diff mbox series

[3/3] crypto: scompress: remove memcpy if sg_nents is 1

Message ID 20240103095006.608744-4-21cnbao@gmail.com (mailing list archive)
State Changes Requested
Delegated to: Herbert Xu
Headers show
Series mm/zswap & crypto/acompress: remove a couple of memcpy | expand

Commit Message

Barry Song Jan. 3, 2024, 9:50 a.m. UTC 
From: Barry Song <v-songbaohua@oppo.com>

while sg_nents is 1 which is always true for the current kernel
as the only user - zswap is the case, we should remove two big
memcpy.

Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
---
 crypto/scompress.c | 35 ++++++++++++++++++++++++++++-------
 1 file changed, 28 insertions(+), 7 deletions(-)

Comments

Herbert Xu Jan. 25, 2024, 9:58 a.m. UTC | #1 
On Wed, Jan 03, 2024 at 10:50:06PM +1300, Barry Song wrote:
>
> +	if (dst != scratch->dst)
> +		kunmap_local(dst);

This is missing a flush_dcache_page.

It may not matter for zswap, but this is API code and needs to
work for every single case.

Thanks,
Barry Song Feb. 16, 2024, 3:49 a.m. UTC | #2 
On Thu, Jan 25, 2024 at 10:58 PM Herbert Xu <herbert@gondor.apana.org.au> wrote:
>
> On Wed, Jan 03, 2024 at 10:50:06PM +1300, Barry Song wrote:
> >
> > +     if (dst != scratch->dst)
> > +             kunmap_local(dst);
>
> This is missing a flush_dcache_page.

Thanks, Herbert!  I'd rather add flush_dcache_page()
to the below place so that we can avoid one redundant
flush for ENOSPC/ENOMEM case:

        if (!ret) {
                if (!req->dst) {
                        req->dst = sgl_alloc(req->dlen, GFP_ATOMIC, NULL);
                        if (!req->dst) {
                                ret = -ENOMEM;
                                goto out;
                        }
                } else if (req->dlen > dlen) {
                        ret = -ENOSPC;
                        goto out;
                }
                if (dst == scratch->dst) {
                        scatterwalk_map_and_copy(scratch->dst, req->dst, 0,
                                                 req->dlen, 1);
                } else {
+                        flush_dcache_page(sg_page(req->dst));
                }
        }
out:
        if (src != scratch->src)
                kunmap_local(src);
        if (dst != scratch->dst)
                kunmap_local(dst);

>
> It may not matter for zswap, but this is API code and needs to
> work for every single case.
>
> Thanks,
> --
> Email: Herbert Xu <herbert@gondor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
>

Thanks
Barry
diff mbox series

Patch

diff --git a/crypto/scompress.c b/crypto/scompress.c
index 442a82c9de7d..d1bb40ef83a2 100644
--- a/crypto/scompress.c
+++ b/crypto/scompress.c
@@ -117,6 +117,7 @@  static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
 	struct crypto_scomp *scomp = *tfm_ctx;
 	void **ctx = acomp_request_ctx(req);
 	struct scomp_scratch *scratch;
+	void *src, *dst;
 	int ret;
 
 	if (!req->src || !req->slen || req->slen > SCOMP_SCRATCH_SIZE)
@@ -131,13 +132,26 @@  static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
 	scratch = raw_cpu_ptr(&scomp_scratch);
 	spin_lock(&scratch->lock);
 
-	scatterwalk_map_and_copy(scratch->src, req->src, 0, req->slen, 0);
+	if (sg_nents(req->src) == 1) {
+		src = kmap_local_page(sg_page(req->src)) + req->src->offset;
+	} else {
+		scatterwalk_map_and_copy(scratch->src, req->src, 0,
+					 req->slen, 0);
+		src = scratch->src;
+	}
+
+	if (req->dst && sg_nents(req->dst) == 1) {
+		dst = kmap_local_page(sg_page(req->dst)) + req->dst->offset;
+	} else {
+		dst = scratch->dst;
+	}
+
 	if (dir)
-		ret = crypto_scomp_compress(scomp, scratch->src, req->slen,
-					    scratch->dst, &req->dlen, *ctx);
+		ret = crypto_scomp_compress(scomp, src, req->slen,
+					    dst, &req->dlen, *ctx);
 	else
-		ret = crypto_scomp_decompress(scomp, scratch->src, req->slen,
-					      scratch->dst, &req->dlen, *ctx);
+		ret = crypto_scomp_decompress(scomp, src, req->slen,
+					      dst, &req->dlen, *ctx);
 	if (!ret) {
 		if (!req->dst) {
 			req->dst = sgl_alloc(req->dlen, GFP_ATOMIC, NULL);
@@ -146,10 +160,17 @@  static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
 				goto out;
 			}
 		}
-		scatterwalk_map_and_copy(scratch->dst, req->dst, 0, req->dlen,
-					 1);
+		if (dst == scratch->dst) {
+			scatterwalk_map_and_copy(scratch->dst, req->dst, 0,
+						 req->dlen, 1);
+		}
 	}
 out:
+	if (src != scratch->src)
+		kunmap_local(src);
+	if (dst != scratch->dst)
+		kunmap_local(dst);
+
 	spin_unlock(&scratch->lock);
 	return ret;
 }