From patchwork Sat Dec 9 22:52:20 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13486127 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 44AEC1EA7E for ; Sat, 9 Dec 2023 22:51:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0731FC433C9; Sat, 9 Dec 2023 22:51:44 +0000 (UTC) Date: Sat, 9 Dec 2023 17:52:20 -0500 From: Steven Rostedt To: LKML , Linux Trace Kernel Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers Subject: [PATCH] trace_seq: Increase the buffer size to almost two pages Message-ID: <20231209175220.19867af4@gandalf.local.home> X-Mailer: Claws Mail 3.19.1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: "Steven Rostedt (Google)" Now that trace_marker can hold more than 1KB string, and can write as much as the ring buffer can hold, the trace_seq is not big enough to hold writes: ~# a="1234567890" ~# cnt=4080 ~# s="" ~# while [ $cnt -gt 10 ]; do ~# s="${s}${a}" ~# cnt=$((cnt-10)) ~# done ~# echo $s > trace_marker ~# cat 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 # | | | ||||| | | <...>-860 [002] ..... 105.543465: tracing_mark_write[LINE TOO BIG] <...>-860 [002] ..... 105.543496: tracing_mark_write: 789012345678901234567890 By increasing the trace_seq buffer to almost two pages, it can now print out the first line. This also subtracts the rest of the trace_seq fields from the buffer, so that the entire trace_seq is now PAGE_SIZE aligned. Signed-off-by: Steven Rostedt (Google) Reviewed-by: Masami Hiramatsu (Google) --- include/linux/trace_seq.h | 9 ++++++--- kernel/trace/trace.c | 6 +++--- kernel/trace/trace_seq.c | 3 --- 3 files changed, 9 insertions(+), 9 deletions(-) diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h index 3691e0e76a1a..9ec229dfddaa 100644 --- a/include/linux/trace_seq.h +++ b/include/linux/trace_seq.h @@ -8,11 +8,14 @@ /* * Trace sequences are used to allow a function to call several other functions - * to create a string of data to use (up to a max of PAGE_SIZE). + * to create a string of data to use. */ +#define TRACE_SEQ_BUFFER_SIZE (PAGE_SIZE * 2 - \ + (sizeof(struct seq_buf) + sizeof(size_t) + sizeof(int))) + struct trace_seq { - char buffer[PAGE_SIZE]; + char buffer[TRACE_SEQ_BUFFER_SIZE]; struct seq_buf seq; size_t readpos; int full; @@ -21,7 +24,7 @@ struct trace_seq { static inline void trace_seq_init(struct trace_seq *s) { - seq_buf_init(&s->seq, s->buffer, PAGE_SIZE); + seq_buf_init(&s->seq, s->buffer, TRACE_SEQ_BUFFER_SIZE); s->full = 0; s->readpos = 0; } diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 83393c65ec71..da837119a446 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3753,7 +3753,7 @@ static bool trace_safe_str(struct trace_iterator *iter, const char *str, /* OK if part of the temp seq buffer */ if ((addr >= (unsigned long)iter->tmp_seq.buffer) && - (addr < (unsigned long)iter->tmp_seq.buffer + PAGE_SIZE)) + (addr < (unsigned long)iter->tmp_seq.buffer + TRACE_SEQ_BUFFER_SIZE)) return true; /* Core rodata can not be freed */ @@ -6926,8 +6926,8 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, goto out; } - if (cnt >= PAGE_SIZE) - cnt = PAGE_SIZE - 1; + if (cnt >= TRACE_SEQ_BUFFER_SIZE) + cnt = TRACE_SEQ_BUFFER_SIZE - 1; /* reset all but tr, trace, and overruns */ trace_iterator_reset(iter); diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c index 7be97229ddf8..c158d65a8a88 100644 --- a/kernel/trace/trace_seq.c +++ b/kernel/trace/trace_seq.c @@ -13,9 +13,6 @@ * trace_seq_init() more than once to reset the trace_seq to start * from scratch. * - * The buffer size is currently PAGE_SIZE, although it may become dynamic - * in the future. - * * A write to the buffer will either succeed or fail. That is, unlike * sprintf() there will not be a partial write (well it may write into * the buffer but it wont update the pointers). This allows users to