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[174.249.144.35]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-12c346fb031sm15979260c88.13.2026.04.13.19.25.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Apr 2026 19:25:51 -0700 (PDT) Message-ID: <32dafe85-d6bf-4f64-a9f7-124d0bd677d5@gmail.com> Date: Mon, 13 Apr 2026 19:25:49 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next] net: shaper: Reject zero weight in shaper config To: Jakub Kicinski Cc: netdev@vger.kernel.org, ast@fiberby.net, chuck.lever@oracle.com, davem@davemloft.net, donald.hunter@gmail.com, edumazet@google.com, horms@kernel.org, linux-kernel@vger.kernel.org, matttbe@kernel.org, pabeni@redhat.com References: <20260410225123.2341672-1-mohsin.bashr@gmail.com> <20260413145039.43f7b162@kernel.org> Content-Language: en-US From: Mohsin Bashir In-Reply-To: <20260413145039.43f7b162@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 4/13/26 2:50 PM, Jakub Kicinski wrote: > On Fri, 10 Apr 2026 15:51:23 -0700 Mohsin Bashir wrote: >> A zero weight is meaningless for DWRR scheduling and can cause >> starvation of the affected node. Add a min-value constraint to >> the weight attribute in the net_shaper netlink spec so that zero >> is rejected at the netlink policy level. >> >> Found while prototyping a new driver, existing drivers are not >> affected. > > AI review points out that if the netlink attr is not present core will > leave the DWRR weight as 0 in the struct. I guess we need to think this > thru a little more carefully. What should the "default" weight be? > What if user specifies weights only for subset of leaves? > > This part of the uAPI seems under-defined. > > Maybe a better adjustment would be to make core set the weight to 1 > automatically if the user has not defined it? Only when sending it to > the driver tho, because we'd still want it to not be reported back to > user space. Not sure how hairy it'd get code-wise. Interesting!! Let me look at the big picture here and re-spin.