[PATCH v2 02/14] cxl/test: Simplify fw_buf_checksum_show()

[Eric Biggers <ebiggers@kernel.org>]

First, just use sha256() instead of a sequence of sha256_init(),
sha256_update(), and sha256_final().  The result is the same.

Second, use *phN instead of open-coding the conversion of bytes to hex.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
 tools/testing/cxl/test/mem.c | 21 ++-------------------
 1 file changed, 2 insertions(+), 19 deletions(-)

diff --git a/tools/testing/cxl/test/mem.c b/tools/testing/cxl/test/mem.c
index 0f1d91f57ba34..d533481672b78 100644
--- a/tools/testing/cxl/test/mem.c
+++ b/tools/testing/cxl/test/mem.c
@@ -1826,31 +1826,14 @@ static DEVICE_ATTR_RW(security_lock);
 static ssize_t fw_buf_checksum_show(struct device *dev,
 				    struct device_attribute *attr, char *buf)
 {
 	struct cxl_mockmem_data *mdata = dev_get_drvdata(dev);
 	u8 hash[SHA256_DIGEST_SIZE];
-	unsigned char *hstr, *hptr;
-	struct sha256_state sctx;
-	ssize_t written = 0;
-	int i;
-
-	sha256_init(&sctx);
-	sha256_update(&sctx, mdata->fw, mdata->fw_size);
-	sha256_final(&sctx, hash);
-
-	hstr = kzalloc((SHA256_DIGEST_SIZE * 2) + 1, GFP_KERNEL);
-	if (!hstr)
-		return -ENOMEM;
-
-	hptr = hstr;
-	for (i = 0; i < SHA256_DIGEST_SIZE; i++)
-		hptr += sprintf(hptr, "%02x", hash[i]);
 
-	written = sysfs_emit(buf, "%s\n", hstr);
+	sha256(mdata->fw, mdata->fw_size, hash);
 
-	kfree(hstr);
-	return written;
+	return sysfs_emit(buf, "%*phN\n", SHA256_DIGEST_SIZE, hash);
 }
 
 static DEVICE_ATTR_RO(fw_buf_checksum);
 
 static ssize_t sanitize_timeout_show(struct device *dev,
-- 
2.50.0