From patchwork Tue Mar 5 03:34:33 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13581578 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 1860E2F44; Tue, 5 Mar 2024 03:32:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709609566; cv=none; b=Np7rGY5lTwivMX9bVDpwPlf6ryIDGgZNOZKLl++6BrGZKXxmlf1ZkyFhOwkt3X8anBJBks1IDNkLi48UDRzrrk8AEUZsfaBOh7D/1RQZJ4QlyFMFPLdtqQaHaAV99IRJuZlm6OUBEmIO6O2iigIayMrNBs/JKXHucfUahYVz86Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709609566; c=relaxed/simple; bh=cX8NBhzPtSej8jgrGTppfGMMCbZxG13SiFGh+FuLuUo=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type; b=Qb5gD+2OjRWr6kTT2x4WS5pFBXjuKe6n/wK7XHUbRGoWv1BysMpOUR8w9Go+01M+uRpQIRf2YhPGhaQqYThiJBwk2ngXKoN6j+1YB7U5faPpyTGKDvPhym47UMHisuZxDXtfFjwi4BToIR9J0Xs0Ovwo+kgryCoAUmf/JGoy9g4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id D14BDC43390; Tue, 5 Mar 2024 03:32:44 +0000 (UTC) Date: Mon, 4 Mar 2024 22:34:33 -0500 From: Steven Rostedt To: LKML , Linux Trace Kernel Cc: Masami Hiramatsu , Mathieu Desnoyers , Linus Torvalds , Sachin Sant Subject: [PATCH v2] tracing: Limit trace_marker writes to just 4K Message-ID: <20240304223433.4ba47dff@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)" Limit the max print event of trace_marker to just 4K string size. This must also be less than the amount that can be held by a trace_seq along with the text that is before the output (like the task name, PID, CPU, state, etc). As trace_seq is made to handle large events (some greater than 4K). Make the max size of a trace_marker write event be 4K which is guaranteed to fit in the trace_seq buffer. Suggested-by: Mathieu Desnoyers Signed-off-by: Steven Rostedt (Google) Reviewed-by: Mathieu Desnoyers Reviewed-by: Masami Hiramatsu (Google) --- Changes since v1: https://lore.kernel.org/linux-trace-kernel/20240304192710.4c99677c@gandalf.local.home/ - Just make the max limit 4K and not half of the trace_seq size. The trace_seq is already made to handle events greater than 4k. kernel/trace/trace.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8198bfc54b58..d16b95ca58a7 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -7293,6 +7293,8 @@ tracing_free_buffer_release(struct inode *inode, struct file *filp) return 0; } +#define TRACE_MARKER_MAX_SIZE 4096 + static ssize_t tracing_mark_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *fpos) @@ -7320,6 +7322,9 @@ tracing_mark_write(struct file *filp, const char __user *ubuf, if ((ssize_t)cnt < 0) return -EINVAL; + if (cnt > TRACE_MARKER_MAX_SIZE) + cnt = TRACE_MARKER_MAX_SIZE; + meta_size = sizeof(*entry) + 2; /* add '\0' and possible '\n' */ again: size = cnt + meta_size; @@ -7328,11 +7333,6 @@ tracing_mark_write(struct file *filp, const char __user *ubuf, if (cnt < FAULTED_SIZE) size += FAULTED_SIZE - cnt; - if (size > TRACE_SEQ_BUFFER_SIZE) { - cnt -= size - TRACE_SEQ_BUFFER_SIZE; - goto again; - } - buffer = tr->array_buffer.buffer; event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, size, tracing_gen_ctx());