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

[Wei Li]

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 <liwei...@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