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From:   Ferdinand Blomqvist <ferdinand.blomqvist@gmail.com>
To:     linux-kernel@vger.kernel.org
Cc:     Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH v2 5/7] rslib: Fix handling of of caller provided syndrome
Date:   Thu, 20 Jun 2019 17:10:37 +0300
Message-Id: <20190620141039.9874-6-ferdinand.blomqvist@gmail.com>
In-Reply-To: <20190620141039.9874-1-ferdinand.blomqvist@gmail.com>
References: <20190620141039.9874-1-ferdinand.blomqvist@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Check if the syndrome provided by the caller is zero, and act
accordingly.

Signed-off-by: Ferdinand Blomqvist <ferdinand.blomqvist@gmail.com>
---
 lib/reed_solomon/decode_rs.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/lib/reed_solomon/decode_rs.c b/lib/reed_solomon/decode_rs.c
index 78629bbe6590..b7264a712d46 100644
--- a/lib/reed_solomon/decode_rs.c
+++ b/lib/reed_solomon/decode_rs.c
@@ -42,8 +42,18 @@
 	BUG_ON(pad < 0 || pad >= nn - nroots);
 
 	/* Does the caller provide the syndrome ? */
-	if (s != NULL)
-		goto decode;
+	if (s != NULL) {
+		for (i = 0; i < nroots; i++) {
+			/* The syndrome is in index form,
+			 * so nn represents zero
+			 */
+			if (s[i] != nn)
+				goto decode;
+		}
+
+		/* syndrome is zero, no errors to correct  */
+		return 0;
+	}
 
 	/* form the syndromes; i.e., evaluate data(x) at roots of
 	 * g(x) */
-- 
2.17.2