Re: [PATCH] sg: disable interrupts inside sg_copy_buffer

[Jens Axboe <jens.axboe@oracle.com>]

On Thu, Sep 11 2008, FUJITA Tomonori wrote:
> The callers of sg_copy_buffer must disable interrupts before calling
> it (since it uses kmap_atomic). Some callers use it on
> interrupt-disabled code but some need to take the trouble to disable
> interrupts just for this. No wonder they forget about it and we hit a
> bug like:
> 
> http://bugzilla.kernel.org/show_bug.cgi?id=11529
> 
> James said that it might be better to disable interrupts inside the
> function rather than risk the callers getting it wrong.
> 
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
> ---
>  lib/scatterlist.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
> 
> diff --git a/lib/scatterlist.c b/lib/scatterlist.c
> index 876ba6d..dd52cd5 100644
> --- a/lib/scatterlist.c
> +++ b/lib/scatterlist.c
> @@ -422,6 +422,9 @@ static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents,
>  {
>  	unsigned int offset = 0;
>  	struct sg_mapping_iter miter;
> +	unsigned long flags;
> +
> +	local_irq_save(flags);
>  
>  	sg_miter_start(&miter, sgl, nents, SG_MITER_ATOMIC);
>  
> @@ -442,6 +445,8 @@ static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents,
>  
>  	sg_miter_stop(&miter);
>  
> +	local_irq_restore(flags);
> +
>  	return offset;
>  }

Agreed and applied.

-- 
Jens Axboe