> On Nov 5, 2020, at 6:47 AM, KP Singh <kpsingh@xxxxxxxxxxxx> wrote:
>
> From: KP Singh <kpsingh@xxxxxxxxxx>
>
> Usage of spin locks was not allowed for tracing programs due to
> insufficient preemption checks. The verifier does not currently prevent
> LSM programs from using spin locks, but the helpers are not exposed
> via bpf_lsm_func_proto.
>
> Based on the discussion in [1], non-sleepable LSM programs should be
> able to use bpf_spin_{lock, unlock}.
>
> Sleepable LSM programs can be preempted which means that allowng spin
> locks will need more work (disabling preemption and the verifier
> ensuring that no sleepable helpers are called when a spin lock is held).
>
> [1]: https://lore.kernel.org/bpf/20201103153132.2717326-1-kpsingh@xxxxxxxxxxxx/T/#md601a053229287659071600d3483523f752cd2fb
>
> Signed-off-by: KP Singh <kpsingh@xxxxxxxxxx>
Acked-by: Song Liu <songliubraving@xxxxxx>
[...]
