On Thu, Mar 11, 2021 at 04:49:08PM -0800, Sami Tolvanen wrote: > With CONFIG_CFI_CLANG, a callback function passed to > __kthread_queue_delayed_work from a module points to a jump table > entry defined in the module instead of the one used in the core > kernel, which breaks function address equality in this check: > > WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); > > Disable the warning when CFI and modules are enabled. > > Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx> > --- > kernel/kthread.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/kernel/kthread.c b/kernel/kthread.c > index 1578973c5740..af5fee350586 100644 > --- a/kernel/kthread.c > +++ b/kernel/kthread.c > @@ -963,7 +963,13 @@ static void __kthread_queue_delayed_work(struct kthread_worker *worker, > struct timer_list *timer = &dwork->timer; > struct kthread_work *work = &dwork->work; > > - WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); > + /* > + * With CFI, timer->function can point to a jump table entry in a module, you keep spewing this comment line that has exactly 81 characters and thus badly messes up read it with a normal termina everywhere. Maybe instead of fixing that in ever duplication hide the whole check in a well documented helper (which would have to be a macro due to the typing involved).
