crypto: ablk_helper - Fix cryptd reordering

This patch fixes an old bug where requests can be reordered because
some are processed by cryptd while others are processed directly
in softirq context.

The fix is to always postpone to cryptd if there are currently
requests outstanding from the same tfm.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/ablk_helper.c

@@ -71,7 +71,8 @@ int ablk_encrypt(struct ablkcipher_request *req)
 	struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req);
 	struct async_helper_ctx *ctx = crypto_ablkcipher_ctx(tfm);
 
-	if (!may_use_simd()) {
+	if (!may_use_simd() ||
+	    (in_atomic() && cryptd_ablkcipher_queued(ctx->cryptd_tfm))) {
 		struct ablkcipher_request *cryptd_req =
 			ablkcipher_request_ctx(req);
 
@@ -90,7 +91,8 @@ int ablk_decrypt(struct ablkcipher_request *req)
 	struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req);
 	struct async_helper_ctx *ctx = crypto_ablkcipher_ctx(tfm);
 
-	if (!may_use_simd()) {
+	if (!may_use_simd() ||
+	    (in_atomic() && cryptd_ablkcipher_queued(ctx->cryptd_tfm))) {
 		struct ablkcipher_request *cryptd_req =
 			ablkcipher_request_ctx(req);