lkml.org 
[lkml]   [2020]   [Jul]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 5.7 078/244] counter: 104-quad-8: Add lock guards - differential encoder
Date
From: Syed Nayyar Waris <syednwaris@gmail.com>

[ Upstream commit 708d98932893cea609386cefdfd190f757f5a61c ]

Add lock protection from race conditions to 104-quad-8 counter driver
for differential encoder status code changes. Mutex lock calls used for
protection.

Signed-off-by: Syed Nayyar Waris <syednwaris@gmail.com>
Fixes: 954ab5cc5f3e ("counter: 104-quad-8: Support Differential Encoder Cable Status")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/counter/104-quad-8.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
index aa13708c2bc30..9364dc188f8ff 100644
--- a/drivers/counter/104-quad-8.c
+++ b/drivers/counter/104-quad-8.c
@@ -1274,18 +1274,26 @@ static ssize_t quad8_signal_cable_fault_read(struct counter_device *counter,
struct counter_signal *signal,
void *private, char *buf)
{
- const struct quad8_iio *const priv = counter->priv;
+ struct quad8_iio *const priv = counter->priv;
const size_t channel_id = signal->id / 2;
- const bool disabled = !(priv->cable_fault_enable & BIT(channel_id));
+ bool disabled;
unsigned int status;
unsigned int fault;

- if (disabled)
+ mutex_lock(&priv->lock);
+
+ disabled = !(priv->cable_fault_enable & BIT(channel_id));
+
+ if (disabled) {
+ mutex_unlock(&priv->lock);
return -EINVAL;
+ }

/* Logic 0 = cable fault */
status = inb(priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS);

+ mutex_unlock(&priv->lock);
+
/* Mask respective channel and invert logic */
fault = !(status & BIT(channel_id));

@@ -1317,6 +1325,8 @@ static ssize_t quad8_signal_cable_fault_enable_write(
if (ret)
return ret;

+ mutex_lock(&priv->lock);
+
if (enable)
priv->cable_fault_enable |= BIT(channel_id);
else
@@ -1327,6 +1337,8 @@ static ssize_t quad8_signal_cable_fault_enable_write(

outb(cable_fault_enable, priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS);

+ mutex_unlock(&priv->lock);
+
return len;
}

--
2.25.1


\
 
 \ /
  Last update: 2020-07-20 18:11    [W:0.859 / U:1.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site