From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) (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 07BB625DAE7; Thu, 21 Aug 2025 15:05:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755788710; cv=none; b=fJqvXXtmgYzmGTk4u75zV/9xmwTvgv2ILo2ec34PdI1WECJcR+gz6SzWY+HaSKok7NZWgDm5XSgU9emTaUdGdCOHamN3ToapfsM40jVzqKniu+HMv5eFTP6kqjxHGEYJ9V/Gz7KqhtdqStOaX1weUHZhy4IWXi5S4yAH7OVgtXc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755788710; c=relaxed/simple; bh=bJQig0T9oS6xig+yQQJGTH945hEMJoQh0QjDQ23dq8g=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Mmj5uPU3Uv3/av8VhjjWmOADtnzl2XvxPCgfg5o7zvIlchX7GiOsZVw9O742qrj7JrzhRsaQyjk9+rdIY76VxXYSxpTQFpAhr8ZU/V9tSbHacCKbUDNMwqQOq3s9B3mfU8plaC3iF9PkQLJZAoaoMrWY87QYeFz5EgbmzZcPxqs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; arc=none smtp.client-ip=216.40.44.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Received: from omf16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id E21D41A03E6; Thu, 21 Aug 2025 15:05:00 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf16.hostedemail.com (Postfix) with ESMTPA id DE2272000E; Thu, 21 Aug 2025 15:04:58 +0000 (UTC) Date: Thu, 21 Aug 2025 11:05:03 -0400 From: Steven Rostedt To: Tengda Wu Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Ingo Molnar , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH -next v2] ftrace: Fix potential warning in trace_printk_seq during ftrace_dump Message-ID: <20250821110503.5f5c3156@gandalf.local.home> In-Reply-To: <20250821021120.2986553-1-wutengda@huaweicloud.com> References: <20250821021120.2986553-1-wutengda@huaweicloud.com> X-Mailer: Claws Mail 3.20.0git84 (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 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: DE2272000E X-Stat-Signature: w3ibgc48qu3dkmyw4ekyfohtqiqw1x79 X-Rspamd-Server: rspamout06 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX18ThLyse5WuRnvVDb7JRaiuDEqLg6xGPpI= X-HE-Tag: 1755788698-787842 X-HE-Meta: U2FsdGVkX1+e0KzmUl1+S6s7g6fTli/DKzqp5x5YkgvaM61Vjs8OSC5PWmAg3nDZkm2WHiZfH7k9N4FNZM2AdqdutQI4YlIl2thCFlcahyFb1NewzHWFPgCeQ5y7RcDznNC9hV+ja6I4yAMIONF2VIUITjXNveED/FD5ahoJtEgp6J2SmheC9l+9l1cXiluVneh7+DEeokFygg76ZnGeQ6wUl06GOVJDlixE0bVcofgDgt5yuzivSv8G5NdMe7FJnnnrslS4KZNRBujc5rY0ZUE7dhns9MDbRe4ijlKykyHLMEPkK+qZE6F5iJV1DBkdRx8tGIOixbxBzJC9e3Xh+S/Et33vKOyp On Thu, 21 Aug 2025 02:11:20 +0000 Tengda Wu wrote: tested this and was writing the change log for the pull request when I realized an issue. > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 4283ed4e8f59..b4cec22753ea 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -10617,6 +10617,7 @@ static void ftrace_dump_one(struct trace_array *tr, enum ftrace_dump_mode dump_m > */ > > while (!trace_empty(&iter)) { > + void *ent; > > if (!cnt) > printk(KERN_TRACE "---------------------------------\n"); > @@ -10625,17 +10626,18 @@ static void ftrace_dump_one(struct trace_array *tr, enum ftrace_dump_mode dump_m > > trace_iterator_reset(&iter); > iter.iter_flags |= TRACE_FILE_LAT_FMT; > + ent = trace_find_next_entry_inc(&iter); > > - if (trace_find_next_entry_inc(&iter) != NULL) { > + if (ent) { Why do we need "ent"? > int ret; > > ret = print_trace_line(&iter); > if (ret != TRACE_TYPE_NO_CONSUME) > trace_consume(&iter); > + > + trace_printk_seq(&iter.seq); Isn't just moving trace_printk_seq() enough? The code is no different with or without the "ent" as "ent" is not used in the if block. -- Steve > } > touch_nmi_watchdog(); > - > - trace_printk_seq(&iter.seq); > } > > if (!cnt)