linux-kernel - [PATCH 3/4] zstd: move params structure to global variable to reduce stack usage

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Date:   Mon,  3 Jun 2019 14:32:05 +0530
From:   Maninder Singh <maninder1.s@...sung.com>
To:     akpm@...ux-foundation.org, herbert@...dor.apana.org.au,
        davem@...emloft.net, keescook@...omium.org, gustavo@...eddedor.com
Cc:     joe@...ches.com, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org, a.sahrawat@...sung.com,
        pankaj.m@...sung.com, v.narang@...sung.com,
        Maninder Singh <maninder1.s@...sung.com>
Subject: [PATCH 3/4] zstd: move params structure to global variable to
 reduce  stack usage

As params structure remains same for lifetime, just initialise it
at init time and make it global variable.

Signed-off-by: Maninder Singh <maninder1.s@...sung.com>
Signed-off-by: Vaneet Narang <v.narang@...sung.com>
---
 crypto/zstd.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/crypto/zstd.c b/crypto/zstd.c
index 4e9ff22..80a9e5c 100644
--- a/crypto/zstd.c
+++ b/crypto/zstd.c
@@ -32,6 +32,8 @@ struct zstd_ctx {
 	void *dwksp;
 };
 
+static ZSTD_parameters params;
+
 static ZSTD_parameters zstd_params(void)
 {
 	return ZSTD_getParams(ZSTD_DEF_LEVEL, 0, 0);
@@ -40,8 +42,10 @@ static ZSTD_parameters zstd_params(void)
 static int zstd_comp_init(struct zstd_ctx *ctx)
 {
 	int ret = 0;
-	const ZSTD_parameters params = zstd_params();
-	const size_t wksp_size = ZSTD_CCtxWorkspaceBound(params.cParams);
+	size_t wksp_size;
+
+	params = zstd_params();
+	wksp_size = ZSTD_CCtxWorkspaceBound(params.cParams);
 
 	ctx->cwksp = vzalloc(wksp_size);
 	if (!ctx->cwksp) {
@@ -160,7 +164,6 @@ static int __zstd_compress(const u8 *src, unsigned int slen,
 {
 	size_t out_len;
 	struct zstd_ctx *zctx = ctx;
-	const ZSTD_parameters params = zstd_params();
 
 	out_len = ZSTD_compressCCtx(zctx->cctx, dst, *dlen, src, slen, &params);
 	if (ZSTD_isError(out_len))
-- 
2.7.4