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Tue, 05 Aug 2025 14:20:57 +0100 Date: Tue, 05 Aug 2025 14:20:52 +0100 Message-ID: <86fre5aoqz.wl-maz@kernel.org> From: Marc Zyngier To: Sasha Levin Cc: patches@lists.linux.dev, stable@vger.kernel.org, Lorenzo Pieralisi , Bjorn Helgaas , toan@os.amperecomputing.com, kwilczynski@kernel.org, mani@kernel.org, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH AUTOSEL 6.16-6.6] PCI: xgene-msi: Resend an MSI racing with itself on a different CPU In-Reply-To: <20250805130945.471732-59-sashal@kernel.org> References: <20250805130945.471732-1-sashal@kernel.org> <20250805130945.471732-59-sashal@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: sashal@kernel.org, patches@lists.linux.dev, stable@vger.kernel.org, lpieralisi@kernel.org, bhelgaas@google.com, toan@os.amperecomputing.com, kwilczynski@kernel.org, mani@kernel.org, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250805_062101_305962_5F3AE42C X-CRM114-Status: GOOD ( 16.72 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 05 Aug 2025 14:09:34 +0100, Sasha Levin wrote: > > From: Marc Zyngier > > [ Upstream commit 3cc8f625e4c6a0e9f936da6b94166e62e387fe1d ] > > Since changing the affinity of an MSI really is about changing > the target address and that it isn't possible to mask an individual > MSI, it is completely possible for an interrupt to race with itself, > usually resulting in a lost interrupt. > > Paper over the design blunder by informing the core code of this > sad state of affairs. > > Signed-off-by: Marc Zyngier > Signed-off-by: Lorenzo Pieralisi > Signed-off-by: Bjorn Helgaas > Link: https://lore.kernel.org/r/20250708173404.1278635-11-maz@kernel.org > Signed-off-by: Sasha Levin > --- > > LLM Generated explanations, may be completely bogus: s/may be//. It is an amusing read though, specially when quoting totally unrelated patches, so thumbs up for the comical value. But I'm not even going to entertain explaining *why* backporting this patch on its own is nonsense. Reading the original series should be enlightening enough. M. -- Without deviation from the norm, progress is not possible.