On Mon, 9 Feb 2026 18:08:44 +0900 Masami Hiramatsu (Google) <[email protected]> wrote: > > > @@ -5152,6 +5157,9 @@ tracing_cpumask_write(struct file *filp, const char > > > __user *ubuf, > > > cpumask_var_t tracing_cpumask_new; > > > int err; > > > > > > + if (trace_array_is_readonly(tr)) > > > + return -EPERM; > > > + > > > > Shouldn't these checks be done in the open function? Doing it now is > > too late, as -EPERM on a write is confusing when the open for write > > succeeds. > > I've made a small program and straced. Surprisingly, for the super user, > open(2) does not return error on opening a readonly file with O_RDWR.
*blink* So if on open, the trace_array_is_read_only(tr) returns true and you return -EPREM, it still succeeds? That sounds like a bug! -- Steve
