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From: James Hogan <james.hogan@imgtec.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: devel@driverdev.osuosl.org, andreas.dilger@intel.com,
	Chen Gang <gang.chen.5i5j@gmail.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	bergwolf@gmail.com,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	oleg.drokin@intel.com, jacques-charles.lafoucriere@cea.fr,
	jinshan.xiong@intel.com, linux-metag@vger.kernel.org
Subject: Re: [PATCH] drivers: staging: lustre: lustre: include: add "__attribute__((packed))" for the related union
Date: Tue, 21 Jan 2014 10:36:19 +0000	[thread overview]
Message-ID: <52DE4DA3.7090301@imgtec.com> (raw)
In-Reply-To: <20140120211356.GG4815@mwanda>


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Hi Dan,

On 20/01/14 21:13, Dan Carpenter wrote:
> I made a quick and dirty sparse patch to check for this.  I don't think
> I will bother trying to send it to sparse upstream, but you can if you
> want to.
> 
> It found 289 unions which might need a __packed added.  The lustre
> unions were not in my allmodconfig so they're not listed.

Thanks a lot for this, it seems to be useful. I'm adapting it to reduce
false negatives (e.g. omitting the check if the struct/union is already
packed), and I imagine it could be made to only warn about padded
unpacked structs/unions which are used as nested members of packed
structs/unions. It wouldn't catch everything but would probably catch a
lot of cases that are most likely to be genuine since they would have
been packed at the outer level for a reason.

> Perhaps there could be a command line option or a pragma so that unions
> will work in the kernel.  We don't care about linking to outside
> libraries.

We still interact with userland via structs and unions, so it would
probably have to exclude anything in uapi/.

Cheers
James


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WARNING: multiple messages have this Message-ID (diff)
From: James Hogan <james.hogan@imgtec.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Chen Gang <gang.chen.5i5j@gmail.com>,
	<devel@driverdev.osuosl.org>, <andreas.dilger@intel.com>,
	Greg KH <gregkh@linuxfoundation.org>, <bergwolf@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	<oleg.drokin@intel.com>, <jacques-charles.lafoucriere@cea.fr>,
	<jinshan.xiong@intel.com>, <linux-metag@vger.kernel.org>
Subject: Re: [PATCH] drivers: staging: lustre: lustre: include: add "__attribute__((packed))" for the related union
Date: Tue, 21 Jan 2014 10:36:19 +0000	[thread overview]
Message-ID: <52DE4DA3.7090301@imgtec.com> (raw)
In-Reply-To: <20140120211356.GG4815@mwanda>

[-- Attachment #1: Type: text/plain, Size: 1115 bytes --]

Hi Dan,

On 20/01/14 21:13, Dan Carpenter wrote:
> I made a quick and dirty sparse patch to check for this.  I don't think
> I will bother trying to send it to sparse upstream, but you can if you
> want to.
> 
> It found 289 unions which might need a __packed added.  The lustre
> unions were not in my allmodconfig so they're not listed.

Thanks a lot for this, it seems to be useful. I'm adapting it to reduce
false negatives (e.g. omitting the check if the struct/union is already
packed), and I imagine it could be made to only warn about padded
unpacked structs/unions which are used as nested members of packed
structs/unions. It wouldn't catch everything but would probably catch a
lot of cases that are most likely to be genuine since they would have
been packed at the outer level for a reason.

> Perhaps there could be a command line option or a pragma so that unions
> will work in the kernel.  We don't care about linking to outside
> libraries.

We still interact with userland via structs and unions, so it would
probably have to exclude anything in uapi/.

Cheers
James


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  reply	other threads:[~2014-01-21 10:36 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-01-18  9:50 [PATCH] drivers: staging: lustre: lustre: include: add "__attribute__((packed))" for the related union Chen Gang
2014-01-18  9:50 ` Chen Gang
2014-01-18 10:05 ` Dan Carpenter
2014-01-18 10:05   ` Dan Carpenter
2014-01-18 10:26   ` Chen Gang
2014-01-18 10:26     ` Chen Gang
2014-01-18 14:24     ` Dan Carpenter
2014-01-19 10:07       ` Chen Gang
2014-01-19 10:07         ` Chen Gang
     [not found]         ` <52DBA3D4.3090308-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2014-01-20 11:56           ` James Hogan
2014-01-20 11:56             ` James Hogan
2014-01-20 12:30             ` Dan Carpenter
2014-01-20 12:30               ` Dan Carpenter
2014-01-20 12:37               ` James Hogan
2014-01-20 12:37                 ` James Hogan
2014-01-20 12:56                 ` Dan Carpenter
2014-01-20 12:56                   ` Dan Carpenter
2014-01-20 13:01                   ` Dan Carpenter
2014-01-20 13:38                     ` James Hogan
2014-01-20 13:38                       ` James Hogan
2014-01-20 21:13                   ` Dan Carpenter
2014-01-20 21:13                     ` Dan Carpenter
2014-01-21 10:36                     ` James Hogan [this message]
2014-01-21 10:36                       ` James Hogan
2014-01-25 11:55                       ` Chen Gang
2014-01-25 11:55                         ` Chen Gang
2014-02-01 13:57                         ` Chen Gang
2014-02-01 13:57                           ` Chen Gang
2014-02-03  8:58                           ` Dan Carpenter
2014-02-03  8:58                             ` Dan Carpenter
2014-02-03 10:03                             ` Chen Gang
2014-02-03 10:03                               ` Chen Gang
     [not found]                               ` <52EF6965.6040406-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2014-02-03 11:35                                 ` Chen Gang
2014-02-03 11:35                                   ` Chen Gang
2014-02-03 10:05                             ` David Laight
2014-02-03 10:22                               ` James Hogan
2014-02-03 10:22                                 ` James Hogan
2014-02-03 10:30                                 ` Chen Gang
2014-02-03 10:30                                   ` Chen Gang
     [not found]                                 ` <52EF6DCC.6040807-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
2014-02-03 10:35                                   ` David Laight
2014-02-03 10:35                                     ` David Laight
2014-02-03 11:02                                     ` James Hogan
2014-02-03 11:02                                       ` James Hogan
2014-02-03 11:54                                       ` David Laight
2014-02-03 11:54                                         ` David Laight
     [not found]                               ` <063D6719AE5E284EB5DD2968C1650D6D0F6B772B-VkEWCZq2GCInGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
2014-02-03 10:25                                 ` Chen Gang
2014-02-03 10:25                                   ` Chen Gang

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