On Sat, Apr 12, 2025 at 10:09 PM Steven Rostedt <rost...@goodmis.org> wrote:
>
> On Sat, 12 Apr 2025 21:33:48 +0800
> Menglong Dong <menglong8.d...@gmail.com> wrote:
>
> > The max ftrace hash bits is made fls(32) in register_ftrace_direct(),
> > which seems illogical, and it seems to be a spelling mistake.
> >
> > Just fix it.
> >
> > (Do I misunderstand something?)
>
> I think the logic is incorrect and this patch doesn't fix it.
>
> >
> > Fixes: d05cb470663a ("ftrace: Fix modification of direct_function hash
> > while in use")
> > Signed-off-by: Menglong Dong <dong...@chinatelecom.cn>
> > ---
> > kernel/trace/ftrace.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> > index 1a48aedb5255..7697605a41e6 100644
> > --- a/kernel/trace/ftrace.c
> > +++ b/kernel/trace/ftrace.c
> > @@ -5914,7 +5914,7 @@ int register_ftrace_direct(struct ftrace_ops *ops,
> > unsigned long addr)
> >
> > /* Make a copy hash to place the new and the old entries in */
> > size = hash->count + direct_functions->count;
> > - if (size > 32)
> > + if (size < 32)
> > size = 32;
> > new_hash = alloc_ftrace_hash(fls(size));
> > if (!new_hash)
>
> The above probably should be:
>
> size = hash->count + direct_functions->count
> size = fls(size);
> if (size > FTRACE_HASH_MAX_BITS)
> size = FTRACE_HASH_MAX_BITS;
> new_hash = alloc_ftrace_hash(size);
Yeah, this seems to make more sense. And I'll send a V2
later.
BTW, Should we still keep the "size = min(size, 32)" logic
to avoid the hash bits being too small, just like the origin
logic in "dup_hash"?
Thanks!
Menglong Dong
>
> -- Steve
>
>
