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Fix races with child frame locks on Haiku

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* src/haiku_support.cc
(CHILD_FRAME_LOCK_INSIDE_LOOPER_CALLBACK): New macro.
(FrameMoved, WorkspacesChanged): Lock child frame data with that
macro instead.
This commit is contained in:
Po Lu 2022-04-14 13:14:32 +00:00
parent e5ef0fe832
commit a9b8ebf34c
1 changed files with 39 additions and 13 deletions
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52
src/haiku_support.cc
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@ -131,6 +131,29 @@ static void *grab_view = NULL;
static BLocker grab_view_locker;
static bool drag_and_drop_in_progress;
/* Many places require us to lock the child frame data, and then lock
the locker of some random window. Unfortunately, locking such a
window might be delayed due to an arriving message, which then
calls a callback inside that window that tries to lock the child
frame data but doesn't finish since the child frame lock is already
held, not letting the code that held the child frame lock proceed,
thereby causing a deadlock.
Rectifying that problem is simple: all code in a looper callback
must lock the child frame data with this macro instead.
IOW, If some other code is already running with the child frame
lock held, don't interfere: wait until it's finished before
continuing. */
#define CHILD_FRAME_LOCK_INSIDE_LOOPER_CALLBACK \
if (child_frame_lock.LockWithTimeout (200) != B_OK) \
{ \
/* The Haiku equivalent of XPutBackEvent. */ \
if (CurrentMessage ()) \
PostMessage (CurrentMessage ()); \
} \
else
/* This could be a private API, but it's used by (at least) the Qt
port, so it's probably here to stay. */
extern status_t get_subpixel_antialiasing (bool *);
@ -968,25 +991,28 @@ class EmacsWindow : public BWindow
haiku_write (MOVE_EVENT, &rq);
if (!child_frame_lock.Lock ())
gui_abort ("Failed to lock child frame state lock");
for (struct child_frame *f = subset_windows;
f; f = f->next)
DoMove (f);
child_frame_lock.Unlock ();
CHILD_FRAME_LOCK_INSIDE_LOOPER_CALLBACK
{
for (struct child_frame *f = subset_windows;
f; f = f->next)
DoMove (f);
child_frame_lock.Unlock ();
BWindow::FrameMoved (newPosition);
BWindow::FrameMoved (newPosition);
}
}
void
WorkspacesChanged (uint32_t old, uint32_t n)
{
if (!child_frame_lock.Lock ())
gui_abort ("Failed to lock child frames for changing workspaces");
for (struct child_frame *f = subset_windows;
f; f = f->next)
DoUpdateWorkspace (f);
child_frame_lock.Unlock ();
CHILD_FRAME_LOCK_INSIDE_LOOPER_CALLBACK
{
for (struct child_frame *f = subset_windows;
f; f = f->next)
DoUpdateWorkspace (f);
child_frame_lock.Unlock ();
}
}
void