From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (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 6725281732; Fri, 22 Aug 2025 01:26:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755825990; cv=none; b=e5SvA2iiK5u3z4nwlCtsFtxuTAsxpF3xEdFW0BSpGJflKhlwkBKoA862IxwrUoUHyzzhzRVmQlPk7lxL2+JDe0LwwaXR5ETf2QP+dlBGKghDTPcbPTO5mddbIypNjRPR1vrOvcII9Q2YZry5TIYBy+rNBm90YnwWjuzlW5Udw8Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755825990; c=relaxed/simple; bh=dL+tNK8irqmkqr5Oj7Gsu1orlNCurPKsma4kH5E3iZk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=QL6K6uUlXgYYgA7XdSnj6ntNcjgC0/VFi4YlB9/h6+t1iTFDb81fGSR7yaQQZnGcZrge2EAEbiys+akaDFslP3qjWB7NjJNkuYk4F3pw0xBkjNMRDCNbkHBqAQ4DWEYN6PaSuqD9EqzoWEJOHryznORI7HsSxT9C8WL7GOoghd0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.216]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4c7MwJ0hx5zKHMtV; Fri, 22 Aug 2025 09:26:24 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.75]) by mail.maildlp.com (Postfix) with ESMTP id 93D721A1989; Fri, 22 Aug 2025 09:26:23 +0800 (CST) Received: from [10.67.110.36] (unknown [10.67.110.36]) by APP2 (Coremail) with SMTP id Syh0CgDX5LY+x6donji7EQ--.56706S2; Fri, 22 Aug 2025 09:26:23 +0800 (CST) Message-ID: <84a2f916-47c5-4c6f-9d36-771f60db35fc@huaweicloud.com> Date: Fri, 22 Aug 2025 09:26:22 +0800 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH -next v2] ftrace: Fix potential warning in trace_printk_seq during ftrace_dump To: Steven Rostedt Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Ingo Molnar , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250821021120.2986553-1-wutengda@huaweicloud.com> <20250821110503.5f5c3156@gandalf.local.home> Content-Language: en-US From: Tengda Wu In-Reply-To: <20250821110503.5f5c3156@gandalf.local.home> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CM-TRANSID:Syh0CgDX5LY+x6donji7EQ--.56706S2 X-Coremail-Antispam: 1UD129KBjvJXoW7AryDXF4rZFW5tw1kGw4xCrg_yoW8Aw1Dpr yfKFZrAFZ5JFWUtF1I9r1jyF1xt34ftry7Grs8Jr1rXrsxAryI9ryIyrnagryfA3s8Gr9a yF4Yy34Uuw17XFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUylb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x 0267AKxVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcVAKI48JMxkF7I0En4kS14v26r126r1DMxAIw28IcxkI7VAK I48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7 xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xII jxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAIw2 0EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x02 67AKxVWUJVW8JbIYCTnIWIevJa73UjIFyTuYvjxUwxhLUUUUU X-CM-SenderInfo: pzxwv0hjgdqx5xdzvxpfor3voofrz/ On 2025/8/21 23:05, Steven Rostedt wrote: > 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 I apologize, as this is a trace left over from the initial patch modification process. While working with the original code, I added an `if (ent)` branch directly to trace_printk_seq and later realized it could be merged with the previous `if (ent)` branch. However, I forgot to remove the now-redundant ent after the merge. I will correct this immediately and resend a new version. -- Tengda > > >> } >> touch_nmi_watchdog(); >> - >> - trace_printk_seq(&iter.seq); >> } >> >> if (!cnt)