@@ -1888,10 +1888,8 @@ 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, bool cleanup_hprobe)
+static void free_ret_instance(struct return_instance *ri, bool cleanup_hprobe)
{
- struct return_instance *next = ri->next;
-
if (cleanup_hprobe) {
enum hprobe_state hstate;
@@ -1901,7 +1899,6 @@ static struct return_instance *free_ret_instance(struct return_instance *ri, boo
kfree(ri->extra_consumers);
kfree_rcu(ri, rcu);
- return next;
}
/*
@@ -1911,7 +1908,7 @@ static struct return_instance *free_ret_instance(struct return_instance *ri, boo
void uprobe_free_utask(struct task_struct *t)
{
struct uprobe_task *utask = t->utask;
- struct return_instance *ri;
+ struct return_instance *ri, *ri_next;
if (!utask)
return;
@@ -1921,8 +1918,11 @@ void uprobe_free_utask(struct task_struct *t)
timer_delete_sync(&utask->ri_timer);
ri = utask->return_instances;
- while (ri)
- ri = free_ret_instance(ri, true /* cleanup_hprobe */);
+ while (ri) {
+ ri_next = ri->next;
+ free_ret_instance(ri, true /* cleanup_hprobe */);
+ ri = ri_next;
+ }
kfree(utask);
t->utask = NULL;
@@ -2111,12 +2111,15 @@ unsigned long uprobe_get_trampoline_vaddr(void)
static void cleanup_return_instances(struct uprobe_task *utask, bool chained,
struct pt_regs *regs)
{
- struct return_instance *ri = utask->return_instances;
+ struct return_instance *ri = utask->return_instances, *ri_next;
enum rp_check ctx = chained ? RP_CHECK_CHAIN_CALL : RP_CHECK_CALL;
while (ri && !arch_uretprobe_is_alive(ri, ctx, regs)) {
- ri = free_ret_instance(ri, true /* cleanup_hprobe */);
+ ri_next = ri->next;
utask->depth--;
+
+ free_ret_instance(ri, true /* cleanup_hprobe */);
+ ri = ri_next;
}
rcu_assign_pointer(utask->return_instances, ri);
}
@@ -2508,7 +2511,7 @@ static struct return_instance *find_next_ret_chain(struct return_instance *ri)
void uprobe_handle_trampoline(struct pt_regs *regs)
{
struct uprobe_task *utask;
- struct return_instance *ri, *next;
+ struct return_instance *ri, *ri_next, *next_chain;
struct uprobe *uprobe;
enum hprobe_state hstate;
bool valid;
@@ -2528,8 +2531,8 @@ void uprobe_handle_trampoline(struct pt_regs *regs)
* or NULL; the latter case means that nobody but ri->func
* could hit this trampoline on return. TODO: sigaltstack().
*/
- next = find_next_ret_chain(ri);
- valid = !next || arch_uretprobe_is_alive(next, RP_CHECK_RET, regs);
+ next_chain = find_next_ret_chain(ri);
+ valid = !next_chain || arch_uretprobe_is_alive(next_chain, RP_CHECK_RET, regs);
instruction_pointer_set(regs, ri->orig_ret_vaddr);
do {
@@ -2541,7 +2544,9 @@ void uprobe_handle_trampoline(struct pt_regs *regs)
* trampoline addresses on the stack are replaced with correct
* original return addresses
*/
- rcu_assign_pointer(utask->return_instances, ri->next);
+ ri_next = ri->next;
+ rcu_assign_pointer(utask->return_instances, ri_next);
+ utask->depth--;
uprobe = hprobe_consume(&ri->hprobe, &hstate);
if (valid)
@@ -2549,9 +2554,9 @@ void uprobe_handle_trampoline(struct pt_regs *regs)
hprobe_finalize(&ri->hprobe, hstate);
/* We already took care of hprobe, no need to waste more time on that. */
- ri = free_ret_instance(ri, false /* !cleanup_hprobe */);
- utask->depth--;
- } while (ri != next);
+ free_ret_instance(ri, false /* !cleanup_hprobe */);
+ ri = ri_next;
+ } while (ri != next_chain);
} while (!valid);
return;
free_ret_instance() has two unrelated responsibilities: actually cleaning up return_instance's resources and freeing memory, and also helping with utask->return_instances list traversal by returning the next alive pointer. There is no reason why these two aspects have to be mixed together, so turn free_ret_instance() into void-returning function and make callers do list traversal on their own. We'll use this simplification in the next patch that will guarantee that to-be-freed return_instance isn't reachable from utask->return_instances list. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> --- kernel/events/uprobes.c | 37 +++++++++++++++++++++---------------- 1 file changed, 21 insertions(+), 16 deletions(-)