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[213.113.33.115]) by smtp.gmail.com with ESMTPSA id m13-v6sm858237ljg.56.2018.11.30.07.09.40 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 30 Nov 2018 07:09:40 -0800 (PST) From: Anders Roxell To: rostedt@goodmis.org, mingo@redhat.com Cc: keescook@chromium.org, catalin.marinas@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Anders Roxell , Arnd Bergmann Subject: [PATCH 2/3] tracing: instruct KCOV not to track tracing files Date: Fri, 30 Nov 2018 16:09:35 +0100 Message-Id: <20181130150935.27493-1-anders.roxell@linaro.org> X-Mailer: git-send-email 2.19.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When we have KCOV enabled and running ftrace startup tests we end up in a softlockup. Kcov and ftrace tracing each other makes it really slow: [ 275.141388] Testing tracer wakeup_dl: PASSED [ 304.738345] Testing tracer function_graph: [ 716.236822] watchdog: BUG: soft lockup - CPU#0 stuck for 21s! [ksoftirqd/0:9] Rework so that we don't let KCOV look at tracing files. Could probably be more selective here, but in in general letting KCOV and ftrace check each isn't the best idea. Co-developed-by: Arnd Bergmann Signed-off-by: Arnd Bergmann Signed-off-by: Anders Roxell --- kernel/trace/Makefile | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index f81dadbc7c4a..c7c73b976103 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -6,6 +6,11 @@ ifdef CONFIG_FUNCTION_TRACER ORIG_CFLAGS := $(KBUILD_CFLAGS) KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS)) +# If instrumentation of this dir is enabled, the function tracer gets really +# slow. Probably could be more selective here, but note that files related +# to tracing.shouldn't be traced anyway. +KCOV_INSTRUMENT := n + ifdef CONFIG_FTRACE_SELFTEST # selftest needs instrumentation CFLAGS_trace_selftest_dynamic.o = $(CC_FLAGS_FTRACE) -- 2.19.2