From: Paolo Bonzini <pbonzini@redhat.com>
To: Gonglei <arei.gonglei@huawei.com>, Stefan Hajnoczi <stefanha@redhat.com>
Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v3] virtio-blk: trivial code optimization
Date: Tue, 10 Nov 2015 10:51:54 +0100 [thread overview]
Message-ID: <5641BE3A.4020504@redhat.com> (raw)
In-Reply-To: <56419027.8090509@huawei.com>
On 10/11/2015 07:35, Gonglei wrote:
>> > nb_sectors - int
>> > max_xfer_len - int
>> > req->qiov.size - size_t
>> > BDRV_SECTOR_SIZE - unsigned long long
>> >
>> > Therefore this expression is an int > unsigned long long comparison.
>> >
> Sorry, I'm confused.
> max_xfer_len is int,
> "req->qiov.size / BDRV_SECTOR_SIZE" is unsigned long long,
> so, "max_xfer_len - req->qiov.size / BDRV_SECTOR_SIZE" will be int,
No, the result will be unsigned long long, and the comparison is wrong
if max_xfer_len < req->qiov.size / BDRV_SECTOR_SIZE.
Paolo
> and nb_sectors is int too, so this comparison is right. Am I wrong?
>
next prev parent reply other threads:[~2015-11-10 9:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-09 9:03 [Qemu-devel] [PATCH v3] virtio-blk: trivial code optimization arei.gonglei
2015-11-09 13:28 ` Paolo Bonzini
2015-11-09 13:57 ` Stefan Hajnoczi
2015-11-10 6:35 ` Gonglei
2015-11-10 9:51 ` Paolo Bonzini [this message]
2015-11-10 9:56 ` Stefan Hajnoczi
2015-11-11 1:53 ` Gonglei
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5641BE3A.4020504@redhat.com \
--to=pbonzini@redhat.com \
--cc=arei.gonglei@huawei.com \
--cc=qemu-block@nongnu.org \
--cc=qemu-devel@nongnu.org \
--cc=stefanha@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.