From: Zoltan Kiss <zoltan.kiss@citrix.com>
To: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
Wei Liu <wei.liu2@citrix.com>,
Ian Campbell <Ian.Campbell@citrix.com>
Subject: RING_HAS_UNCONSUMED_REQUESTS oddness
Date: Thu, 6 Mar 2014 15:47:08 +0000 [thread overview]
Message-ID: <5318987C.3030303@citrix.com> (raw)
Hi,
I was wondering for a while why this macro looks like this:
#define RING_HAS_UNCONSUMED_REQUESTS(_r) \
({ \
unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \
unsigned int rsp = RING_SIZE(_r) - \
((_r)->req_cons - (_r)->rsp_prod_pvt); \
req < rsp ? req : rsp; \
})
I would expect to check prod - cons, like RING_HAS_UNCONSUMED_RESPONSES does:
#define RING_HAS_UNCONSUMED_RESPONSES(_r) \
((_r)->sring->rsp_prod - (_r)->rsp_cons)
By my understanding, there is no way rsp could be smaller than req, so
there is no point having this. Am I missing something?
Regards,
Zoli
next reply other threads:[~2014-03-06 15:47 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-06 15:47 Zoltan Kiss [this message]
2014-03-06 15:53 ` RING_HAS_UNCONSUMED_REQUESTS oddness Ian Campbell
2014-03-06 16:31 ` Zoltan Kiss
2014-03-06 17:30 ` Tim Deegan
2014-03-06 21:39 ` Zoltan Kiss
2014-03-07 9:23 ` Paul Durrant
2014-03-07 17:43 ` Zoltan Kiss
2014-03-07 12:02 ` Wei Liu
2014-03-07 18:58 ` Zoltan Kiss
2014-03-11 15:55 ` Ian Campbell
2014-03-11 23:34 ` Zoltan Kiss
2014-03-13 16:38 ` [PATCH RFC] xen/public/ring.h: simplify RING_HAS_UNCONSUMED_REQUESTS() Tim Deegan
2014-03-22 14:18 ` Zoltan Kiss
2014-03-22 17:14 ` Tim Deegan
2014-03-24 7:38 ` Jan Beulich
2014-03-24 9:39 ` Paul Durrant
2014-03-24 9:59 ` Jan Beulich
2014-03-24 11:03 ` Paul Durrant
2014-03-24 12:23 ` Zoltan Kiss
2014-03-24 13:52 ` Paul Durrant
2014-03-24 23:55 ` Zoltan Kiss
2014-04-03 9:38 ` Tim Deegan
2014-04-03 15:34 ` Zoltan Kiss
2014-03-11 15:44 ` RING_HAS_UNCONSUMED_REQUESTS oddness Ian Campbell
2014-03-11 23:24 ` Zoltan Kiss
2014-03-12 10:28 ` Ian Campbell
2014-03-12 10:48 ` Roger Pau Monné
2014-03-12 11:25 ` Paul Durrant
2014-03-12 11:38 ` Paul Durrant
2014-03-12 14:41 ` Zoltan Kiss
2014-03-12 15:23 ` Paul Durrant
2014-03-12 15:42 ` Wei Liu
2014-03-12 15:56 ` Paul Durrant
2014-03-12 16:02 ` Paul Durrant
2014-03-12 16:13 ` Zoltan Kiss
2014-03-12 16:42 ` Paul Durrant
2014-03-12 19:06 ` Zoltan Kiss
2014-03-13 9:26 ` Paul Durrant
2014-03-13 10:02 ` Ian Campbell
2014-03-13 10:58 ` Paul Durrant
2014-03-13 12:19 ` Ian Campbell
2014-03-13 12:28 ` Zoltan Kiss
2014-03-13 12:29 ` Paul Durrant
2014-03-13 12:44 ` Ian Campbell
2014-03-12 14:25 ` Zoltan Kiss
2014-03-12 14:27 ` Zoltan Kiss
2014-03-12 14:30 ` Ian Campbell
2014-03-12 15:14 ` Zoltan Kiss
2014-03-12 15:37 ` Ian Campbell
2014-03-12 17:14 ` Zoltan Kiss
2014-03-12 17:43 ` Ian Campbell
2014-03-12 21:10 ` Zoltan Kiss
2014-03-13 10:04 ` Ian Campbell
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=5318987C.3030303@citrix.com \
--to=zoltan.kiss@citrix.com \
--cc=Ian.Campbell@citrix.com \
--cc=wei.liu2@citrix.com \
--cc=xen-devel@lists.xenproject.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).