From 7c26e6ef96c95105d6b1dc828902067df9b0f076 Mon Sep 17 00:00:00 2001
From: Fenghua Yu <fenghua.yu@intel.com>
Date: Fri, 20 Dec 2019 16:05:55 -0800
Subject: [PATCH] mtd: rawnand: fsmc: Change to non-atomic bit operations
No need to use expensive atomic change_bit() on dat[] and err_idx[]:
1. fsmc_bch8_correct_data() is called while mutex chip->lock is held
2. err_idx[] is a local variable.
To avoid big endian concern due to type cast to unsigned long, directly
change the bit in the specified byte instead of using non-atomic
__change_bit().
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/1576886755-9788-1-git-send-email-fenghua.yu@intel.com
---
drivers/mtd/nand/raw/fsmc_nand.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/mtd/nand/raw/fsmc_nand.c b/drivers/mtd/nand/raw/fsmc_nand.c
index a6964feeec77..7e28311dffcb 100644
--- a/drivers/mtd/nand/raw/fsmc_nand.c
+++ b/drivers/mtd/nand/raw/fsmc_nand.c
@@ -809,11 +809,12 @@ static int fsmc_bch8_correct_data(struct nand_chip *chip, u8 *dat,
i = 0;
while (num_err--) {
- change_bit(0, (unsigned long *)&err_idx[i]);
- change_bit(1, (unsigned long *)&err_idx[i]);
+ err_idx[i] ^= 3;
if (err_idx[i] < chip->ecc.size * 8) {
- change_bit(err_idx[i], (unsigned long *)dat);
+ int err = err_idx[i];
+
+ dat[err >> 3] ^= BIT(err & 7);
i++;
}
}