Re: [PATCH] KVM: x86: fix cocci warnings

[Paolo Bonzini]

On 11/15/21 10:59, Vitaly Kuznetsov wrote:
> One minor remark: 'kvm_set_pte_rmapp()' handler is passed to
> 'kvm_handle_gfn_range()' which does
>
>          bool ret = false;
>
>          for_each_slot_rmap_range(...)
>                  ret |= handler(...);
>
> and I find '|=' to not be very natural with booleans. I'm not sure it's
> worth changing though.

Changing that would be "harder" than it seems because "ret = ret || 
handler(...)" is wrong, and "|" is even more unnatural than "|=" (so 
much that clang warns about it).

In fact I wonder if "|=" with a bool might end up warning with clang, 
which we should check before applying this patch.  It doesn't seem to be 
in the original commit[1], but better safe than sorry: Nick, does clang 
intend to warn also about "ret |= fn()" and "ret &= fn()"?  Technically, 
it is a bitwise operation with side-effects in the RHS.

Paolo

[1] https://github.com/llvm/llvm-project/commit/f59cc9542bfb461