On Thu, 21 Nov 2024 10:18:22 +0800 Wei Li <[email protected]> wrote:
> 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. Instead of making a new parameter in trace_min_max_param, why not just change the hwlat "width" file to have its own ops. Then you can make the trace_min_max_read() non-static, reuse that, and then have the hwlat use its own write function. It would make it much more straight forward. That could be done for a fix that would be tagged as stable, and it would also be a single patch. Really, for a clean up (after that is done), the trace_min_max_fops should be replaced to get rid of the "lock" parameter. Perhaps have a trace_min_max_lock_fops. But Linus hates conditional locking, and I don't blame him. I'm trying to clean up this code with using guard()s and that conditional locking makes that not possible. -- Steve > > Signed-off-by: Wei Li <[email protected]> > --- > 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; > };
