On Mon, 12 Feb 2024 15:39:03 -0800
Tim Chen <tim.c.c...@linux.intel.com> wrote:
> > diff --git a/kernel/trace/trace_sched_switch.c
> > b/kernel/trace/trace_sched_switch.c
> > index e4fbcc3bede5..210c74dcd016 100644
> > --- a/kernel/trace/trace_sched_switch.c
> > +++ b/kernel/trace/trace_sched_switch.c
> > @@ -201,7 +201,7 @@ static struct saved_cmdlines_buffer
> > *allocate_cmdlines_buffer(unsigned int val)
> > int order;
> >
> > /* Figure out how much is needed to hold the given number of cmdlines */
> > - orig_size = sizeof(*s) + val * TASK_COMM_LEN;
> > + orig_size = sizeof(*s) + val * (TASK_COMM_LEN + sizeof(int));
>
> Strictly speaking, *map_cmdline_to_pid is unsigned int so it is more
> consistent
> to use sizeof(unsigned) in line above. But I'm nitpicking and I'm fine to
> leave it as is.
I was thinking about making that into a macro as it is used in two places.
/* Holds the size of a cmdline and pid element */
#define SAVED_CMDLINE_MAP_ELEMENT_SIZE(s) \
(TASK_COMM_LEN + sizeof((s)->map_cmdline_to_pid[0]))
orig_size = sizeof(*s) + val * SAVED_CMDLINE_MAP_ELEMENT_SIZE(s);
>
> > order = get_order(orig_size);
> > size = 1 << (order + PAGE_SHIFT);
> > page = alloc_pages(GFP_KERNEL, order);
> > @@ -212,16 +212,11 @@ static struct saved_cmdlines_buffer
> > *allocate_cmdlines_buffer(unsigned int val)
> > memset(s, 0, sizeof(*s));
> >
> > /* Round up to actual allocation */
> > - val = (size - sizeof(*s)) / TASK_COMM_LEN;
> > + val = (size - sizeof(*s)) / (TASK_COMM_LEN + sizeof(int));
val = (size - sizeof(*s)) / SAVED_CMDLINE_MAP_ELEMENT_SIZE(s);
-- Steve
> > s->cmdline_num = val;
> >
> > - s->map_cmdline_to_pid = kmalloc_array(val,
> > - sizeof(*s->map_cmdline_to_pid),
> > - GFP_KERNEL);
> > - if (!s->map_cmdline_to_pid) {
> > - free_saved_cmdlines_buffer(s);
> > - return NULL;
> > - }
> > + /* Place map_cmdline_to_pid array right after saved_cmdlines */
> > + s->map_cmdline_to_pid = (unsigned *)&s->saved_cmdlines[val *
> > TASK_COMM_LEN];
> >
> > s->cmdline_idx = 0;
> > memset(&s->map_pid_to_cmdline, NO_CMDLINE_MAP,
