From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Yury Norov <yury.norov@gmail.com>
Cc: Alexander Potapenko <glider@google.com>,
catalin.marinas@arm.com, will@kernel.org, pcc@google.com,
andreyknvl@gmail.com, linux@rasmusvillemoes.dk,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, eugenis@google.com
Subject: Re: [v2 3/5] arm64: mte: implement CONFIG_ARM64_MTE_COMP
Date: Fri, 14 Jul 2023 11:01:34 +0300 [thread overview]
Message-ID: <ZLEA3oxst2FBDWhC@smile.fi.intel.com> (raw)
In-Reply-To: <ZLBQCFbBOaBUTQmB@yury-ThinkPad>
On Thu, Jul 13, 2023 at 12:27:15PM -0700, Yury Norov wrote:
...
> > > + void *storage = ea0_storage(handle);
> > > + int size = ea0_storage_size(handle);
> > > + if (!handle || !storage)
> > > + return;
> >
> > You use handle before this check. Haven't you run static analysers?
>
> This approach is called 'defensive programming' as I learned from
> previous iteration.
No, this approach called "let compiler optimize the check away". :-)
When compiler sees something like
TYPE bar = MACRO(foo); // FUNC(foo);
if (!foo)
blalblabla;
the conditional can be eliminated as the optimizer thinks the way "okay,
developer already _used_ the foo in some code, it means it can't not be NULL,
let's drop a dead code".
(Yes, I know what defensive programming means and we actually quite rarely
use it in the kernel for the internal APIs)
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2023-07-14 8:04 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-13 12:57 [v2 0/5] Implement MTE tag compression for swapped pages Alexander Potapenko
2023-07-13 12:57 ` [v2 1/5] lib/bitmap: add bitmap_{set,get}_value_unaligned() Alexander Potapenko
2023-07-13 17:28 ` Andy Shevchenko
2023-07-13 18:05 ` Alexander Potapenko
2023-07-14 8:04 ` Andy Shevchenko
2023-07-14 11:19 ` William Breathitt Gray
2023-07-14 11:28 ` Andy Shevchenko
2023-07-14 12:07 ` Alexander Potapenko
2023-07-14 12:30 ` Andy Shevchenko
2023-07-13 12:57 ` [v2 2/5] lib/test_bitmap: add tests for bitmap_{set,get}_value_unaligned Alexander Potapenko
2023-07-13 12:57 ` [v2 3/5] arm64: mte: implement CONFIG_ARM64_MTE_COMP Alexander Potapenko
2023-07-13 16:37 ` Alexander Potapenko
2023-07-13 17:23 ` Andy Shevchenko
2023-07-13 19:27 ` Yury Norov
2023-07-14 8:01 ` Andy Shevchenko [this message]
2023-07-14 9:25 ` Alexander Potapenko
2023-07-14 10:47 ` Andy Shevchenko
2023-07-14 11:17 ` Alexander Potapenko
2023-07-13 12:57 ` [v2 4/5] arm64: mte: add a test for MTE tags compression Alexander Potapenko
2023-07-13 12:57 ` [v2 5/5] arm64: mte: add compression support to mteswap.c Alexander Potapenko
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=ZLEA3oxst2FBDWhC@smile.fi.intel.com \
--to=andriy.shevchenko@linux.intel.com \
--cc=andreyknvl@gmail.com \
--cc=catalin.marinas@arm.com \
--cc=eugenis@google.com \
--cc=glider@google.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@rasmusvillemoes.dk \
--cc=pcc@google.com \
--cc=will@kernel.org \
--cc=yury.norov@gmail.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox