[PATCH v6 1/2] crypto: introduce: acomp_is_async to expose if comp drivers might sleep

[Barry Song <21cnbao@gmail.com>]

From: Barry Song <v-songbaohua@oppo.com>

acomp's users might want to know if acomp is really async to
optimize themselves. One typical user which can benefit from
exposed async stat is zswap.

In zswap, zsmalloc is the most commonly used allocator for
(and perhaps the only one). For zsmalloc, we cannot sleep
while we map the compressed memory, so we copy it to a
temporary buffer. By knowing the alg won't sleep can help
zswap to avoid the need for a buffer. This shows noticeable
improvement in load/store latency of zswap.

Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
---
 include/crypto/acompress.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/crypto/acompress.h b/include/crypto/acompress.h
index 574cffc90730..80e243611fe2 100644
--- a/include/crypto/acompress.h
+++ b/include/crypto/acompress.h
@@ -160,6 +160,12 @@ static inline void acomp_request_set_tfm(struct acomp_req *req,
 	req->base.tfm = crypto_acomp_tfm(tfm);
 }
 
+static inline bool acomp_is_async(struct crypto_acomp *tfm)
+{
+	return crypto_comp_alg_common(tfm)->base.cra_flags &
+	       CRYPTO_ALG_ASYNC;
+}
+
 static inline struct crypto_acomp *crypto_acomp_reqtfm(struct acomp_req *req)
 {
 	return __crypto_acomp_tfm(req->base.tfm);
-- 
2.34.1