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Wed, 06 May 2026 07:22:59 -0700 (PDT) Received: from FV6GYCPJ69 ([2001:1ae9:6084:ab00:8c0b:afdd:3d9d:e976]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48e53907e8asm50107515e9.13.2026.05.06.07.22.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 May 2026 07:22:58 -0700 (PDT) Date: Wed, 6 May 2026 16:22:57 +0200 From: Jiri Pirko To: Jason Gunthorpe Cc: linux-rdma@vger.kernel.org, leon@kernel.org, mrgolin@amazon.com, gal.pressman@linux.dev, sleybo@amazon.com, parav@nvidia.com, mbloch@nvidia.com, yanjun.zhu@linux.dev, marco.crivellari@suse.com, roman.gushchin@linux.dev, phaddad@nvidia.com, lirongqing@baidu.com, ynachum@amazon.com, huangjunxian6@hisilicon.com, kalesh-anakkur.purayil@broadcom.com, ohartoov@nvidia.com, michaelgur@nvidia.com, shayd@nvidia.com, edwards@nvidia.com, sriharsha.basavapatna@broadcom.com, andrew.gospodarek@broadcom.com, selvin.xavier@broadcom.com Subject: Re: [PATCH rdma-next v3 17/17] RDMA/uverbs: Track attr consumption and warn on unused attrs Message-ID: References: <20260504135731.2345383-1-jiri@resnulli.us> <20260504135731.2345383-18-jiri@resnulli.us> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Wed, May 06, 2026 at 03:56:23PM +0200, jgg@ziepe.ca wrote: >On Mon, May 04, 2026 at 03:57:31PM +0200, Jiri Pirko wrote: >> From: Jiri Pirko >> >> Catch userspace passing attributes that nothing in the kernel >> reads which would be a sign that the driver doesn't support >> a feature, an attr was forgotten in a refactor, or userspace is buggy. >> UHW and PTR_OUT attrs are exempt; destroy attrs are marked consumed by >> the framework. Gate on CONFIG_DEBUG_KERNEL to avoid overhead on >> production kernels. > >This is maybe interesting debugging for a version matched rdma-core > >But the idea the kernel ignores an attribute is part of the protocol, I'm okay to drop this patch then. >if the attribute is marked mandatory by userspace then the kernel will >fail the system call. > >I don't remember how often this ends up being used, and I think it is >a bit rare, but it is there. > >Jason