On Mon, Dec 12, 2022 at 03:46:17PM -0800, Yonghong Song wrote:
> Kernel test robot reported bpf selftest build failure when CONFIG_SMP
> is not set. The error message looks below:
>
> >> progs/rcu_read_lock.c:256:34: error: no member named 'last_wakee' in 'struct task_struct'
> last_wakee = task->real_parent->last_wakee;
> ~~~~~~~~~~~~~~~~~ ^
> 1 error generated.
>
> When CONFIG_SMP is not set, the field 'last_wakee' is not available in struct
> 'task_struct'. Hence the above compilation failure. To fix the issue, let us
> choose another field 'group_leader' which is available regardless of
> CONDFIG_SMP set or not.
s/CONDFIG_SMP/CONFIG_SMP
>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
> tools/testing/selftests/bpf/progs/rcu_read_lock.c | 8 ++++----
> tools/testing/selftests/bpf/progs/task_kfunc_failure.c | 2 +-
> 2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/progs/rcu_read_lock.c b/tools/testing/selftests/bpf/progs/rcu_read_lock.c
> index 125f908024d3..5cecbdbbb16e 100644
> --- a/tools/testing/selftests/bpf/progs/rcu_read_lock.c
> +++ b/tools/testing/selftests/bpf/progs/rcu_read_lock.c
> @@ -288,13 +288,13 @@ int nested_rcu_region(void *ctx)
> SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
> int task_untrusted_non_rcuptr(void *ctx)
> {
> - struct task_struct *task, *last_wakee;
> + struct task_struct *task, *group_leader;
>
> task = bpf_get_current_task_btf();
> bpf_rcu_read_lock();
> - /* the pointer last_wakee marked as untrusted */
> - last_wakee = task->real_parent->last_wakee;
> - (void)bpf_task_storage_get(&map_a, last_wakee, 0, 0);
> + /* the pointer group_leader marked as untrusted */
> + group_leader = task->real_parent->group_leader;
> + (void)bpf_task_storage_get(&map_a, group_leader, 0, 0);
> bpf_rcu_read_unlock();
> return 0;
> }
> diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_failure.c b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c
> index 87fa1db9d9b5..1b47b94dbca0 100644
> --- a/tools/testing/selftests/bpf/progs/task_kfunc_failure.c
> +++ b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c
> @@ -73,7 +73,7 @@ int BPF_PROG(task_kfunc_acquire_trusted_walked, struct task_struct *task, u64 cl
> struct task_struct *acquired;
>
> /* Can't invoke bpf_task_acquire() on a trusted pointer obtained from walking a struct. */
> - acquired = bpf_task_acquire(task->last_wakee);
> + acquired = bpf_task_acquire(task->group_leader);
Ah, I missed that you'd sent this out before I sent out [0]. Thanks for
fixing this for me. I'm fine with just merging this patch and dropping
[0] if it's easier for the maintainers.
[0]: https://lore.kernel.org/all/20221212235344.1563280-1-void@xxxxxxxxxxxxx/
> bpf_task_release(acquired);
>
> return 0;
> --
> 2.30.2
>
