Re: suspicious RCU usage warning on tracing/urgent

On Mon, 11 Sep 2023 12:00:53 +0900
Masami Hiramatsu (Google) [off-list ref] wrote:

But it seems correctly taking srcu_read_lock().

    452 
    453         ei = ti->private;
    454         idx = srcu_read_lock(&eventfs_srcu);
    455         list_for_each_entry_rcu(ef, &ei->e_top_files, list) {
    456                 create_dentry(ef, dentry, false);
    457         }
    458         srcu_read_unlock(&eventfs_srcu, idx);
    459         return dcache_dir_open(inode, file);
    460 }
    461 

This may false-positive warning, or srcu_read_lock() is not enough for
list_for_each_entry_rcu(). In latter case, maybe we need to use a
mutex instead of srcu for update the ef.

Oops, that should be list_for_each_entry_srcu().

Thanks!

BTW, the ftracetest itself passed without any problem.

Thanks for testing as well!

-- Steve