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[146.241.59.53]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-390cd866f0asm2045732f8f.12.2025.02.25.03.53.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 25 Feb 2025 03:53:50 -0800 (PST) Message-ID: Date: Tue, 25 Feb 2025 12:53:49 +0100 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next 5/7] netconsole: add task name to extra data fields To: Breno Leitao , Simon Horman Cc: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Jonathan Corbet , Shuah Khan , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-team@meta.com References: <20250221-netcons_current-v1-0-21c86ae8fc0d@debian.org> <20250221-netcons_current-v1-5-21c86ae8fc0d@debian.org> <20250225101910.GM1615191@kernel.org> <20250225-doberman-of-scientific-champagne-640c69@leitao> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20250225-doberman-of-scientific-champagne-640c69@leitao> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/25/25 12:17 PM, Breno Leitao wrote: > On Tue, Feb 25, 2025 at 10:19:10AM +0000, Simon Horman wrote: >> On Fri, Feb 21, 2025 at 05:52:10AM -0800, Breno Leitao wrote: >>> This is the core patch for this whole patchset. Add support for >>> including the current task's name in netconsole's extra data output. >>> This adds a new append_taskname() function that writes the task name >>> (from current->comm) into the target's extradata buffer, similar to how >>> CPU numbers are handled. >>> >>> The task name is included when the SYSDATA_TASKNAME field is set, >>> appearing in the format "taskname=" in the output. This additional >>> context can help with debugging by showing which task generated each >>> console message. >>> >>> Signed-off-by: Breno Leitao >>> --- >>> drivers/net/netconsole.c | 14 +++++++++++++- >>> 1 file changed, 13 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c >>> index 5a29144ae37ee7b487b1a252b0f2ce8574f9cefa..625f4c0be11d8deb454139b1c526abc842697219 100644 >>> --- a/drivers/net/netconsole.c >>> +++ b/drivers/net/netconsole.c >>> @@ -1179,12 +1179,22 @@ static int append_cpu_nr(struct netconsole_target *nt, int offset) >>> raw_smp_processor_id()); >>> } >>> >>> +static int append_taskname(struct netconsole_target *nt, int offset) >>> +{ >>> + if (WARN_ON_ONCE(!current)) >>> + return 0; >> >> Hi Breno, >> >> I gather that theoretically this could occur, but it isn't expected >> to happen in practice. Is that right? > > That's correct. `current` isn't expected to be NULL in practice. > I've been running this code on several servers for days and have never > encountered this warning. > > While the taskname feature isn't enabled during early boot, netconsole > might be active at that time, which is why I exercised extra caution > here. So `current` can't be NULL here. I think it's better to drop such check, it's presence would be misleading. i.e. like adding checks for UDP stack being initialized before calling send_msg_fragmented() Cheers, Paolo