From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 74AC084D60; Mon, 18 Dec 2023 12:47:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rYKmmq+B" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79B1CC433C7; Mon, 18 Dec 2023 12:47:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702903628; bh=Uo2fuLQMvbyweP2Ic7zZnU2gascwCIq18ozIbLJ8O30=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rYKmmq+BFS8HpgDF8PxD+Kgaq6uQIKlB9u6dhwXTFRaJe+r5xw/NGLqH3Q//7ZSwx /GRlE8EtGE7gnI0LohCspkgAD9qRvENE6szYQ9zrF6+yMSwZMLx9pU1gKudZD81uwF rcpba+HSnH9OnidxXzePJf511wenOLw/91cHmti0Y1LcCt5E0shcDq9ZLrU0tVtD2t 5Ypy8tyJdckTUbtQuSR8Q2b+EEBfVF/1xuhllSjLyfmhhd/1v6M7xX14W+HWm2hcI2 Wv9oj1DUe897ko527cyGHSd6AeEIzOKKCvHYqHYs+mRoOiuDiGVVb199GudYJ8mJ/O mCFryEJbL3DoQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Steven Rostedt (Google)" , Mark Rutland , Mathieu Desnoyers , Masami Hiramatsu , Sasha Levin , linux-trace-kernel@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 5/7] tracing: Have large events show up as '[LINE TOO BIG]' instead of nothing Date: Mon, 18 Dec 2023 07:46:50 -0500 Message-ID: <20231218124656.1381949-5-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231218124656.1381949-1-sashal@kernel.org> References: <20231218124656.1381949-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.4.264 Content-Transfer-Encoding: 8bit From: "Steven Rostedt (Google)" [ Upstream commit b55b0a0d7c4aa2dac3579aa7e6802d1f57445096 ] If a large event was added to the ring buffer that is larger than what the trace_seq can handle, it just drops the output: ~# cat /sys/kernel/tracing/trace # tracer: nop # # entries-in-buffer/entries-written: 2/2 #P:8 # # _-----=> irqs-off/BH-disabled # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / _-=> migrate-disable # |||| / delay # TASK-PID CPU# ||||| TIMESTAMP FUNCTION # | | | ||||| | | <...>-859 [001] ..... 141.118951: tracing_mark_write <...>-859 [001] ..... 141.148201: tracing_mark_write: 78901234 Instead, catch this case and add some context: ~# cat /sys/kernel/tracing/trace # tracer: nop # # entries-in-buffer/entries-written: 2/2 #P:8 # # _-----=> irqs-off/BH-disabled # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / _-=> migrate-disable # |||| / delay # TASK-PID CPU# ||||| TIMESTAMP FUNCTION # | | | ||||| | | <...>-852 [001] ..... 121.550551: tracing_mark_write[LINE TOO BIG] <...>-852 [001] ..... 121.550581: tracing_mark_write: 78901234 This now emulates the same output as trace_pipe. Link: https://lore.kernel.org/linux-trace-kernel/20231209171058.78c1a026@gandalf.local.home Cc: Mark Rutland Cc: Mathieu Desnoyers Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin --- kernel/trace/trace.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d7ca8f97b315f..35c1500855566 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4078,7 +4078,11 @@ static int s_show(struct seq_file *m, void *v) iter->leftover = ret; } else { - print_trace_line(iter); + ret = print_trace_line(iter); + if (ret == TRACE_TYPE_PARTIAL_LINE) { + iter->seq.full = 0; + trace_seq_puts(&iter->seq, "[LINE TOO BIG]\n"); + } ret = trace_print_seq(m, &iter->seq); /* * If we overflow the seq_file buffer, then it will -- 2.43.0