[PATCH v4 7/8] hwmon: Add mutex protecting for sbtsi read/write through hwmon

[Akshay Gupta <Akshay.Gupta@amd.com>]

From: Prathima <Prathima.Lk@amd.com>

Add a mutex and take it around SBTSI read/write paths so that only
one transaction runs at a time. The lock is held only for the
duration of the bus transfer and associated driver bookkeeping, not
across blocking work unrelated to SBTSI.

This is a concurrency hardening fix.

Reviewed-by: Akshay Gupta <Akshay.Gupta@amd.com>
Signed-off-by: Prathima <Prathima.Lk@amd.com>
---
Changes since v2:
- New patch

 drivers/hwmon/sbtsi_temp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/hwmon/sbtsi_temp.c b/drivers/hwmon/sbtsi_temp.c
index d7ae986d824c..11c8108d69b2 100644
--- a/drivers/hwmon/sbtsi_temp.c
+++ b/drivers/hwmon/sbtsi_temp.c
@@ -70,6 +70,7 @@ static int sbtsi_temp_read(struct sbtsi_data *data, u8 reg1, u8 reg2,
 {
 	int ret;
 
+	guard(sbtsi)(data);
 	ret = sbtsi_xfer(data, reg1, val1, true);
 	if (!ret)
 		ret = sbtsi_xfer(data, reg2, val2, true);
@@ -84,6 +85,7 @@ static int sbtsi_temp_write(struct sbtsi_data *data, u8 reg_int, u8 reg_dec,
 {
 	int ret;
 
+	guard(sbtsi)(data);
 	ret = sbtsi_xfer(data, reg_int, &val_int, false);
 	if (!ret)
 		ret = sbtsi_xfer(data, reg_dec, &val_dec, false);
-- 
2.34.1