From: Tom Rix <trix@redhat.com>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-edac@vger.kernel.org, linux-acpi@vger.kernel.org,
linux-pm@vger.kernel.org, xen-devel@lists.xenproject.org,
linux-block@vger.kernel.org,
openipmi-developer@lists.sourceforge.net,
"open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
<linux-crypto@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
linux-power@fi.rohmeurope.com, linux-gpio@vger.kernel.org,
amd-gfx list <amd-gfx@lists.freedesktop.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
nouveau@lists.freedesktop.org,
virtualization@lists.linux-foundation.org,
spice-devel@lists.freedesktop.org, linux-iio@vger.kernel.org,
linux-amlogic@lists.infradead.org,
industrypack-devel@lists.sourceforge.net,
linux-media@vger.kernel.org, MPT-FusionLinux.pdl@broadcom.com,
linux-scsi@vger.kernel.org, linux-mtd@lists.infradead.org,
linux-can@vger.kernel.org,
Network Development <netdev@vger.kernel.org>,
intel-wired-lan@lists.osuosl.org, ath10k@lists.infradead.org,
linux-wireless <linux-wireless@vger.kernel.org>,
linux-stm32@st-md-mailman.stormreply.com, linux-nfc@lists.01.org,
linux-nvdimm <linux-nvdimm@lists.01.org>,
linux-pci@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
platform-driver-x86@vger.kernel.org,
patches@opensource.cirrus.com, storagedev@microchip.com,
devel@driverdev.osuosl.org, linux-serial@vger.kernel.org,
linux-usb@vger.kernel.org, usb-storage@lists.one-eyed-alien.net,
linux-watchdog@vger.kernel.org, ocfs2-devel@oss.oracle.com,
bpf <bpf@vger.kernel.org>,
linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org, keyrings@vger.kernel.org,
alsa-devel@alsa-project.org,
clang-built-linux <clang-built-linux@googlegroups.com>,
Greg KH <gregkh@linuxfoundation.org>,
George Burgess <gbiv@google.com>, Joe Perches <joe@perches.com>
Subject: Re: [RFC] treewide: cleanup unreachable breaks
Date: Tue, 20 Oct 2020 06:55:52 -0700 [thread overview]
Message-ID: <ca1f50d6-1005-8e3d-8d5c-98c82a704338@redhat.com> (raw)
In-Reply-To: <CAKwvOdkR_Ttfo7_JKUiZFVqr=Uh=4b05KCPCSuzwk=zaWtA2_Q@mail.gmail.com>
On 10/19/20 12:42 PM, Nick Desaulniers wrote:
> On Sat, Oct 17, 2020 at 10:43 PM Greg KH <gregkh@linuxfoundation.org> wrote:
>> On Sat, Oct 17, 2020 at 09:09:28AM -0700, trix@redhat.com wrote:
>>> From: Tom Rix <trix@redhat.com>
>>>
>>> This is a upcoming change to clean up a new warning treewide.
>>> I am wondering if the change could be one mega patch (see below) or
>>> normal patch per file about 100 patches or somewhere half way by collecting
>>> early acks.
>> Please break it up into one-patch-per-subsystem, like normal, and get it
>> merged that way.
>>
>> Sending us a patch, without even a diffstat to review, isn't going to
>> get you very far...
> Tom,
> If you're able to automate this cleanup, I suggest checking in a
> script that can be run on a directory. Then for each subsystem you
> can say in your commit "I ran scripts/fix_whatever.py on this subdir."
> Then others can help you drive the tree wide cleanup. Then we can
> enable -Wunreachable-code-break either by default, or W=2 right now
> might be a good idea.
I should have waited for Joe Perches's fixer addition to checkpatch :)
The easy fixes I did only cover about 1/2 of the problems.
Remaining are mostly nested switches, which from a complexity standpoint is bad.
>
> Ah, George (gbiv@, cc'ed), did an analysis recently of
> `-Wunreachable-code-loop-increment`, `-Wunreachable-code-break`, and
> `-Wunreachable-code-return` for Android userspace. From the review:
> ```
> Spoilers: of these, it seems useful to turn on
> -Wunreachable-code-loop-increment and -Wunreachable-code-return by
> default for Android
In my simple add-a-cflag bot, i see there are about 250
issues for -Wunreachable-code-return.
I'll see about doing this one next.
> ...
> While these conventions about always having break arguably became
> obsolete when we enabled -Wfallthrough, my sample turned up zero
> potential bugs caught by this warning, and we'd need to put a lot of
> effort into getting a clean tree. So this warning doesn't seem to be
> worth it.
> ```
> Looks like there's an order of magnitude of `-Wunreachable-code-break`
> than the other two.
>
> We probably should add all 3 to W=2 builds (wrapped in cc-option).
> I've filed https://github.com/ClangBuiltLinux/linux/issues/1180 to
> follow up on.
Yes, i think think these should be added.
Tom
next prev parent reply other threads:[~2020-10-20 13:56 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-17 16:09 [RFC] treewide: cleanup unreachable breaks trix
2020-10-17 16:24 ` Joe Perches
2020-10-17 18:21 ` [Cocci] " Julia Lawall
2020-10-17 19:00 ` Joe Perches
2020-10-17 21:01 ` Dan Williams
2020-10-18 5:43 ` Greg KH
2020-10-18 14:04 ` Tom Rix
2020-10-19 19:42 ` Nick Desaulniers
2020-10-19 23:05 ` Jason Gunthorpe
2020-10-20 14:09 ` Tom Rix
2020-10-20 8:47 ` [Ocfs2-devel] " John Haxby
2020-10-20 13:55 ` Tom Rix [this message]
2020-10-20 18:42 ` Joe Perches
2020-10-18 9:29 ` Hans de Goede
2020-10-18 18:59 ` [Ocfs2-devel] " Matthew Wilcox
2020-10-18 19:06 ` Joe Perches
2020-10-18 19:13 ` James Bottomley
2020-10-18 19:16 ` Matthew Wilcox
2020-10-18 19:17 ` James Bottomley
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=ca1f50d6-1005-8e3d-8d5c-98c82a704338@redhat.com \
--to=trix@redhat.com \
--cc=MPT-FusionLinux.pdl@broadcom.com \
--cc=alsa-devel@alsa-project.org \
--cc=amd-gfx@lists.freedesktop.org \
--cc=ath10k@lists.infradead.org \
--cc=bpf@vger.kernel.org \
--cc=clang-built-linux@googlegroups.com \
--cc=devel@driverdev.osuosl.org \
--cc=dri-devel@lists.freedesktop.org \
--cc=gbiv@google.com \
--cc=gregkh@linuxfoundation.org \
--cc=industrypack-devel@lists.sourceforge.net \
--cc=intel-wired-lan@lists.osuosl.org \
--cc=joe@perches.com \
--cc=keyrings@vger.kernel.org \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-amlogic@lists.infradead.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-block@vger.kernel.org \
--cc=linux-can@vger.kernel.org \
--cc=linux-crypto@vger.kernel.org \
--cc=linux-edac@vger.kernel.org \
--cc=linux-gpio@vger.kernel.org \
--cc=linux-iio@vger.kernel.org \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=linux-mtd@lists.infradead.org \
--cc=linux-nfc@lists.01.org \
--cc=linux-nvdimm@lists.01.org \
--cc=linux-pci@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=linux-power@fi.rohmeurope.com \
--cc=linux-samsung-soc@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=linux-serial@vger.kernel.org \
--cc=linux-stm32@st-md-mailman.stormreply.com \
--cc=linux-usb@vger.kernel.org \
--cc=linux-watchdog@vger.kernel.org \
--cc=linux-wireless@vger.kernel.org \
--cc=ndesaulniers@google.com \
--cc=netdev@vger.kernel.org \
--cc=nouveau@lists.freedesktop.org \
--cc=ocfs2-devel@oss.oracle.com \
--cc=openipmi-developer@lists.sourceforge.net \
--cc=patches@opensource.cirrus.com \
--cc=platform-driver-x86@vger.kernel.org \
--cc=spice-devel@lists.freedesktop.org \
--cc=storagedev@microchip.com \
--cc=usb-storage@lists.one-eyed-alien.net \
--cc=virtualization@lists.linux-foundation.org \
--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).