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[209.132.180.67]) by mx.google.com with ESMTP id n127si47073152pfn.241.2016.09.08.05.45.45; Thu, 08 Sep 2016 05:45:45 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965307AbcIHMpm (ORCPT + 27 others); Thu, 8 Sep 2016 08:45:42 -0400 Received: from mail-pa0-f52.google.com ([209.85.220.52]:35098 "EHLO mail-pa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932478AbcIHMpl (ORCPT ); Thu, 8 Sep 2016 08:45:41 -0400 Received: by mail-pa0-f52.google.com with SMTP id b2so17225556pat.2 for ; Thu, 08 Sep 2016 05:45:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id; bh=VAupS1EwRHQqU4Uad6xD5LC4Zf3aEzNnGCuK0CodPvg=; b=itujJtqw4GBAnXa06wBixcFqBygYr/w0bbKmtHQUEFWM72XuUQPoIR7YrFPahedIvZ 9xAadcZ+TpiAjIDgfFx4V9y0qEVrixwEeyd6oQsGTkQkp0rpzqI5qXON+Ayj4eH3gJKm MhIdIkqbx/pM7rMy5PmLE0KDBeKvswqUJ8X/8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=VAupS1EwRHQqU4Uad6xD5LC4Zf3aEzNnGCuK0CodPvg=; b=eFiCieTiK66VUMfOKp3W6DP2mCo+Thji6gUoRg+eUvBoM60y7TmCNUUchsbN4LTtdn 3QMGKCK1k+Ykqk72yUhcF95O6ud+PN4QG/XZZhEsuAwg/w56npwwg5G36L/FBZgmoyDU 2JMp0DNz6rXbXRY4kGTgjpBmNq0iJMk+p/IoUzXARzHL59t04BUdLQBkIg8efI0e9NLd NNZtpN9OzcGA00DzG1LIOx/E/35jrfNZUq0DeCURaAS1yoAPCZBdO0F75eJ2xI41wsq+ e/Ak+kfe+feAVB/6emdYZHpcg9ojlhqoK73yfVB/NI9PiUUD3eh8/ItV9y0tRjLfscea d/Sg== X-Gm-Message-State: AE9vXwPeGRu3Uo6JWJwoVt69ufAk1lq7wJoh14hFnOnBfN0AU7mUQTz9GigeDV4rbYJ6ajxD X-Received: by 10.66.88.135 with SMTP id bg7mr20182391pab.107.1473338740172; Thu, 08 Sep 2016 05:45:40 -0700 (PDT) Received: from ubuntu16.spreadtrum.com ([175.111.195.49]) by smtp.gmail.com with ESMTPSA id w81sm21776629pfa.54.2016.09.08.05.45.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 08 Sep 2016 05:45:39 -0700 (PDT) From: Chunyan Zhang To: rostedt@goodmis.org, mingo@redhat.com Cc: zhang.lyra@gmail.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.orgi, takahiro.akashi@linaro.org, mark.yang@spreadtrum.com Subject: [PATCH] arm64: use preempt_disable_notrace in _percpu_read/write Date: Thu, 8 Sep 2016 20:45:19 +0800 Message-Id: <1473338719-18647-1-git-send-email-zhang.chunyan@linaro.org> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When debug preempt or preempt tracer is enabled, preempt_count_add/sub() can be traced by function and function graph tracing, and preempt_disable/enable() would call preempt_count_add/sub(), so in Ftrace subsystem we should use preempt_disable/enable_notrace instead. In the commit 345ddcc882d8 ("ftrace: Have set_ftrace_pid use the bitmap like events do") the function this_cpu_read() was added to trace_graph_entry(), and if this_cpu_read() calls preempt_disable(), graph tracer will go into a recursive loop, even if the tracing_on is disabled. So this patch change to use preempt_enable/disable_notrace instead in this_cpu_read(). Since Yonghui Yang helped a lot to find the root cause of this problem, so also add his SOB. Signed-off-by: Yonghui Yang Signed-off-by: Chunyan Zhang --- arch/arm64/include/asm/percpu.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) -- 2.7.4 diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h index 0a456be..2fee2f5 100644 --- a/arch/arm64/include/asm/percpu.h +++ b/arch/arm64/include/asm/percpu.h @@ -199,19 +199,19 @@ static inline unsigned long __percpu_xchg(void *ptr, unsigned long val, #define _percpu_read(pcp) \ ({ \ typeof(pcp) __retval; \ - preempt_disable(); \ + preempt_disable_notrace(); \ __retval = (typeof(pcp))__percpu_read(raw_cpu_ptr(&(pcp)), \ sizeof(pcp)); \ - preempt_enable(); \ + preempt_enable_notrace(); \ __retval; \ }) #define _percpu_write(pcp, val) \ do { \ - preempt_disable(); \ + preempt_disable_notrace(); \ __percpu_write(raw_cpu_ptr(&(pcp)), (unsigned long)(val), \ sizeof(pcp)); \ - preempt_enable(); \ + preempt_enable_notrace(); \ } while(0) \ #define _pcp_protect(operation, pcp, val) \