On Tue, Jul 07, 2015 at 03:22:39AM +0200, Oleg Nesterov wrote:
> We can simplify uprobe_free_utask() and handle_uretprobe_chain()
> if we add a simple helper which does put_uprobe/kfree and returns
> the ->next return_instance.
>
> Signed-off-by: Oleg Nesterov <o...@redhat.com>
> Acked-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
Acked-by: Anton Arapov <ara...@gmail.com>
> ---
> kernel/events/uprobes.c | 27 +++++++++++++--------------
> 1 files changed, 13 insertions(+), 14 deletions(-)
>
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index a9847b4..d8c702f 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1378,6 +1378,14 @@ unsigned long uprobe_get_trap_addr(struct pt_regs
> *regs)
> return instruction_pointer(regs);
> }
>
> +static struct return_instance *free_ret_instance(struct return_instance *ri)
> +{
> + struct return_instance *next = ri->next;
> + put_uprobe(ri->uprobe);
> + kfree(ri);
> + return next;
> +}
> +
> /*
> * Called with no locks held.
> * Called in context of a exiting or a exec-ing thread.
> @@ -1385,7 +1393,7 @@ unsigned long uprobe_get_trap_addr(struct pt_regs *regs)
> void uprobe_free_utask(struct task_struct *t)
> {
> struct uprobe_task *utask = t->utask;
> - struct return_instance *ri, *tmp;
> + struct return_instance *ri;
>
> if (!utask)
> return;
> @@ -1394,13 +1402,8 @@ void uprobe_free_utask(struct task_struct *t)
> put_uprobe(utask->active_uprobe);
>
> ri = utask->return_instances;
> - while (ri) {
> - tmp = ri;
> - ri = ri->next;
> -
> - put_uprobe(tmp->uprobe);
> - kfree(tmp);
> - }
> + while (ri)
> + ri = free_ret_instance(ri);
>
> xol_free_insn_slot(t);
> kfree(utask);
> @@ -1770,7 +1773,7 @@ handle_uretprobe_chain(struct return_instance *ri,
> struct pt_regs *regs)
> static bool handle_trampoline(struct pt_regs *regs)
> {
> struct uprobe_task *utask;
> - struct return_instance *ri, *tmp;
> + struct return_instance *ri;
> bool chained;
>
> utask = current->utask;
> @@ -1792,11 +1795,7 @@ static bool handle_trampoline(struct pt_regs *regs)
> handle_uretprobe_chain(ri, regs);
>
> chained = ri->chained;
> - put_uprobe(ri->uprobe);
> -
> - tmp = ri;
> - ri = ri->next;
> - kfree(tmp);
> + ri = free_ret_instance(ri);
> utask->depth--;
>
> if (!chained)
> --
> 1.5.5.1
>
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