From: Mike Rapoport <rppt@linux.ibm.com>
To: "Ruhl, Michael J" <michael.j.ruhl@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
Chris Wilson <chris@chris-wilson.co.uk>
Subject: Re: [PATCH] io-mapping: Indicate mapping failure
Date: Tue, 21 Jul 2020 18:06:52 +0300 [thread overview]
Message-ID: <20200721150652.GI802087@linux.ibm.com> (raw)
In-Reply-To: <14063C7AD467DE4B82DEDB5C278E866301245DF505@FMSMSX108.amr.corp.intel.com>
On Tue, Jul 21, 2020 at 03:00:41PM +0000, Ruhl, Michael J wrote:
> >-----Original Message-----
> >From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> >Sent: Tuesday, July 21, 2020 10:47 AM
> >To: Ruhl, Michael J <michael.j.ruhl@intel.com>
> >Cc: dri-devel@lists.freedesktop.org; Andrew Morton <akpm@linux-
> >foundation.org>; Mike Rapoport <rppt@linux.ibm.com>; Chris Wilson
> ><chris@chris-wilson.co.uk>; stable@vger.kernel.org
> >Subject: Re: [PATCH] io-mapping: Indicate mapping failure
> >
> >On Tue, Jul 21, 2020 at 10:16:41AM -0400, Michael J. Ruhl wrote:
> >> Sometimes it is good to know when your mapping failed.
I was going to say it's always a good idea ;-)
> >Can you elaborate...
>
> Sure, guess I was too glib. 😊
>
> Currently the io_mapping_init_wc (the !ATOMIC_IOMAP version), function will
> always return success.
>
> If the setting of the iomem (from ioremap_wc) fails, the only way for the
> caller to know is to check the value of iomap->iomem.
>
> Since all of the callers expect a NULL return on error, and check for a NULL,
> I felt this needed a fixes (i.e. unexpected behavior).
>
> >> Fixes: cafaf14a5d8f ("io-mapping: Always create a struct to hold metadata
> >about the io-mapping"
> >
> >...especially taking into account that Fixes implies regression / bug?
>
> The failure (in my case a crash) is not revealed until the address is accessed
> long after the init.
>
> I will update the commit.
>
> Mike
>
> >--
> >With Best Regards,
> >Andy Shevchenko
> >
>
--
Sincerely yours,
Mike.
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dri-devel@lists.freedesktop.org
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WARNING: multiple messages have this Message-ID (diff)
From: Mike Rapoport <rppt@linux.ibm.com>
To: "Ruhl, Michael J" <michael.j.ruhl@intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
Andrew Morton <akpm@linux-foundation.org>,
Chris Wilson <chris@chris-wilson.co.uk>,
"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH] io-mapping: Indicate mapping failure
Date: Tue, 21 Jul 2020 18:06:52 +0300 [thread overview]
Message-ID: <20200721150652.GI802087@linux.ibm.com> (raw)
In-Reply-To: <14063C7AD467DE4B82DEDB5C278E866301245DF505@FMSMSX108.amr.corp.intel.com>
On Tue, Jul 21, 2020 at 03:00:41PM +0000, Ruhl, Michael J wrote:
> >-----Original Message-----
> >From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> >Sent: Tuesday, July 21, 2020 10:47 AM
> >To: Ruhl, Michael J <michael.j.ruhl@intel.com>
> >Cc: dri-devel@lists.freedesktop.org; Andrew Morton <akpm@linux-
> >foundation.org>; Mike Rapoport <rppt@linux.ibm.com>; Chris Wilson
> ><chris@chris-wilson.co.uk>; stable@vger.kernel.org
> >Subject: Re: [PATCH] io-mapping: Indicate mapping failure
> >
> >On Tue, Jul 21, 2020 at 10:16:41AM -0400, Michael J. Ruhl wrote:
> >> Sometimes it is good to know when your mapping failed.
I was going to say it's always a good idea ;-)
> >Can you elaborate...
>
> Sure, guess I was too glib. 😊
>
> Currently the io_mapping_init_wc (the !ATOMIC_IOMAP version), function will
> always return success.
>
> If the setting of the iomem (from ioremap_wc) fails, the only way for the
> caller to know is to check the value of iomap->iomem.
>
> Since all of the callers expect a NULL return on error, and check for a NULL,
> I felt this needed a fixes (i.e. unexpected behavior).
>
> >> Fixes: cafaf14a5d8f ("io-mapping: Always create a struct to hold metadata
> >about the io-mapping"
> >
> >...especially taking into account that Fixes implies regression / bug?
>
> The failure (in my case a crash) is not revealed until the address is accessed
> long after the init.
>
> I will update the commit.
>
> Mike
>
> >--
> >With Best Regards,
> >Andy Shevchenko
> >
>
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2020-07-22 7:03 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-21 14:16 io-mapping: Indicate mapping failure Michael J. Ruhl
2020-07-21 14:16 ` [PATCH] " Michael J. Ruhl
2020-07-21 14:16 ` Michael J. Ruhl
2020-07-21 14:47 ` Andy Shevchenko
2020-07-21 14:47 ` Andy Shevchenko
2020-07-21 15:00 ` Ruhl, Michael J
2020-07-21 15:00 ` Ruhl, Michael J
2020-07-21 15:06 ` Mike Rapoport [this message]
2020-07-21 15:06 ` Mike Rapoport
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