Re: [RFC PATCH 2/2] lib, stackdepot: Add helper to print stack entries.

[imran . f . khan]

Hi Vlastimil,

On 1/9/21 7:07 pm, Vlastimil Babka wrote:
> On 9/1/21 07:19, Imran Khan wrote:
> > To print a stack entries, users of stackdepot, first
> > use stack_depot_fetch to get a list of stack entries
> > and then use stack_trace_print to print this list.
> > Provide a helper in stackdepot to print stack entries
> > based on stackdepot handle.
> >
> > Signed-off-by: Imran Khan <imran.f.khan@xxxxxxxxxx>
> > Suggested-by: Vlastimil Babka <vbabka@xxxxxxx>
>
> You should convert existing users together with the patch that introduces
> the helper. I think print_stack() in mm/kasan/report.c, and
> __dump_page_owner() could use this.

Okay. I have done this in v2 of the patch set. BTW I also see some users 
(one place in page owner, rest all in some gpu drivers) of 
stack_depot_fetch + stack_trace_snprintf. Could you please let me know 
if it would be okay to add a helper corresponding to 
stack_trace_snprintf as well.

> > ---
> >   lib/stackdepot.c | 17 +++++++++++++++++
> >   1 file changed, 17 insertions(+)
>
> It's missing a declaration in include/linux/stackdepot.h
> Perhaps it could be all be a static inline there anyway.

Agree. I have added missing declaration now. I have not made it inline
though.
> > diff --git a/lib/stackdepot.c b/lib/stackdepot.c
> > index 1d42ef9ef766..eab4476b060b 100644
> > --- a/lib/stackdepot.c
> > +++ b/lib/stackdepot.c
> > @@ -214,6 +214,23 @@ static inline struct stack_record *find_stack(struct stack_record *bucket,
> >   	return NULL;
> >   }
> >   
> > +/**
> > + * stack_depot_print - print stack entries from a depot
> > + *
> > + * @handle:		Stack depot handle which was returned from
> > + *			stack_depot_save().
> > + *
> > + */
> > +void stack_depot_print(depot_stack_handle_t stack)
> > +{
> > +	unsigned long *entries;
> > +	unsigned int nr_entries;
> > +
> > +	nr_entries = stack_depot_fetch(stack, &entries);
> > +	stack_trace_print(entries, nr_entries, 0);
> > +}
> > +EXPORT_SYMBOL_GPL(stack_depot_print);
> > +
> >   /**
> >    * stack_depot_fetch - Fetch stack entries from a depot
> >    *

Thanks again for the review.

--Imran