2023-07-03 07:23:11

by Ze Gao

Subject: [PATCH] fprobe: add unlock to match a succeeded ftrace_test_recursion_trylock

Fixes: 3cc4e2c5fbae ("fprobe: make fprobe_kprobe_handler recursion free")
Reported-by: Yafang <[email protected]>
Closes: https://lore.kernel.org/linux-trace-kernel/CALOAHbC6UpfFOOibdDiC7xFc5YFUgZnk3MZ=3Ny6we=AcrNbew@mail.gmail.com/
Signed-off-by: Ze Gao <[email protected]>
---
kernel/trace/fprobe.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index 18d36842faf5..93b3e361bb97 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -102,12 +102,14 @@ static void fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip,

if (unlikely(kprobe_running())) {
fp->nmissed++;
- return;
+ goto recursion_unlock;
}

kprobe_busy_begin();
__fprobe_handler(ip, parent_ip, ops, fregs);
kprobe_busy_end();
+
+recursion_unlock:
ftrace_test_recursion_unlock(bit);
}

--
2.40.1

2023-07-03 08:33:19

by Masami Hiramatsu

Subject: Re: [PATCH] fprobe: add unlock to match a succeeded ftrace_test_recursion_trylock

On Mon, 3 Jul 2023 15:16:40 +0800
Ze Gao <[email protected]> wrote:

Good catch! but please add description here, something like;

----
Unlock ftrace recursion lock when fprobe_kprobe_handler() is failed
because another kprobe is running.
----

The code itself is OK to me.


> Fixes: 3cc4e2c5fbae ("fprobe: make fprobe_kprobe_handler recursion free")
> Reported-by: Yafang <[email protected]>
> Closes: https://lore.kernel.org/linux-trace-kernel/CALOAHbC6UpfFOOibdDiC7xFc5YFUgZnk3MZ=3Ny6we=AcrNbew@mail.gmail.com/
> Signed-off-by: Ze Gao <[email protected]>
> ---
> kernel/trace/fprobe.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
> index 18d36842faf5..93b3e361bb97 100644
> --- a/kernel/trace/fprobe.c
> +++ b/kernel/trace/fprobe.c
> @@ -102,12 +102,14 @@ static void fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip,
>
> if (unlikely(kprobe_running())) {
> fp->nmissed++;
> - return;
> + goto recursion_unlock;
> }
>
> kprobe_busy_begin();
> __fprobe_handler(ip, parent_ip, ops, fregs);
> kprobe_busy_end();
> +
> +recursion_unlock:
> ftrace_test_recursion_unlock(bit);
> }
>
> --
> 2.40.1
>


--
Masami Hiramatsu (Google) <[email protected]>

2023-07-03 09:37:35

by Ze Gao

Subject: Re: [PATCH] fprobe: add unlock to match a succeeded ftrace_test_recursion_trylock

Good suggestion! Will amend and push v2 ASAP.

Thanks,
Ze

On Mon, Jul 3, 2023 at 4:19 PM Masami Hiramatsu <[email protected]> wrote:
>
> On Mon, 3 Jul 2023 15:16:40 +0800
> Ze Gao <[email protected]> wrote:
>
> Good catch! but please add description here, something like;
>
> ----
> Unlock ftrace recursion lock when fprobe_kprobe_handler() is failed
> because another kprobe is running.
> ----
>
> The code itself is OK to me.
>
>
> > Fixes: 3cc4e2c5fbae ("fprobe: make fprobe_kprobe_handler recursion free")
> > Reported-by: Yafang <[email protected]>
> > Closes: https://lore.kernel.org/linux-trace-kernel/CALOAHbC6UpfFOOibdDiC7xFc5YFUgZnk3MZ=3Ny6we=AcrNbew@mail.gmail.com/
> > Signed-off-by: Ze Gao <[email protected]>
> > ---
> > kernel/trace/fprobe.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
> > index 18d36842faf5..93b3e361bb97 100644
> > --- a/kernel/trace/fprobe.c
> > +++ b/kernel/trace/fprobe.c
> > @@ -102,12 +102,14 @@ static void fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip,
> >
> > if (unlikely(kprobe_running())) {
> > fp->nmissed++;
> > - return;
> > + goto recursion_unlock;
> > }
> >
> > kprobe_busy_begin();
> > __fprobe_handler(ip, parent_ip, ops, fregs);
> > kprobe_busy_end();
> > +
> > +recursion_unlock:
> > ftrace_test_recursion_unlock(bit);
> > }
> >
> > --
> > 2.40.1
> >
>
>
> --
> Masami Hiramatsu (Google) <[email protected]>