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[146.241.109.224]) by smtp.gmail.com with ESMTPSA id d3sm524054wrx.28.2021.06.23.09.36.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Jun 2021 09:36:13 -0700 (PDT) Message-ID: <254a0b83518083416abdae4cd27659bc10760773.camel@redhat.com> Subject: Re: [PATCH 5.10 038/146] mptcp: do not warn on bad input from the network From: Paolo Abeni To: Pavel Machek , Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Mat Martineau , "David S. Miller" , Sasha Levin Date: Wed, 23 Jun 2021 18:36:12 +0200 In-Reply-To: <20210623142235.GA27348@amd> References: <20210621154911.244649123@linuxfoundation.org> <20210621154912.589676201@linuxfoundation.org> <20210623142235.GA27348@amd> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Wed, 2021-06-23 at 16:22 +0200, Pavel Machek wrote: > Hi! > > > From: Paolo Abeni > > > > [ Upstream commit 61e710227e97172355d5f150d5c78c64175d9fb2 ] > > > > warn_bad_map() produces a kernel WARN on bad input coming > > from the network. Use pr_debug() to avoid spamming the system > > log. > > So... we switched from WARN _ONCE_ to pr_debug, as many times as we > detect the problem. > > Should this be pr_debug_once? Thank you for double checking this! In the MPTCP code, we use pr_debug() statements as a debug tool, e.g. when enabled, it could print per-packet info with no restriction. There are (a few) similar use in the plain TCP code. pr_debug() is not supposed to be enabled on any production system, while the WARN_ONCE could trigger automated tools for irrelevant network noise. I thing pr_debug() is fine here. Cheers, Paolo