Re: [RFC PATCH v2 04/14] kcov: reject enable on multiple dataflow fds simultaneously

Alexander Potapenko <[email protected]> Fri, 12 Jun 2026 09:32:43 +0200

Newsgroups	org.kernel.vger.workflows,dev.linux.lists.llvm,org.kernel.vger.linux-doc,org.kernel.vger.linux-kbuild,org.kernel.vger.linux-kernel,org.kernel.vger.linux-kselftest,org.kernel.vger.rust-for-linux,org.kvack.linux-mm
Message-ID	<CAG_fn=UJTVm+XVjq-wq1GsfFLvQuET7N1A6ZF_BWtYwmDab_TQ@mail.gmail.com>

On Thu, Jun 11, 2026 at 6:21 PM Yunseong Kim <[email protected]> wrote:
>
> A task could enable tracing on multiple kcov_dataflow file descriptors,
> corrupting the internal tracking state when one is subsequently closed.
>
> Check current->kcov_df_enabled before allowing KCOV_DF_ENABLE and
> return -EBUSY if already active. This matches kcov's check of
> t->kcov != NULL in the KCOV_ENABLE path.
>
> Reported-by: sashiko-bot <[email protected]>
> Closes: https://sashiko.dev/#/patchset/20260603-kcov-dataflow-next-20260603-v2-0-fee0939de2c4%40est.tech
> Signed-off-by: Yunseong Kim <[email protected]>
> ---
>  kernel/kcov_dataflow.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/kcov_dataflow.c b/kernel/kcov_dataflow.c
> index 5248293280d5..27587b8ceeab 100644
> --- a/kernel/kcov_dataflow.c
> +++ b/kernel/kcov_dataflow.c

Please merge this patch into the one introducing kcov_dataflow.c