linux-kernel - [PATCH v5 4/5] mtd: spi-nor: otp: simplify length check

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Message-Id: <20210604100252.9975-5-michael@walle.cc>
Date:   Fri,  4 Jun 2021 12:02:51 +0200
From:   Michael Walle <michael@...le.cc>
To:     linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Michael Walle <michael@...le.cc>,
        Pratyush Yadav <p.yadav@...com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>
Subject: [PATCH v5 4/5] mtd: spi-nor: otp: simplify length check

By moving the code around a bit, we can just check the length before
calling spi_nor_mtd_otp_range_is_locked() and drop the length check
there. This way we don't need to take the lock. This will also skip the
"*retlen = 0" assignment if the length is zero. But mtdcore already does
that for us. Thus we can drop that, too.

Signed-off-by: Michael Walle <michael@...le.cc>
---
 drivers/mtd/spi-nor/otp.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c
index 063f8fb68649..89fe52e3851a 100644
--- a/drivers/mtd/spi-nor/otp.c
+++ b/drivers/mtd/spi-nor/otp.c
@@ -256,9 +256,6 @@ static int spi_nor_mtd_otp_range_is_locked(struct spi_nor *nor, loff_t ofs,
 	unsigned int region;
 	int locked;
 
-	if (!len)
-		return 0;
-
 	/*
 	 * If any of the affected OTP regions are locked the entire range is
 	 * considered locked.
@@ -290,13 +287,16 @@ static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs,
 	if (ofs < 0 || ofs >= spi_nor_otp_size(nor))
 		return 0;
 
+	/* don't access beyond the end */
+	total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs);
+
+	if (!total_len)
+		return 0;
+
 	ret = spi_nor_lock_and_prep(nor);
 	if (ret)
 		return ret;
 
-	/* don't access beyond the end */
-	total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs);
-
 	if (is_write) {
 		ret = spi_nor_mtd_otp_range_is_locked(nor, ofs, total_len);
 		if (ret < 0) {
@@ -307,7 +307,6 @@ static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs,
 		}
 	}
 
-	*retlen = 0;
 	while (total_len) {
 		/*
 		 * The OTP regions are mapped into a contiguous area starting
-- 
2.20.1