On Mon, Jan 18, 2021 at 12:34:29PM -0800, Linus Torvalds wrote: > On Mon, Jan 18, 2021 at 11:46 AM Alexey Gladkov > <gladkov.alexey@xxxxxxxxx> wrote: > > > > Sorry about that. I thought that this code is not needed when switching > > from int to refcount_t. I was wrong. > > Well, you _may_ be right. I personally didn't check how the return > value is used. > > I only reacted to "it certainly _may_ be used, and there is absolutely > no comment anywhere about why it wouldn't matter". I have not found examples where checked the overflow after calling refcount_inc/refcount_add. For example in kernel/fork.c:2298 : current->signal->nr_threads++; atomic_inc(¤t->signal->live); refcount_inc(¤t->signal->sigcnt); $ semind search signal_struct.sigcnt def include/linux/sched/signal.h:83 refcount_t sigcnt; m-- kernel/fork.c:723 put_signal_struct if (refcount_dec_and_test(&sig->sigcnt)) m-- kernel/fork.c:1571 copy_signal refcount_set(&sig->sigcnt, 1); m-- kernel/fork.c:2298 copy_process refcount_inc(¤t->signal->sigcnt); It seems to me that the only way is to use __refcount_inc and then compare the old value with REFCOUNT_MAX Since I have not seen examples of such checks, I thought that this is acceptable. Sorry once again. I have not tried to hide these changes. -- Rgrds, legion
