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

Barry Song
2024-01-03T09:50:47Z

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(-)

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;
}
--
2.34.1