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
CONFIG_SMP set or not.
Fixes:
fe147956fca4 ("bpf/selftests: Add selftests for new task kfuncs")
Fixes:
48671232fcb8 ("selftests/bpf: Add tests for bpf_rcu_read_lock()")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20221213012224.379581-1-yhs@fb.com
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;
}
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);
bpf_task_release(acquired);
return 0;