linux-kernel - [PATCH 3/8] mtd: spi-nor: silently drop lock/unlock for already locked/unlocked region

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Date:	Wed, 27 Jan 2016 21:51:42 -0800
From:	Brian Norris <computersforpeace@...il.com>
To:	<linux-mtd@...ts.infradead.org>
Cc:	Brian Norris <computersforpeace@...il.com>,
	Rafał Miłecki <zajec5@...il.com>,
	Ezequiel Garcia <ezequiel@...guardiasur.com.ar>,
	Boris Brezillon <boris.brezillon@...e-electrons.com>,
	linux-kernel@...r.kernel.org, Bayi Cheng <bayi.cheng@...iatek.com>,
	Marek Vasut <marex@...x.de>, djkurtz@...omium.org
Subject: [PATCH 3/8] mtd: spi-nor: silently drop lock/unlock for already locked/unlocked region

If, for instance, the entire flash is already unlocked and I try to
mtd_unlock() the entire device, I don't expect to see an EINVAL error.
It should just silently succeed. Ditto for mtd_lock().

Signed-off-by: Brian Norris <computersforpeace@...il.com>
---
 drivers/mtd/spi-nor/spi-nor.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index c19674573eec..3a08aa53c171 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -518,8 +518,12 @@ static int stm_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 
 	status_new = (status_old & ~mask) | val;
 
+	/* Don't bother if they're the same */
+	if (status_new == status_old)
+		return 0;
+
 	/* Only modify protection if it will not unlock other areas */
-	if ((status_new & mask) <= (status_old & mask))
+	if ((status_new & mask) < (status_old & mask))
 		return -EINVAL;
 
 	write_enable(nor);
@@ -576,8 +580,12 @@ static int stm_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 
 	status_new = (status_old & ~mask) | val;
 
+	/* Don't bother if they're the same */
+	if (status_new == status_old)
+		return 0;
+
 	/* Only modify protection if it will not lock other areas */
-	if ((status_new & mask) >= (status_old & mask))
+	if ((status_new & mask) > (status_old & mask))
 		return -EINVAL;
 
 	write_enable(nor);
-- 
1.7.9.5