[PATCH v2 1/2] tracing: Allow custom read/write processing in trace_min_max_{write,read}()

[Wei Li <liwei391@huawei.com>]

The 'trace_min_max_fops' implements a generic function to read/write u64
values from tracefs, add support of custom read/write processing to allow
special requirements.

Signed-off-by: Wei Li <liwei391@huawei.com>
---
 kernel/trace/trace.c | 13 ++++++++++---
 kernel/trace/trace.h |  2 ++
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2b64b3ec67d9..ab5ea6d7148c 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7689,8 +7689,12 @@ trace_min_max_write(struct file *filp, const char __user *ubuf, size_t cnt, loff
 	if (param->max && val > *param->max)
 		err = -EINVAL;
 
-	if (!err)
-		*param->val = val;
+	if (!err) {
+		if (unlikely(param->write))
+			param->write(param->val, val);
+		else
+			*param->val = val;
+	}
 
 	if (param->lock)
 		mutex_unlock(param->lock);
@@ -7723,7 +7727,10 @@ trace_min_max_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppo
 	if (!param)
 		return -EFAULT;
 
-	val = *param->val;
+	if (unlikely(param->read))
+		val = param->read(param->val);
+	else
+		val = *param->val;
 
 	if (cnt > sizeof(buf))
 		cnt = sizeof(buf);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index c866991b9c78..2aaf3030c466 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -2159,6 +2159,8 @@ static inline void sanitize_event_name(char *name)
 struct trace_min_max_param {
 	struct mutex	*lock;
 	u64		*val;
+	u64		(*read)(u64 *val);
+	void		(*write)(u64 *val, u64 data);
 	u64		*min;
 	u64		*max;
 };
-- 
2.25.1