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SubjectRe: cdrom: use kmalloced buffers instead of buffers on stack
Linux Kernel Mailing List wrote:
> Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=22a9189fd073db3d03a4cf8b8c098aa207602de1
> Commit: 22a9189fd073db3d03a4cf8b8c098aa207602de1
> Parent: 0a0c4114df4a6903bccb65b06cabb6ddc968f877
> Author: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> AuthorDate: Wed Mar 26 12:09:38 2008 +0100
> Committer: Jens Axboe <jens.axboe@oracle.com>
> CommitDate: Mon Apr 21 09:50:08 2008 +0200
>
> cdrom: use kmalloced buffers instead of buffers on stack
>
> If cdrom commands are issued to a scsi drive in most cases the buffer will be
> filled via dma. This leads to bad stack corruption on non coherent platforms,
> because the buffers are neither cache line aligned nor is the size a multiple
> of the cache line size. Using kmalloced buffers avoids this.
>
> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
> ---
> drivers/cdrom/cdrom.c | 274 ++++++++++++++++++++++++++++++++-----------------
> 1 files changed, 181 insertions(+), 93 deletions(-)

Eh... AFAICS this is only really useful in two of the cases converted.

For all the other cases (<= 32 bytes), it is _far_ less complex, far
less code to simply communicate the additional alignment requirements to
the compiler.

What about __attribute__ __aligned__? Was that tried?

Jeff




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