[PATCH RESEND 2/5] mfd: twl6030-irq: Don't write garbage to interrupt mask on read failure

[<shao.mingyin@zte.com.cn>]

From: Shao Mingyin <shao.mingyin@zte.com.cn>

twl6030_interrupt_unmask() and twl6030_interrupt_mask() ignore the return
value of the twl_i2c_read_u8() that fetches the current mask value.  When
the read fails, "unmask_value"/"mask_value" hold uninitialized stack data
which is then masked/unmasked and written back to the INT_MSK_A/B/C
registers, corrupting the interrupt mask configuration of the whole PMIC.

Bail out with the read error before touching the value or writing it back.

Fixes: e8deb28ca8e2 ("mfd: Add support for twl6030 irq framework")
Signed-off-by: Shao Mingyin <shao.mingyin@zte.com.cn>
---
---
Resend: the first copy of this patch lost its final empty context
line in transit; the diff below is unchanged.
diff --git a/drivers/mfd/twl6030-irq.c b/drivers/mfd/twl6030-irq.c
index 0ca00f618d4d..1333c4e9cdd7 100644
--- a/drivers/mfd/twl6030-irq.c
+++ b/drivers/mfd/twl6030-irq.c
@@ -235,10 +235,11 @@ int twl6030_interrupt_unmask(u8 bit_mask, u8 offset)
 
 	ret = twl_i2c_read_u8(TWL_MODULE_PIH, &unmask_value,
 			REG_INT_STS_A + offset);
+	if (ret)
+		return ret;
 	unmask_value &= (~(bit_mask));
-	ret |= twl_i2c_write_u8(TWL_MODULE_PIH, unmask_value,
+	return twl_i2c_write_u8(TWL_MODULE_PIH, unmask_value,
 			REG_INT_STS_A + offset); /* unmask INT_MSK_A/B/C */
-	return ret;
 }
 EXPORT_SYMBOL(twl6030_interrupt_unmask);
 
@@ -249,10 +250,11 @@ int twl6030_interrupt_mask(u8 bit_mask, u8 offset)
 
 	ret = twl_i2c_read_u8(TWL_MODULE_PIH, &mask_value,
 			REG_INT_STS_A + offset);
+	if (ret)
+		return ret;
 	mask_value |= (bit_mask);
-	ret |= twl_i2c_write_u8(TWL_MODULE_PIH, mask_value,
+	return twl_i2c_write_u8(TWL_MODULE_PIH, mask_value,
 			REG_INT_STS_A + offset); /* mask INT_MSK_A/B/C */
-	return ret;
 }
 EXPORT_SYMBOL(twl6030_interrupt_mask);
 
-- 
2.47.0
-- 
2.47.0