[PATCH v3 2/4] uacce: fix isolate sysfs check condition

[Chenghai Huang <huangchenghai2@huawei.com>]

uacce supports the device isolation feature. If the driver
implements the isolate_err_threshold_read and
isolate_err_threshold_write callback functions, uacce will create
sysfs files now. Users can read and configure the isolation policy
through sysfs. Currently, sysfs files are created as long as either
isolate_err_threshold_read or isolate_err_threshold_write callback
functions are present.

However, accessing a non-existent callback function may cause the
system to crash. Therefore, check whether the function exists
before calling isolate_err_threshold_read or
isolate_err_threshold_write.

Fixes: e3e289fbc0b5 ("uacce: supports device isolation feature")
Cc: stable@vger.kernel.org
Signed-off-by: Chenghai Huang <huangchenghai2@huawei.com>
---
 drivers/misc/uacce/uacce.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
index 9b82a6731832..e3433d95640a 100644
--- a/drivers/misc/uacce/uacce.c
+++ b/drivers/misc/uacce/uacce.c
@@ -382,6 +382,9 @@ static ssize_t isolate_strategy_show(struct device *dev, struct device_attribute
 	struct uacce_device *uacce = to_uacce_device(dev);
 	u32 val;
 
+	if (!uacce->ops->isolate_err_threshold_read)
+		return -ENOENT;
+
 	val = uacce->ops->isolate_err_threshold_read(uacce);
 
 	return sysfs_emit(buf, "%u\n", val);
@@ -394,6 +397,9 @@ static ssize_t isolate_strategy_store(struct device *dev, struct device_attribut
 	unsigned long val;
 	int ret;
 
+	if (!uacce->ops->isolate_err_threshold_write)
+		return -ENOENT;
+
 	if (kstrtoul(buf, 0, &val) < 0)
 		return -EINVAL;
 
@@ -440,9 +446,7 @@ static umode_t uacce_dev_is_visible(struct kobject *kobj,
 	    (!uacce->qf_pg_num[UACCE_QFRT_DUS])))
 		return 0;
 
-	if (attr == &dev_attr_isolate_strategy.attr &&
-	    (!uacce->ops->isolate_err_threshold_read &&
-	     !uacce->ops->isolate_err_threshold_write))
+	if (attr == &dev_attr_isolate_strategy.attr)
 		return 0;
 
 	if (attr == &dev_attr_isolate.attr && !uacce->ops->get_isolate_state)
-- 
2.33.0