From: Logan Gunthorpe Subject: Re: [PATCH v2 07/21] crypto: shash, caam: Make use of the new sg_map helper function Date: Thu, 27 Apr 2017 09:45:57 -0600 Message-ID: <94123cbf-3287-f05e-7267-0bcf08ab0a8b@deltatee.com> References: <1493144468-22493-1-git-send-email-logang@deltatee.com> <1493144468-22493-8-git-send-email-logang@deltatee.com> <20170427035603.GA32212@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, target-devel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Christoph Hellwig , devel-gWbeCf7V1WCQmaza687I9mD2FQJk+8+b@public.gmane.org, "James E.J. Bottomley" , linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Sumit Semwal , open-iscsi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, intel-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, sparmaintainer-GLv8BlqOqDDQT0dZR+AlfA@public.gmane.org, linux-raid-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, megaraidlinux.pdl-dY08KVG/lbpWk0Htik3J/w@public.gmane.org, Jens Axboe , "Martin K. Petersen" , netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Matthew Wilcox , linux-mmc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-crypto-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Greg Kroah-Hartman , "David S. Miller" To: Herbert Xu Return-path: In-Reply-To: <20170427035603.GA32212-lOAM2aK0SrRLBo1qDEOMRrpzq4S04n8Q@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" List-Id: linux-crypto.vger.kernel.org On 26/04/17 09:56 PM, Herbert Xu wrote: > On Tue, Apr 25, 2017 at 12:20:54PM -0600, Logan Gunthorpe wrote: >> Very straightforward conversion to the new function in the caam driver >> and shash library. >> >> Signed-off-by: Logan Gunthorpe >> Cc: Herbert Xu >> Cc: "David S. Miller" >> --- >> crypto/shash.c | 9 ++++++--- >> drivers/crypto/caam/caamalg.c | 8 +++----- >> 2 files changed, 9 insertions(+), 8 deletions(-) >> >> diff --git a/crypto/shash.c b/crypto/shash.c >> index 5e31c8d..5914881 100644 >> --- a/crypto/shash.c >> +++ b/crypto/shash.c >> @@ -283,10 +283,13 @@ int shash_ahash_digest(struct ahash_request *req, struct shash_desc *desc) >> if (nbytes < min(sg->length, ((unsigned int)(PAGE_SIZE)) - offset)) { >> void *data; >> >> - data = kmap_atomic(sg_page(sg)); >> - err = crypto_shash_digest(desc, data + offset, nbytes, >> + data = sg_map(sg, 0, SG_KMAP_ATOMIC); >> + if (IS_ERR(data)) >> + return PTR_ERR(data); >> + >> + err = crypto_shash_digest(desc, data, nbytes, >> req->result); >> - kunmap_atomic(data); >> + sg_unmap(sg, data, 0, SG_KMAP_ATOMIC); >> crypto_yield(desc->flags); >> } else >> err = crypto_shash_init(desc) ?: > > Nack. This is an optimisation for the special case of a single > SG list entry. In fact in the common case the kmap_atomic should > disappear altogether in the no-highmem case. So replacing it > with sg_map is not acceptable. What you seem to have missed is that sg_map is just a thin wrapper around kmap_atomic. Perhaps with a future check for a mappable page. This change should have zero impact on performance. Logan