From: Lee Jones <lee.jones@linaro.org>
To: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Ludovic Desroches <ludovic.desroches@microchip.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 08/10] mfd: atmel-smc: Silence comparison of unsigned expression < 0 is always false warning (W=1)
Date: Tue, 30 Jun 2020 13:10:23 +0100 [thread overview]
Message-ID: <20200630121023.GL1179328@dell> (raw)
In-Reply-To: <20200626205627.GU131826@piout.net>
On Fri, 26 Jun 2020, Alexandre Belloni wrote:
> Hi,
>
> On 25/06/2020 07:46:17+0100, Lee Jones wrote:
> > GENMASK and it's callees conduct checking to ensure the passed
> > parameters are valid. One of those checks is for '< 0'. So if an
> > unsigned value is passed, in an invalid comparison takes place.
> >
> > Judging from the current code, it looks as though 'unsigned int'
> > is the correct type to use, so simply cast these small values
> > with no chance of being false negative to signed int for
> > comparison/error checking purposes.
> >
>
> I've been thinking about that one but shouldn't the proper fix be in
> GENMASK? My understanding is that this happens because l is 0 and I
> don't think GENMASK would ever expect negative number. What about simply
> checking that h != l when l is 0?
Looks like Rikard Falkeborn recently submitted a patch to 'fix' this
issue. However, Linus slammed it, decrying that it's the warning
that's wrong, not the code. Looks like the type-limits warning might
be getting downgraded to W=2 instead (although I don't see a patch
yet).
I'm going to drop this patch.
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Lee Jones <lee.jones@linaro.org>
To: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Nicolas Ferre <nicolas.ferre@microchip.com>,
Ludovic Desroches <ludovic.desroches@microchip.com>,
Boris Brezillon <boris.brezillon@free-electrons.com>
Subject: Re: [PATCH 08/10] mfd: atmel-smc: Silence comparison of unsigned expression < 0 is always false warning (W=1)
Date: Tue, 30 Jun 2020 13:10:23 +0100 [thread overview]
Message-ID: <20200630121023.GL1179328@dell> (raw)
In-Reply-To: <20200626205627.GU131826@piout.net>
On Fri, 26 Jun 2020, Alexandre Belloni wrote:
> Hi,
>
> On 25/06/2020 07:46:17+0100, Lee Jones wrote:
> > GENMASK and it's callees conduct checking to ensure the passed
> > parameters are valid. One of those checks is for '< 0'. So if an
> > unsigned value is passed, in an invalid comparison takes place.
> >
> > Judging from the current code, it looks as though 'unsigned int'
> > is the correct type to use, so simply cast these small values
> > with no chance of being false negative to signed int for
> > comparison/error checking purposes.
> >
>
> I've been thinking about that one but shouldn't the proper fix be in
> GENMASK? My understanding is that this happens because l is 0 and I
> don't think GENMASK would ever expect negative number. What about simply
> checking that h != l when l is 0?
Looks like Rikard Falkeborn recently submitted a patch to 'fix' this
issue. However, Linus slammed it, decrying that it's the warning
that's wrong, not the code. Looks like the type-limits warning might
be getting downgraded to W=2 instead (although I don't see a patch
yet).
I'm going to drop this patch.
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog
next prev parent reply other threads:[~2020-06-30 12:12 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-25 6:46 [PATCH 00/10] Fix a bunch more W=1 warnings in MFD Lee Jones
2020-06-25 6:46 ` Lee Jones
2020-06-25 6:46 ` [PATCH 01/10] mfd: wm8350-core: Supply description wm8350_reg_{un}lock args Lee Jones
2020-06-25 6:46 ` Lee Jones
2020-06-25 6:56 ` Greg KH
2020-06-25 6:56 ` Greg KH
2020-06-25 7:13 ` Lee Jones
2020-06-25 7:13 ` Lee Jones
2020-06-25 9:45 ` Greg KH
2020-06-25 9:45 ` Greg KH
2020-06-25 13:34 ` Lee Jones
2020-06-25 13:34 ` Lee Jones
2020-06-25 13:24 ` Jonathan Corbet
2020-06-25 13:24 ` Jonathan Corbet
2020-06-25 13:38 ` Lee Jones
2020-06-25 13:38 ` Lee Jones
2020-06-25 6:46 ` [PATCH 02/10] mfd: mfd-core: Complete kerneldoc header for devm_mfd_add_devices() Lee Jones
2020-06-25 6:46 ` Lee Jones
2020-07-01 19:33 ` Sasha Levin
2020-07-01 19:33 ` Sasha Levin
2020-07-02 6:36 ` Lee Jones
2020-07-02 6:36 ` Lee Jones
2020-07-10 14:02 ` Sasha Levin
2020-07-10 14:02 ` Sasha Levin
2020-06-25 6:46 ` [PATCH 03/10] mfd: db8500-prcmu: Add description for 'reset_reason' in kerneldoc Lee Jones
2020-06-25 6:46 ` Lee Jones
2020-07-07 12:39 ` Linus Walleij
2020-07-07 12:39 ` Linus Walleij
2020-06-25 6:46 ` [PATCH 04/10] mfd: db8500-prcmu: Remove incorrect function header from .probe() function Lee Jones
2020-06-25 6:46 ` Lee Jones
2020-07-07 12:39 ` Linus Walleij
2020-07-07 12:39 ` Linus Walleij
2020-06-25 6:46 ` [PATCH 05/10] mfd: omap-usb-host: Remove invalid use of kerneldoc syntax Lee Jones
2020-06-25 6:46 ` Lee Jones
2020-06-25 6:46 ` [PATCH 06/10] mfd: omap-usb-host: Provide description for 'pdev' argument to .probe() Lee Jones
2020-06-25 6:46 ` Lee Jones
2020-06-25 6:46 ` [PATCH 07/10] mfd: omap-usb-tll: " Lee Jones
2020-06-25 6:46 ` Lee Jones
2020-06-25 6:46 ` [PATCH 08/10] mfd: atmel-smc: Silence comparison of unsigned expression < 0 is always false warning (W=1) Lee Jones
2020-06-25 6:46 ` Lee Jones
2020-06-26 20:56 ` Alexandre Belloni
2020-06-26 20:56 ` Alexandre Belloni
2020-06-30 12:10 ` Lee Jones [this message]
2020-06-30 12:10 ` Lee Jones
2020-06-25 6:46 ` [PATCH 09/10] mfd: atmel-smc: Add missing colon(s) for 'conf' arguments Lee Jones
2020-06-25 6:46 ` Lee Jones
2020-06-25 6:55 ` Greg KH
2020-06-25 6:55 ` Greg KH
2020-06-26 20:56 ` Alexandre Belloni
2020-06-26 20:56 ` Alexandre Belloni
2020-07-01 19:33 ` Sasha Levin
2020-07-01 19:33 ` Sasha Levin
2020-07-02 6:36 ` Lee Jones
2020-07-02 6:36 ` Lee Jones
2020-07-10 14:02 ` Sasha Levin
2020-07-10 14:02 ` Sasha Levin
2020-06-25 6:46 ` [PATCH 10/10] mfd: altera-sysmgr: Supply descriptions for 'np' and 'property' function args Lee Jones
2020-06-25 6:46 ` Lee Jones
2020-07-01 19:33 ` Sasha Levin
2020-07-01 19:33 ` Sasha Levin
2020-07-02 6:35 ` Lee Jones
2020-07-02 6:35 ` Lee Jones
2020-07-10 14:02 ` Sasha Levin
2020-07-10 14:02 ` Sasha Levin
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=20200630121023.GL1179328@dell \
--to=lee.jones@linaro.org \
--cc=alexandre.belloni@bootlin.com \
--cc=boris.brezillon@free-electrons.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=ludovic.desroches@microchip.com \
--cc=stable@vger.kernel.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 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.