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Wysocki" , Danilo Krummrich , Saravana Kannan , stable@vger.kernel.org, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] driver core: Don't link the device to the bus until we're ready to probe Message-ID: <5ea67deb-e669-4faa-be47-b1b225f1194a@rowland.harvard.edu> References: <2026032114-unlocked-unmoving-091b@gregkh> <6ff1444b-f83e-47f6-ab0d-6745738523ba@rowland.harvard.edu> <6511a5b9-ac67-49a1-8336-3d2afaaab593@rowland.harvard.edu> <852cd509-4ce1-4b22-ab1f-b9b9bbf6a52e@rowland.harvard.edu> 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: On Fri, Mar 27, 2026 at 12:30:47PM -0700, Doug Anderson wrote: > > But why just in that one case? That's what I don't understand. If it's > > not okay to bind at this time on the driver-load path, why is it okay to > > bind on other pathways (such as bus.c:bind_store())? > > Ah, I see! > > Yeah, OK. I spent more time, and I think I've a patch that will > address things. I still like adding the "ready_to_probe" flag and > setting it in device_add() right before bus_probe_device(). ...but > I've changed where I'm testing this flag. Now I've got the test in > __driver_probe_device(), where I simply do: > > /* > * In device_add(), the "struct device" gets linked into the subsystem's > * list of devices and broadcast to userspace (via uevent) before we're > * quite ready to probe. Those open pathways to driver probe before > * we've finished enough of device_add() to reliably support probe. > * Detect this and tell other pathways to try again later. device_add() > * itself will also try to probe immediately after setting > * "ready_to_probe". > */ > if (!dev->ready_to_probe) > return dev_err_probe(dev, -EPROBE_DEFER, "Device not ready_to_probe"); > > I think that is more inline with your intuition that we should return > some sort of "try again" code when we end up with this situation. This > should also block _all_ probe paths safely by adding to the deferral > list (just in case) or returning -EAGAIN (in the case of > device_driver_attach()). > > Does that sound like what you're looking for? Yes, that's exactly what I was asking about. Let's see the complete patch! Alan Stern