| Message ID | 20231207163458.5554-3-khuey@kylehuey.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | Combine perf and bpf for fast eval of hw breakpoint conditions | expand |
| Context | Check | Description |
|---|---|---|
| bpf/vmtest-bpf-next-PR | fail | PR summary |
| bpf/vmtest-bpf-next-VM_Test-1 | success | Logs for ShellCheck |
| bpf/vmtest-bpf-next-VM_Test-0 | success | Logs for Lint |
| bpf/vmtest-bpf-next-VM_Test-2 | success | Logs for Validate matrix.py |
| bpf/vmtest-bpf-next-VM_Test-3 | fail | Logs for aarch64-gcc / build / build for aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-4 | success | Logs for aarch64-gcc / test |
| bpf/vmtest-bpf-next-VM_Test-6 | fail | Logs for s390x-gcc / build / build for s390x with gcc |
| bpf/vmtest-bpf-next-VM_Test-5 | success | Logs for aarch64-gcc / veristat |
| bpf/vmtest-bpf-next-VM_Test-7 | success | Logs for s390x-gcc / test |
| bpf/vmtest-bpf-next-VM_Test-11 | success | Logs for x86_64-gcc / test |
| bpf/vmtest-bpf-next-VM_Test-10 | fail | Logs for x86_64-gcc / build / build for x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-9 | success | Logs for set-matrix |
| bpf/vmtest-bpf-next-VM_Test-12 | success | Logs for x86_64-gcc / veristat |
| bpf/vmtest-bpf-next-VM_Test-13 | fail | Logs for x86_64-llvm-16 / build / build for x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-8 | success | Logs for s390x-gcc / veristat |
| bpf/vmtest-bpf-next-VM_Test-14 | success | Logs for x86_64-llvm-16 / test |
| bpf/vmtest-bpf-next-VM_Test-15 | success | Logs for x86_64-llvm-16 / veristat |
On Thu, Dec 7, 2023 at 8:35 AM Kyle Huey <me@kylehuey.com> wrote: > > Returning zero from a bpf program attached to a perf event already > suppresses any data output. By clearing pending_kill, returning zero from a > bpf program will effectively pretend the sample never happened for all > userspace purposes. > > Signed-off-by: Kyle Huey <khuey@kylehuey.com> > --- > kernel/events/core.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > LGTM Acked-by: Andrii Nakryiko <andrii@kernel.org> > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 19fddfc27a4a..6cda05a4969d 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -10421,8 +10421,10 @@ static void bpf_overflow_handler(struct perf_event *event, > rcu_read_unlock(); > out: > __this_cpu_dec(bpf_prog_active); > - if (!ret) > + if (!ret) { > + event->pending_kill = 0; > return; > + } > > event->orig_overflow_handler(event, data, regs); > } > -- > 2.34.1 >
diff --git a/kernel/events/core.c b/kernel/events/core.c index 19fddfc27a4a..6cda05a4969d 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -10421,8 +10421,10 @@ static void bpf_overflow_handler(struct perf_event *event, rcu_read_unlock(); out: __this_cpu_dec(bpf_prog_active); - if (!ret) + if (!ret) { + event->pending_kill = 0; return; + } event->orig_overflow_handler(event, data, regs); }
Returning zero from a bpf program attached to a perf event already suppresses any data output. By clearing pending_kill, returning zero from a bpf program will effectively pretend the sample never happened for all userspace purposes. Signed-off-by: Kyle Huey <khuey@kylehuey.com> --- kernel/events/core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)