tree 098ecb6e3329dd971bffe11c8564fbe30750f32d
parent 566f17fceb08a0b86b3be77cc68d7e4ffef81605
author Sungtak Lee <taklee@google.com> 1667533982 +0000
committer Cherrypicker Worker <android-build-cherrypicker-worker@google.com> 1670732865 +0000

C2BqBuffer: resolve 3 way deadlock

Do not hold lock when IPC call is expected from HAL.

C2SurfaceSyncObj is shared lock between framework and HAL. HAL process
can have only one thread to handle IPC from HAL to framework.
Therefore Holding C2SurfaceSyncObj from HAL during IPC call could
trigger deadlock. The exact scenario is as follows.

Thread #1:(HAL -> framework IPC) HIDL call onInputBuffersReleased()
            calls to feedInputBufferIfAvailable(). Since this is using
            HAL IPC thread, this will block Thread #3. This is waiting
            for mOuput mutex which is held by Thread #2.
Thread #2:(framework) discardBuffer() holds mOutput mutex which blocks
            Thread #1. But this is waiting for C2SurfaceSyncObj which is
            held by Thread #3.
Thread #3:(HAL) Dtor of C2BufferQueueBlockPoolData is holding
            C2SurfaceSyncObj, therefore this will block #2. This thread
            is waiting for HIDL IPC thread to be free in order for
            'igbp->cancel()', but HIDL IPC thread is already occupied by
            Thread #1.

Bug: 246707566
Test: atest android.media.decoder.cts.AdaptivePlaybackTest
Test: atest android.media.decoder.cts.DecoderTest
Change-Id: I6a9540d3b4d03806cd40bb4f89a234a6b77758a9
Merged-In: I6a9540d3b4d03806cd40bb4f89a234a6b77758a9
(cherry picked from commit bdd0230f54b642cf7310ddedc4589710403ed6ff)
Merged-In: I6a9540d3b4d03806cd40bb4f89a234a6b77758a9