From 13dcc7fc5f662a8c00eff5dce689c81231b5216e Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Thu, 25 Apr 2024 00:35:04 +0300 Subject: test: fence: Fix race condition The fence test is racy, as it relies on the main loop being executed between completion of request signalledRequestId_ and signalledRequestId_ + 1. This usually happens, but is not guaranteed. To fix the race condition, change the request identification logic by replacing usage of the cookie value, which is zero-based and wraps around at nbuffers_ - 1, with a completed request counter that is one-based and doesn't wrap. The completedRequestId_, expiredRequestId_ and signalledRequestId_ variables now track the identifier of the last request that has completed, the request whose fence will time out, and the request whose fence will be signalled. Signed-off-by: Laurent Pinchart Reviewed-by: Daniel Scally Reviewed-by: Kieran Bingham --- test/fence.cpp | 57 ++++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 36 insertions(+), 21 deletions(-) (limited to 'test') diff --git a/test/fence.cpp b/test/fence.cpp index c2828862..a8fba728 100644 --- a/test/fence.cpp +++ b/test/fence.cpp @@ -57,8 +57,11 @@ private: bool expectedCompletionResult_ = true; bool setFence_ = true; - unsigned int completedRequest_; - + /* + * Request IDs track the number of requests that have completed. They + * are one-based, and don't wrap. + */ + unsigned int completedRequestId_; unsigned int signalledRequestId_; unsigned int expiredRequestId_; unsigned int nbuffers_; @@ -126,8 +129,19 @@ int FenceTest::init() return TestFail; } - signalledRequestId_ = nbuffers_ - 2; - expiredRequestId_ = nbuffers_ - 1; + completedRequestId_ = 0; + + /* + * All but two requests are queued without a fence. Request + * expiredRequestId_ will be queued with a fence that we won't signal + * (which is then expected to expire), and request signalledRequestId_ + * will be queued with a fence that gets signalled. Select nbuffers_ + * and nbuffers_ * 2 for those two requests, to space them by a few + * frames while still not requiring a long time for the test to + * complete. + */ + expiredRequestId_ = nbuffers_; + signalledRequestId_ = nbuffers_ * 2; return TestPass; } @@ -189,16 +203,16 @@ void FenceTest::requestRequeue(Request *request) const Request::BufferMap &buffers = request->buffers(); const Stream *stream = buffers.begin()->first; FrameBuffer *buffer = buffers.begin()->second; - uint64_t cookie = request->cookie(); request->reuse(); - if (cookie == signalledRequestId_ && setFence_) { + if (completedRequestId_ == signalledRequestId_ - nbuffers_ && setFence_) { /* - * The second time this request is queued add a fence to it. - * - * The main loop signals it by using a timer to write to the - * efd2_ file descriptor before the fence expires. + * This is the request that will be used to test fence + * signalling when it completes next time. Add a fence to it, + * using efd2_. The main loop will signal the fence by using a + * timer to write to the efd2_ file descriptor before the fence + * expires. */ std::unique_ptr fence = std::make_unique(std::move(eventFd2_)); @@ -213,16 +227,15 @@ void FenceTest::requestRequeue(Request *request) void FenceTest::requestComplete(Request *request) { - uint64_t cookie = request->cookie(); - completedRequest_ = cookie; + completedRequestId_++; /* - * The last request is expected to fail as its fence has not been - * signaled. + * Request expiredRequestId_ is expected to fail as its fence has not + * been signalled. * * Validate the fence status but do not re-queue it. */ - if (cookie == expiredRequestId_) { + if (completedRequestId_ == expiredRequestId_) { if (validateExpiredRequest(request) != TestPass) expectedCompletionResult_ = false; @@ -230,7 +243,7 @@ void FenceTest::requestComplete(Request *request) return; } - /* Validate all requests but the last. */ + /* Validate all other requests. */ if (validateRequest(request) != TestPass) { expectedCompletionResult_ = false; @@ -271,7 +284,7 @@ int FenceTest::run() } int ret; - if (i == expiredRequestId_) { + if (i == expiredRequestId_ - 1) { /* This request will have a fence, and it will expire. */ std::unique_ptr fence = std::make_unique(std::move(eventFd_)); @@ -318,11 +331,13 @@ int FenceTest::run() Timer timer; timer.start(1000ms); while (timer.isRunning() && expectedCompletionResult_) { - if (completedRequest_ == signalledRequestId_ && setFence_) + if (completedRequestId_ == signalledRequestId_ - 1 && setFence_) /* - * signalledRequestId_ has just completed and it has - * been re-queued with a fence. Start the timer to - * signal the fence in 10 msec. + * The request just before signalledRequestId_ has just + * completed. Request signalledRequestId_ has been + * queued with a fence, and libcamera is likely already + * waiting on the fence, or will soon. Start the timer + * to signal the fence in 10 msec. */ fenceTimer.start(10ms); -- cgit v1.2.1