Re: [PATCH] advansys: fix overrun_buf aligned bug

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Fri, 2008-02-08 at 09:50 +0900, FUJITA Tomonori wrote:
> struct asc_dvc_var needs overrun buffer to be placed on an 8 byte
> boundary. advansys defines struct asc_dvc_var:
> 
> struct asc_dvc_var {
> 	...
> 	uchar overrun_buf[ASC_OVERRUN_BSIZE] __aligned(8);
> 
> The problem is that struct asc_dvc_var is placed on
> shost->hostdata. So if the hostdata is not on an 8 byte boundary, the
> advansys crashes. The hostdata is placed on a sizeof(unsigned long)
> boundary so the 8 byte boundary is not garanteed with x86_32.
> 
> With 2.6.23 and 2.6.24, the hostdata is on an 8 byte boundary by
> chance, but with the current git, it's not.
> 
> This patch removes overrun_buf static array and use kzalloc.

It's a bit of a waste of a kmallocs.  The usual way of fixing this type
of cockup is to float the structure until it becomes aligned, but I
suppose that involves changing all calls to shost_priv in the driver ...

James