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[34.124.129.10]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-38e16e1d010sm1598056a91.0.2026.07.14.07.06.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Jul 2026 07:06:42 -0700 (PDT) Date: Tue, 14 Jul 2026 14:06:36 +0000 From: Pranjal Shrivastava To: weimin xiong Cc: Will Deacon , Robin Murphy , Joerg Roedel , Benjamin Gaignard , Rob Clark , linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org Subject: Re: [PATCH v1 0/4] iommu: Fix device lookup lifetime and probe cleanup Message-ID: References: <20260714060930.220277-1-xiongwm2026@163.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <20260714060930.220277-1-xiongwm2026@163.com> On Tue, Jul 14, 2026 at 02:09:26PM +0800, weimin xiong wrote: > Fix a few IOMMU driver lifetime and error-path issues found while > auditing fwnode-based device lookup and probe cleanup paths. > > The first three patches avoid deriving driver private data after > dropping the device reference returned by bus_find_device_by_fwnode(). > They also make the ARM SMMU v2 and VSI probe paths fail cleanly when the > IOMMU lookup fails. I'm not sure if that's really needed? All these drivers are doing is dropping the "extra" refcount (incremented by calling find_device) back to the state *before* the fwnode function call. If you find that this put_device caused the count to drop to 0, I believe that's the real problem/bug. These fwnode functions are usually called in probe and the refcount shouldn't be 0 inside probe. Could you share your observation / failing logs where this fails? Maybe something else is wrong with the system? Thanks, Praan