On 5/12/20 4:39 AM, Eyal Moscovici wrote:
I was the most hesitant about this patch because of the size difference. I decided to submit it because the type is int64 which pairs better with the MAX_INT64 check and I couldn't find a concrete reason to cap the variable at MAX_INT. Do you a concrete reason? Because the max size should rerally come into effect on very fringe cases and if you are asking for a really big buffer you should know the risks.+++ b/qemu-img.c @@ -4307,7 +4307,7 @@ static int img_bench(int argc, char **argv)              int64_t sval;               sval = cvtnum(optarg); -           if (sval < 0 || sval > INT_MAX) { +           if (sval < 0) {                  error_report("Invalid buffer size specified");INT_MAX is smaller than cvtnum's check for INT64_MAX. This code change allows larger buffer sizes, which is probably not a good idea.
The commit message does not call out a change in behavior. If you are sure that you want a change in behavior, then justify that: mention that your patch specifically changes the behavior to allow larger buffers, and why that is okay. Otherwise, it looks like your patch is accidental in its behavior change, which costs reviewer time.
In this particular case, I see no reason to allow larger buffers. That is, the existing limits made sense (benchmarking anything larger than the maximum qcow2 cluster size of 2M is unlikely to produce useful results, let alone something as large as 2G, so allowing > 2G is not helping the user). So even if your commit message did a good job of explaining that the change was intentional, it is a tough sell why we need it. If all your commit is intended to do is refactoring, then it should not be changing behavior.
-- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org
