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Date: Fri, 10 Jul 2020 15:22:31 +0100 From: Alan Maguire <alan.maguire@...cle.com> To: rostedt@...dmis.org, mingo@...hat.com, ast@...nel.org, daniel@...earbox.net, andriin@...com Cc: kafai@...com, songliubraving@...com, yhs@...com, john.fastabend@...il.com, kpsingh@...omium.org, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, bpf@...r.kernel.org, Alan Maguire <alan.maguire@...cle.com> Subject: [PATCH v2 bpf-next 0/2] bpf: fix use of trace_printk() in BPF Steven suggested a way to resolve the appearance of the warning banner that appears as a result of using trace_printk() in BPF [1]. Applying the patch and testing reveals all works as expected; we can call bpf_trace_printk() and see the trace messages in /sys/kernel/debug/tracing/trace_pipe and no banner message appears. Also add a test prog to verify basic bpf_trace_printk() helper behaviour. Changes since v1: - reorder header inclusion in bpf_trace.c (Steven, patch 1) - trace zero-length messages also (Andrii, patch 1) - use a raw spinlock to ensure there are no issues for PREMMPT_RT kernels when using bpf_trace_printk() within other raw spinlocks (Steven, patch 1) - always enable bpf_trace_printk() tracepoint when loading programs using bpf_trace_printk() as this will ensure that a user disabling that tracepoint will not prevent tracing output from being logged (Steven, patch 1) - use "tp/raw_syscalls/sys_enter" and a usleep(1) to trigger events in the selftest ensuring test runs faster (Andrii, patch 2) [1] https://lore.kernel.org/r/20200628194334.6238b933@oasis.local.home Alan Maguire (2): bpf: use dedicated bpf_trace_printk event instead of trace_printk() selftests/bpf: add selftests verifying bpf_trace_printk() behaviour kernel/trace/Makefile | 2 + kernel/trace/bpf_trace.c | 41 ++++++++++-- kernel/trace/bpf_trace.h | 34 ++++++++++ .../selftests/bpf/prog_tests/trace_printk.c | 74 ++++++++++++++++++++++ tools/testing/selftests/bpf/progs/trace_printk.c | 21 ++++++ 5 files changed, 167 insertions(+), 5 deletions(-) create mode 100644 kernel/trace/bpf_trace.h create mode 100644 tools/testing/selftests/bpf/prog_tests/trace_printk.c create mode 100644 tools/testing/selftests/bpf/progs/trace_printk.c -- 1.8.3.1
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