| Message ID | 20230316173811.1223508-2-revest@chromium.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Refactor ftrace direct call APIs | expand |
On Thu, Mar 16, 2023 at 06:38:05PM +0100, Florent Revest wrote: > 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. > > Suggested-by: Steven Rostedt <rostedt@goodmis.org> > Signed-off-by: Florent Revest <revest@chromium.org> > --- > include/linux/ftrace.h | 6 ++++-- > kernel/bpf/trampoline.c | 2 +- > kernel/trace/ftrace.c | 6 +++++- > samples/ftrace/ftrace-direct-multi-modify.c | 3 +-- > samples/ftrace/ftrace-direct-multi.c | 3 +-- > 5 files changed, 12 insertions(+), 8 deletions(-) This looks good to me; I see that the BPF code frees the filter in bpf_trampoline_put(), so it not doing so via unregister_ftrace_direct_multi() looks fine. FWIW: Acked-by: Mark Rutland <mark.rutland@arm.com> Mark. > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > index 366c730beaa3..5b68ee874bc1 100644 > --- a/include/linux/ftrace.h > +++ b/include/linux/ftrace.h > @@ -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; > } > diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c > index d0ed7d6f5eec..88bc23f1e10a 100644 > --- a/kernel/bpf/trampoline.c > +++ b/kernel/bpf/trampoline.c > @@ -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); > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 29baa97d0d53..fa379cf91fdb 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -5804,7 +5804,8 @@ 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; > @@ -5822,6 +5823,9 @@ 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); > diff --git a/samples/ftrace/ftrace-direct-multi-modify.c b/samples/ftrace/ftrace-direct-multi-modify.c > index b58c594efb51..196b43971cb5 100644 > --- a/samples/ftrace/ftrace-direct-multi-modify.c > +++ b/samples/ftrace/ftrace-direct-multi-modify.c > @@ -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); > diff --git a/samples/ftrace/ftrace-direct-multi.c b/samples/ftrace/ftrace-direct-multi.c > index c27cf130c319..ea0e88ee5e43 100644 > --- a/samples/ftrace/ftrace-direct-multi.c > +++ b/samples/ftrace/ftrace-direct-multi.c > @@ -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); > -- > 2.40.0.rc2.332.ga46443480c-goog >
On Tue, Mar 21, 2023 at 09:47:17AM +0000, Mark Rutland wrote: > On Thu, Mar 16, 2023 at 06:38:05PM +0100, Florent Revest wrote: > > 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. > > > > Suggested-by: Steven Rostedt <rostedt@goodmis.org> > > Signed-off-by: Florent Revest <revest@chromium.org> > > --- > > include/linux/ftrace.h | 6 ++++-- > > kernel/bpf/trampoline.c | 2 +- > > kernel/trace/ftrace.c | 6 +++++- > > samples/ftrace/ftrace-direct-multi-modify.c | 3 +-- > > samples/ftrace/ftrace-direct-multi.c | 3 +-- > > 5 files changed, 12 insertions(+), 8 deletions(-) > > This looks good to me; I see that the BPF code frees the filter in > bpf_trampoline_put(), so it not doing so via unregister_ftrace_direct_multi() > looks fine. FWIW: > > Acked-by: Mark Rutland <mark.rutland@arm.com> yes, I was going to ack the next version ;-) thanks, jirka > > Mark. > > > > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > > index 366c730beaa3..5b68ee874bc1 100644 > > --- a/include/linux/ftrace.h > > +++ b/include/linux/ftrace.h > > @@ -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; > > } > > diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c > > index d0ed7d6f5eec..88bc23f1e10a 100644 > > --- a/kernel/bpf/trampoline.c > > +++ b/kernel/bpf/trampoline.c > > @@ -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); > > > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > > index 29baa97d0d53..fa379cf91fdb 100644 > > --- a/kernel/trace/ftrace.c > > +++ b/kernel/trace/ftrace.c > > @@ -5804,7 +5804,8 @@ 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; > > @@ -5822,6 +5823,9 @@ 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); > > diff --git a/samples/ftrace/ftrace-direct-multi-modify.c b/samples/ftrace/ftrace-direct-multi-modify.c > > index b58c594efb51..196b43971cb5 100644 > > --- a/samples/ftrace/ftrace-direct-multi-modify.c > > +++ b/samples/ftrace/ftrace-direct-multi-modify.c > > @@ -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); > > diff --git a/samples/ftrace/ftrace-direct-multi.c b/samples/ftrace/ftrace-direct-multi.c > > index c27cf130c319..ea0e88ee5e43 100644 > > --- a/samples/ftrace/ftrace-direct-multi.c > > +++ b/samples/ftrace/ftrace-direct-multi.c > > @@ -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); > > -- > > 2.40.0.rc2.332.ga46443480c-goog > >
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 366c730beaa3..5b68ee874bc1 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -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; } diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index d0ed7d6f5eec..88bc23f1e10a 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -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); diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 29baa97d0d53..fa379cf91fdb 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -5804,7 +5804,8 @@ 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; @@ -5822,6 +5823,9 @@ 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); diff --git a/samples/ftrace/ftrace-direct-multi-modify.c b/samples/ftrace/ftrace-direct-multi-modify.c index b58c594efb51..196b43971cb5 100644 --- a/samples/ftrace/ftrace-direct-multi-modify.c +++ b/samples/ftrace/ftrace-direct-multi-modify.c @@ -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); diff --git a/samples/ftrace/ftrace-direct-multi.c b/samples/ftrace/ftrace-direct-multi.c index c27cf130c319..ea0e88ee5e43 100644 --- a/samples/ftrace/ftrace-direct-multi.c +++ b/samples/ftrace/ftrace-direct-multi.c @@ -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);
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. Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Florent Revest <revest@chromium.org> --- include/linux/ftrace.h | 6 ++++-- kernel/bpf/trampoline.c | 2 +- kernel/trace/ftrace.c | 6 +++++- samples/ftrace/ftrace-direct-multi-modify.c | 3 +-- samples/ftrace/ftrace-direct-multi.c | 3 +-- 5 files changed, 12 insertions(+), 8 deletions(-)