On Wed, 23 Apr 2014 18:58:30 +0200
Oleg Nesterov <o...@redhat.com> wrote:
> uprobe_perf_open()->uprobe_apply() can fail, but this error is wrongly
> ignored. Change uprobe_perf_open() to do uprobe_perf_close() and return
> the error code in this case.
>
> Change uprobe_perf_close() to propogate the error from uprobe_apply()
> as well, although it should not fail.
>
> The patch looks more complicated because it moves uprobe_perf_close()
> up to make it visible to uprobe_perf_open().
>
> Signed-off-by: Oleg Nesterov <o...@redhat.com>
> ---
> kernel/trace/trace_uprobe.c | 46 +++++++++++++++++++++++-------------------
> 1 files changed, 25 insertions(+), 21 deletions(-)
>
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index 930e514..9aad3e2 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -1003,56 +1003,60 @@ uprobe_filter_event(struct trace_uprobe *tu, struct
> perf_event *event)
> return __uprobe_perf_filter(&tu->filter, event->hw.tp_target->mm);
> }
>
> -static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event
> *event)
> +static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event
> *event)
Egad, this confused the heck out of me. I didn't notice the swap in
functions and was wondering what you were doing. I didn't realize this
is what you meant by moving the uprobe_perf_close() up. I was thinking
you moved the call up or something, not the function itself physically
in the file.
/me tries to continue dazed and confused.
> {
> bool done;
>
> write_lock(&tu->filter.rwlock);
> if (event->hw.tp_target) {
> - /*
> - * event->parent != NULL means copy_process(), we can avoid
> - * uprobe_apply(). current->mm must be probed and we can rely
> - * on dup_mmap() which preserves the already installed bp's.
> - *
> - * attr.enable_on_exec means that exec/mmap will install the
> - * breakpoints we need.
> - */
> + list_del(&event->hw.tp_list);
> done = tu->filter.nr_systemwide ||
> - event->parent || event->attr.enable_on_exec ||
> + (event->hw.tp_target->flags & PF_EXITING) ||
> uprobe_filter_event(tu, event);
> - list_add(&event->hw.tp_list, &tu->filter.perf_events);
> } else {
> + tu->filter.nr_systemwide--;
> done = tu->filter.nr_systemwide;
> - tu->filter.nr_systemwide++;
> }
> write_unlock(&tu->filter.rwlock);
>
> if (!done)
> - uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
> + return uprobe_apply(tu->inode, tu->offset, &tu->consumer,
> false);
>
> return 0;
> }
>
> -static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event
> *event)
> +static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event
> *event)
> {
> bool done;
> + int err;
>
> write_lock(&tu->filter.rwlock);
> if (event->hw.tp_target) {
> - list_del(&event->hw.tp_list);
> + /*
> + * event->parent != NULL means copy_process(), we can avoid
> + * uprobe_apply(). current->mm must be probed and we can rely
> + * on dup_mmap() which preserves the already installed bp's.
> + *
> + * attr.enable_on_exec means that exec/mmap will install the
> + * breakpoints we need.
> + */
> done = tu->filter.nr_systemwide ||
> - (event->hw.tp_target->flags & PF_EXITING) ||
> + event->parent || event->attr.enable_on_exec ||
> uprobe_filter_event(tu, event);
> + list_add(&event->hw.tp_list, &tu->filter.perf_events);
> } else {
> - tu->filter.nr_systemwide--;
> done = tu->filter.nr_systemwide;
> + tu->filter.nr_systemwide++;
> }
> write_unlock(&tu->filter.rwlock);
>
> - if (!done)
> - uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
> -
> - return 0;
> + err = 0;
> + if (!done) {
> + err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
> + if (err)
> + uprobe_perf_close(tu, event);
> + }
> + return err;
You can add by Acked-by, but next time, please make this into two
patches. One to do the move, the other to do the change.
Thanks!
-- Steve
> }
>
> static bool uprobe_perf_filter(struct uprobe_consumer *uc,
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
