On Wed, Dec 09, 2015 at 05:20:45PM +0200, Horia Geantă wrote:
> On 12/7/2015 9:12 PM, Russell King wrote:
> > Strictly, dma_map_sg() may coalesce SG entries, but in practise on iMX
> > hardware, this will never happen. However, dma_map_sg() can fail, and
> > we completely fail to check its return value. So, fix this properly.
> >
> > Arrange the code to map the scatterlist early, so we know how many
> > scatter table entries to allocate, and then fill them in. This allows
> > us to keep relatively simple error cleanup paths.
> >
> > Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
>
> Some tcrypt tests fail - looks like those with zero plaintext:
> caam_jr ffe301000.jr: unable to map source for DMA
> alg: hash: digest failed on test 1 for sha1-caam: ret=12
> [...]
>
> Need to be careful, dma_map_sg() returning zero is an error only if ptxt
> is not null (alternatively src_nents returned by sg_nents_for_len()
> could be checked).
>
> > @@ -1091,7 +1102,7 @@ static int ahash_digest(struct ahash_request *req)
> > u32 *sh_desc = ctx->sh_desc_digest, *desc;
> > dma_addr_t ptr = ctx->sh_desc_digest_dma;
> > int digestsize = crypto_ahash_digestsize(ahash);
> > - int src_nents, sec4_sg_bytes;
> > + int src_nents, mapped_nents, sec4_sg_bytes;
> > dma_addr_t src_dma;
> > struct ahash_edesc *edesc;
> > int ret = 0;
> > @@ -1099,9 +1110,14 @@ static int ahash_digest(struct ahash_request *req)
> > int sh_len;
> >
> > src_nents = sg_nents_for_len(req->src, req->nbytes);
> > - dma_map_sg(jrdev, req->src, src_nents, DMA_TO_DEVICE);
> > - if (src_nents > 1)
> > - sec4_sg_bytes = src_nents * sizeof(struct sec4_sg_entry);
> > + mapped_nents = dma_map_sg(jrdev, req->src, src_nents, DMA_TO_DEVICE);
> > + if (mapped_nents == 0) {
> > + dev_err(jrdev, "unable to map source for DMA\n");
> > + return -ENOMEM;
> > + }
>
> This is at least one of the places where the error condition must change
> to smth. like (src_nents != 0 && mapped_nents == 0).
I guess we should avoid calling dma_map_sg() and dma_unmap_sg() when
src_nents is zero. Thanks, I'll work that into the next patch revision.
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