[Libreoffice-commits] core.git: include/o3tl

[Noel Grandin (via logerrit)]

 include/o3tl/cow_wrapper.hxx |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

New commits:
commit 2f343f09b4adaed1fe7286dfc8ba73bdb13eeabf
Author:     Noel Grandin <noel.grandin at collabora.co.uk>
AuthorDate: Wed Aug 4 15:58:34 2021 +0200
Commit:     Noel Grandin <noel.grandin at collabora.co.uk>
CommitDate: Wed Aug 4 18:15:00 2021 +0200

    tsan:datarace in o3tl::ThreadSafeRefCountingPolicy
    
    Because we a non-atomic read of the reference count.
    
    Which we shouldn't be doing anyway, or the ref-counting is broken.
    
    WARNING: ThreadSanitizer: data race (pid=121172)
      Read of size 4 at 0x7b100027ba38 by thread T5:
    /media/disk2/libo-san/include/o3tl/cow_wrapper.hxx:54:17
    (libvcllo.so+0x7ee40d)
    o3tl::ThreadSafeRefCountingPolicy>::release()
    /media/disk2/libo-san/include/o3tl/cow_wrapper.hxx:208:29
    (libvcllo.so+0x7ee40d)
    o3tl::ThreadSafeRefCountingPolicy>::~cow_wrapper()
    /media/disk2/libo-san/include/o3tl/cow_wrapper.hxx:260:13
    (libvcllo.so+0x7ee40d)
    /media/disk2/libo-san/vcl/source/gdi/mapmod.cxx:97:19
    (libvcllo.so+0x7ee40d)
    /media/disk2/libo-san/vcl/source/bitmap/bitmap.cxx:166:1
    (libvcllo.so+0x92b175)
    /media/disk2/libo-san/vcl/source/bitmap/alpha.cxx:49:23
    (libvcllo.so+0x946475)
    GraphicFilterImportFlags, vcl::ScopedBitmapAccess<BitmapWriteAccess,
    Bitmap, &(Bitmap::AcquireWriteAccess())>*,
    vcl::ScopedBitmapAccess<BitmapWriteAccess, AlphaMask,
    &(AlphaMask::AcquireAlphaWriteAccess())>*)
    /media/disk2/libo-san/vcl/source/filter/png/PngImageReader.cxx:383:1
    (libvcllo.so+0xb67860)
    vcl::ScopedBitmapAccess<BitmapWriteAccess, Bitmap,
    &(Bitmap::AcquireWriteAccess())>*,
    vcl::ScopedBitmapAccess<BitmapWriteAccess, AlphaMask,
    &(AlphaMask::AcquireAlphaWriteAccess())>*)
    /media/disk2/libo-san/vcl/source/filter/png/PngImageReader.cxx:479:9
    (libvcllo.so+0xb69139)
    namespace)::GraphicImportContext&)
    /media/disk2/libo-san/vcl/source/filter/graphicfilter.cxx:586:14
    (libvcllo.so+0xac3a2f)
    /media/disk2/libo-san/vcl/source/filter/graphicfilter.cxx:574:5
    (libvcllo.so+0xac3a2f)
    /media/disk2/libo-san/comphelper/source/misc/threadpool.cxx:314:9
    (libcomphelper.so+0x1480ff)
    /media/disk2/libo-san/comphelper/source/misc/threadpool.cxx:83:24
    (libcomphelper.so+0x1480ff)
    /media/disk2/libo-san/salhelper/source/thread.cxx:40:9
    (libuno_salhelpergcc3.so.3+0x5350)
    /media/disk2/libo-san/salhelper/source/thread.cxx
    (libuno_salhelpergcc3.so.3+0x53b9)
    (libuno_salhelpergcc3.so.3+0x565e)
    /media/disk2/libo-san/sal/osl/unx/thread.cxx:264:9
    (libuno_sal.so.3+0x68325)
    
    Previous atomic write of size 4 at 0x7b100027ba38 by main thread
    (mutexes: write M7453640868405680):
    /media/disk2/libo-san/include/o3tl/cow_wrapper.hxx:57:24
    (libvcllo.so+0x7eebc9)
    o3tl::ThreadSafeRefCountingPolicy>::release()
    /media/disk2/libo-san/include/o3tl/cow_wrapper.hxx:208:29
    (libvcllo.so+0x7eebc9)
    o3tl::ThreadSafeRefCountingPolicy>::operator=(o3tl::cow_wrapper<MapMode::ImplMapMode,
    o3tl::ThreadSafeRefCountingPolicy> const&)
    /media/disk2/libo-san/include/o3tl/cow_wrapper.hxx:269:13
    (libvcllo.so+0x7eebc9)
    /media/disk2/libo-san/vcl/source/gdi/mapmod.cxx:124:45
    (libvcllo.so+0x7eebc9)
    
    Change-Id: I6334b748b91bf414168c05d90fc5bd6d7dfe3dda
    Reviewed-on: https://gerrit.libreoffice.org/c/core/+/120005
    Tested-by: Jenkins
    Reviewed-by: Noel Grandin <noel.grandin at collabora.co.uk>

diff --git a/include/o3tl/cow_wrapper.hxx b/include/o3tl/cow_wrapper.hxx
index 8cc3651030fd..c05d28699259 100644
--- a/include/o3tl/cow_wrapper.hxx
+++ b/include/o3tl/cow_wrapper.hxx
@@ -51,10 +51,7 @@ namespace o3tl
         static void incrementCount( ref_count_t& rCount ) { osl_atomic_increment(&rCount); }
         static bool decrementCount( ref_count_t& rCount )
         {
-            if( rCount == 1 ) // caller is already the only/last reference
-                return false;
-            else
-                return osl_atomic_decrement(&rCount) != 0;
+            return osl_atomic_decrement(&rCount) != 0;
         }
     };