Commit 59495740 authored by Florent Revest's avatar Florent Revest Committed by Steven Rostedt (Google)
Browse files

ftrace: Let unregister_ftrace_direct_multi() call ftrace_free_filter() 

A common pattern when using the ftrace_direct_multi API is to unregister
the ops and also immediately free its filter. We've noticed it's very
easy for users to miss calling ftrace_free_filter().

This adds a "free_filters" argument to unregister_ftrace_direct_multi()
to both remind the user they should free filters and also to make their
life easier.

Link: https://lkml.kernel.org/r/20230321140424.345218-2-revest@chromium.org



Suggested-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarFlorent Revest <revest@chromium.org>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent e8d018dd

include/linux/ftrace.h

+4 −2
Original line number Diff line number Diff line
@@ -407,7 +407,8 @@ int ftrace_modify_direct_caller(struct ftrace_func_entry *entry, 
				unsigned long new_addr);

unsigned long ftrace_find_rec_direct(unsigned long ip);

int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);

int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);

int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr,

				   bool free_filters);

int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);

int modify_ftrace_direct_multi_nolock(struct ftrace_ops *ops, unsigned long addr);
@@ -446,7 +447,8 @@ static inline int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned 
{

	return -ENODEV;

}

static inline int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)

static inline int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr,

						 bool free_filters)

{

	return -ENODEV;

}

kernel/bpf/trampoline.c

+1 −1
Original line number Diff line number Diff line
@@ -198,7 +198,7 @@ static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr) 
	int ret;



	if (tr->func.ftrace_managed)

		ret = unregister_ftrace_direct_multi(tr->fops, (long)old_addr);

		ret = unregister_ftrace_direct_multi(tr->fops, (long)old_addr, false);

	else

		ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, NULL);

kernel/trace/ftrace.c

+5 −1
Original line number Diff line number Diff line
@@ -5805,7 +5805,8 @@ EXPORT_SYMBOL_GPL(register_ftrace_direct_multi); 
 *  0 on success

 *  -EINVAL - The @ops object was not properly registered.

 */

int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)

int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr,

				   bool free_filters)

{

	struct ftrace_hash *hash = ops->func_hash->filter_hash;

	int err;
@@ -5823,6 +5824,9 @@ int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) 
	/* cleanup for possible another register call */

	ops->func = NULL;

	ops->trampoline = 0;



	if (free_filters)

		ftrace_free_filter(ops);

	return err;

}

EXPORT_SYMBOL_GPL(unregister_ftrace_direct_multi);

samples/ftrace/ftrace-direct-multi-modify.c

+1 −2
Original line number Diff line number Diff line
@@ -151,8 +151,7 @@ static int __init ftrace_direct_multi_init(void) 
static void __exit ftrace_direct_multi_exit(void)

{

	kthread_stop(simple_tsk);

	unregister_ftrace_direct_multi(&direct, my_tramp);

	ftrace_free_filter(&direct);

	unregister_ftrace_direct_multi(&direct, my_tramp, true);

}



module_init(ftrace_direct_multi_init);

samples/ftrace/ftrace-direct-multi.c

+1 −2
Original line number Diff line number Diff line
@@ -78,8 +78,7 @@ static int __init ftrace_direct_multi_init(void) 


static void __exit ftrace_direct_multi_exit(void)

{

	unregister_ftrace_direct_multi(&direct, (unsigned long) my_tramp);

	ftrace_free_filter(&direct);

	unregister_ftrace_direct_multi(&direct, (unsigned long) my_tramp, true);

}



module_init(ftrace_direct_multi_init);