4c55f496d7
Posix doesn't seem to specify whether the stack of cancelled threads
is unwound, and there's nothing preventing a QThread from
terminate()ing itself, so be extra careful to drop the mutex before
calling pthread_cancel.
We can't drop the mutex in general, as that would open a window for
the following race condition:
T1 T2
t3->terminate()
lock();
read ID;
terminated = true;
unlock();
----------- t3 exits naturally -----------
t3->wait();
t4->start(); // gets ex-t3's ID
pthread_cancel(ID) // oops, cancels new t4
But we can drop it when this == currentThread(), because said window
does not exist: While this_thread is executing terminate(), it cannot
at the same time exit naturally.
As drive-by, scope a variable tighter.
Pick-to: 6.7 6.5
Change-Id: I77a628e62d88e383d5aa91cfd97440186c997fc4
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 272c0215c2058bc267abf0a247da878f652eaffa)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>