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ftrace: Let unregister_ftrace_direct_multi() call ftrace_free_filter()

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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: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Florent Revest <revest@chromium.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Florent Revest 2023-03-21 15:04:18 +01:00 committed by Steven Rostedt (Google)
parent e8d018dd02
commit 59495740f7
5 changed files with 12 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/ftrace.h
View File

@ -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;
}

2
kernel/bpf/trampoline.c
View File

@ -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);

6
kernel/trace/ftrace.c
View File

@ -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);

3
samples/ftrace/ftrace-direct-multi-modify.c
View File

@ -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);

3
samples/ftrace/ftrace-direct-multi.c
View File

@ -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);