[PATCH 02/10] uprobes: Introduce free_ret_instance()

From: Oleg Nesterov
Date: Mon May 04 2015 - 08:50:21 EST


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 <oleg@xxxxxxxxxx>
---
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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