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Race condition in TGtk2WidgetSet (TGtkMessageQueue)

Original Reporter info from Mantis: wavebvg
  • Reporter name: Boris Glavin

Description:

In methods Lock/UnLock of TGtkMessageQueue

procedure TGtkMessageQueue.Lock;
begin
  inc(fLock);
  if fLock=1 then
    {$IFDEF USE_GTK_MAIN_OLD_ITERATION}
    EnterCriticalsection(FCritSec);
    {$ELSE}
    g_main_context_acquire(FMainContext);
    {$ENDIF}
end;

procedure TGtkMessageQueue.UnLock;
begin
  dec(fLock);
  if fLock=0 then
    {$IFDEF USE_GTK_MAIN_OLD_ITERATION}
    LeaveCriticalsection(FCritSec);
    {$ELSE}
    g_main_context_release(FMainContext);
    {$ENDIF}
end;

race status is possible

Steps to reproduce:

Execute multiple call PostMessage from another threads

Additional information:

It is possible to add critical section for solution of the problems:

procedure TGtkMessageQueue.Lock;
begin
  EnterCriticalSection(FLockCritSec);
  inc(fLock);
  if fLock=1 then
    {$IFDEF USE_GTK_MAIN_OLD_ITERATION}
    EnterCriticalsection(FCritSec);
    {$ELSE}
    g_main_context_acquire(FMainContext);
    {$ENDIF}
  LeaveCriticalSection(FLockCritSec);
end;

procedure TGtkMessageQueue.UnLock;
begin
  EnterCriticalSection(FLockCritSec);
  dec(fLock);
  if fLock=0 then
    {$IFDEF USE_GTK_MAIN_OLD_ITERATION}
    LeaveCriticalsection(FCritSec);
    {$ELSE}
    g_main_context_release(FMainContext);
    {$ENDIF}
  LeaveCriticalSection(FLockCritSec);
end;

Mantis conversion info:

  • Mantis ID: 35395
  • OS: All
  • OS Build: All
  • Platform: Linux
  • Version: 2.1 (SVN)
  • Fixed in version: 2.0.4
  • Fixed in revision: r61026 (#e98b6c75), r62219 (#4b89d0b0)
  • Monitored by: » Cyrax (Cyrax)