On Fri, Mar 18, 2022 at 02:42:49PM +0000, Geliang Tang wrote:

Hi Greg,

I got this bpf selftests build break today on the stable branch 5.10.106:

========================================================================= CLNG-LLC [test_maps] test_tracepoint.o progs/timer_crash.c:8:19: error: field has incomplete type 'struct bpf_timer' struct bpf_timer timer; ^ progs/timer_crash.c:8:9: note: forward declaration of 'struct bpf_timer' struct bpf_timer timer; ^ progs/timer_crash.c:35:6: warning: implicit declaration of function 'bpf_get_current_task_btf' is invalid in C99 [-Wimplicit-function-declaration] if (bpf_get_current_task_btf()->tgid != pid) ^ progs/timer_crash.c:35:34: error: member reference type 'int' is not a pointer if (bpf_get_current_task_btf()->tgid != pid) ~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ progs/timer_crash.c:49:3: warning: implicit declaration of function 'bpf_timer_cancel' is invalid in C99 [-Wimplicit-function-declaration] bpf_timer_cancel(&e->timer); ^ 2 warnings and 2 errors generated. CLNG-LLC [test_maps] test_trace_ext_tracing.o llc: error: llc: <stdin>:1:1: error: expected top-level entity BPF obj compilation failed ^ make: *** [Makefile:402: tools/testing/selftests/bpf/timer_crash.o] Error 1 make: *** Waiting for unfinished jobs.... CLNG-LLC [test_maps] test_trace_ext.o =========================================================================

It is introduced by this commit, "selftests/bpf: Add test for bpf_timer overwriting crash". Since the commit "bpf: Introduce bpf timers." has not been merged into the stable branch yet.

I am writing to you to report this bug.

Now reverted, thanks!

greg k-h