Re: [PATCH v18 11/17] fprobe: Rewrite fprobe on function-graph tracer

Masami Hiramatsu
2024-11-09T14:55:57Z

On Fri, 1 Nov 2024 15:28:44 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Sat, 26 Oct 2024 13:37:43 +0900
> "Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:
>
> > diff --git a/include/linux/fprobe.h b/include/linux/fprobe.h
> > index ef609bcca0f9..686b30ce48b4 100644
> > --- a/include/linux/fprobe.h
> > +++ b/include/linux/fprobe.h
> > @@ -5,10 +5,11 @@
> >
> > #include <linux/compiler.h>
> > #include <linux/ftrace.h>
> > -#include <linux/rethook.h>
> > +#include <linux/rcupdate.h>
> > +#include <linux/refcount.h>
> > +#include <linux/slab.h>
> >
> > struct fprobe;
> > -
> > typedef int (*fprobe_entry_cb)(struct fprobe *fp, unsigned long entry_ip,
> > unsigned long ret_ip, struct ftrace_regs *regs,
> > void *entry_data);
> > @@ -17,35 +18,57 @@ typedef void (*fprobe_exit_cb)(struct fprobe *fp, unsigned long entry_ip,
> > unsigned long ret_ip, struct ftrace_regs *regs,
> > void *entry_data);
> >
> > +/**
> > + * strcut fprobe_hlist_node - address based hash list node for fprobe.
>
> struct
>

oops, thanks.

> > + *
> > + * @hlist: The hlist node for address search hash table.
> > + * @addr: The address represented by this.
>
> What is "this" in the above?

it should be `by this node.`

>
> > + * @fp: The fprobe which owns this.
> > + */
> > +struct fprobe_hlist_node {
> > + struct hlist_node hlist;
> > + unsigned long addr;
> > + struct fprobe *fp;
> > +};
> > +
> > +/**
> > + * struct fprobe_hlist - hash list nodes for fprobe.
> > + *
> > + * @hlist: The hlist node for existence checking hash table.
> > + * @rcu: rcu_head for RCU deferred release.
> > + * @fp: The fprobe which owns this fprobe_hlist.
> > + * @size: The size of @array.
> > + * @array: The fprobe_hlist_node for each address to probe.
> > + */
> > +struct fprobe_hlist {
> > + struct hlist_node hlist;
> > + struct rcu_head rcu;
> > + struct fprobe *fp;
> > + int size;
> > + struct fprobe_hlist_node array[];
>
> Should the above have __counted_by(size) ?

Yes. Thanks!

>
> -- Steve
>
> > +};
> > +
> > /**
> > * struct fprobe - ftrace based probe.
> > - * @ops: The ftrace_ops.
> > + *
> > * @nmissed: The counter for missing events.
> > * @flags: The status flag.
> > - * @rethook: The rethook data structure. (internal data)
> > * @entry_data_size: The private data storage size.
> > - * @nr_maxactive: The max number of active functions.
> > + * @nr_maxactive: The max number of active functions. (*deprecated)
> > * @entry_handler: The callback function for function entry.
> > * @exit_handler: The callback function for function exit.
> > + * @hlist_array: The fprobe_hlist for fprobe search from IP hash table.
> > */
> > struct fprobe {
> > -#ifdef CONFIG_FUNCTION_TRACER
> > - /*
> > - * If CONFIG_FUNCTION_TRACER is not set, CONFIG_FPROBE is disabled too.
> > - * But user of fprobe may keep embedding the struct fprobe on their own
> > - * code. To avoid build error, this will keep the fprobe data structure
> > - * defined here, but remove ftrace_ops data structure.
> > - */
> > - struct ftrace_ops ops;
> > -#endif
> > unsigned long nmissed;
> > unsigned int flags;
> > - struct rethook *rethook;
> > size_t entry_data_size;
> > int nr_maxactive;
> >
> > fprobe_entry_cb entry_handler;
> > fprobe_exit_cb exit_handler;
> > +
> > + struct fprobe_hlist *hlist_array;
> > };
> >

--
Masami Hiramatsu (Google) <mhiramat@kernel.org>