufferSize)
if (fWaitingProfilerThread != NULL || !fProfilingActive
|| bytesRead > fBufferSize) {
return B_BAD_VALUE;
}
fBufferSize -= bytesRead;
fBufferStart += bytesRead;
@ -543,24 +543,24 @@ SystemProfiler::NextBuffer(size_t bytesRead, uint64* _droppedEvents)
// Wait until the buffer gets too full or an error or a timeout occurs.
while (true) {
ConditionVariableEntry waitEntry;
fProfilerWaitCondition.Add(&waitEntry);
struct thread* thread = thread_get_current_thread();
fWaitingProfilerThread = thread;
fProfilerWaiting = true;
thread_prepare_to_block(thread, B_CAN_INTERRUPT,
THREAD_BLOCK_TYPE_OTHER, "system profiler buffer");
locker.Unlock();
status_t error = waitEntry.Wait(
B_CAN_INTERRUPT | B_RELATIVE_TIMEOUT, 1000000);
status_t error = thread_block_with_timeout(B_RELATIVE_TIMEOUT, 1000000);
locker.Lock();
if (error == B_OK) {
// the caller has unset fProfilerWaiting for us
// the caller has unset fWaitingProfilerThread for us
break;
}
fProfilerWaiting = false;
fWaitingProfilerThread = NULL;
if (error != B_TIMED_OUT)
return error;