Messages in this thread | | | From | Saravana Kannan <> | Date | Wed, 4 Aug 2021 14:47:24 -0700 | Subject | Re: [PATCH 1/2] irqchip: irq-meson-gpio: make it possible to build as a module |
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On Wed, Aug 4, 2021 at 11:20 AM Saravana Kannan <saravanak@google.com> wrote: > > On Wed, Aug 4, 2021 at 1:50 AM Marc Zyngier <maz@kernel.org> wrote: > > > > On Wed, 04 Aug 2021 02:36:45 +0100, > > Saravana Kannan <saravanak@google.com> wrote: > > > > Hi Saravana, > > > > Thanks for looking into this. > > You are welcome. I just don't want people to think fw_devlink is broken :) > > > > > [...] > > > > > > Saravana, could you please have a look from a fw_devlink perspective? > > > > > > Sigh... I spent several hours looking at this and wrote up an analysis > > > and then realized I might be looking at the wrong DT files. > > > > > > Marc, can you point me to the board file in upstream that corresponds > > > to the platform in which you see this issue? I'm not asking for [1], > > > but the actual final .dts (not .dtsi) file that corresponds to the > > > platform/board/system. > > > > The platform I can reproduce this on is described in > > arch/arm64/boot/dts/amlogic/meson-sm1-khadas-vim3l.dts. It is an > > intricate maze of inclusion, node merge and other DT subtleties. I > > suggest you look at the decompiled version to get a view of the > > result. > > Thanks. After decompiling it, it looks something like (stripped a > bunch of reg and address properties and added the labels back): > > eth_phy: mdio-multiplexer@4c000 { > compatible = "amlogic,g12a-mdio-mux"; > clocks = <0x02 0x13 0x1e 0x02 0xb1>; > clock-names = "pclk\0clkin0\0clkin1"; > mdio-parent-bus = <0x22>; > > ext_mdio: mdio@0 { > reg = <0x00>; > > ethernet-phy@0 { > max-speed = <0x3e8>; > interrupt-parent = <0x23>; > interrupts = <0x1a 0x08>; > phandle = <0x16>; > }; > }; > > int_mdio: mdio@1 { > ... > } > } > > And phandle 0x23 refers to the gpio_intc interrupt controller with the > modular driver. > > > > Based on your error messages, it's failing for mdio@0 which > > > corresponds to ext_mdio. But none of the board dts files in upstream > > > have a compatible property for "ext_mdio". Which means fw_devlink > > > _should_ propagate the gpio_intc IRQ dependency all the way up to > > > eth_phy. > > > > > > Also, in the failing case, can you run: > > > ls -ld supplier:* > > > > > > in the /sys/devices/....<something>/ folder that corresponds to the > > > "eth_phy: mdio-multiplexer@4c000" DT node and tell me what it shows? > > > > Here you go: > > > > root@tiger-roach:~# find /sys/devices/ -name 'supplier*'|grep -i mdio | xargs ls -ld > > lrwxrwxrwx 1 root root 0 Aug 4 09:47 /sys/devices/platform/soc/ff600000.bus/ff64c000.mdio-multiplexer/supplier:platform:ff63c000.system-controller:clock-controller -> ../../../../virtual/devlink/platform:ff63c000.system-controller:clock-controller--platform:ff64c000.mdio-multiplexer > > As we discussed over chat, this was taken after the mdio-multiplexer > driver "successfully" probes this device. This will cause > SYNC_STATE_ONLY device links created by fw_devlink to be deleted > (because they are useless after a device probes). So, this doesn't > show the info I was hoping to demonstrate. > > In any case, one can see that fw_devlink properly created the device > link for the clocks dependency. So fw_devlink is parsing this node > properly. But it doesn't create a similar probe order enforcing device > link between the mdio-multiplexer and the gpio_intc because the > dependency is only present in a grand child DT node (ethernet-phy@0 > under ext_mdio). So fw_devlink is working as intended. > > I spent several hours squinting at the code/DT yesterday. Here's what > is going on and causing the problem: > > The failing driver in this case is > drivers/net/mdio/mdio-mux-meson-g12a.c. And the only DT node it's > handling is what I pasted above in this email. In the failure case, > the call flow is something like this: > > g12a_mdio_mux_probe() > -> mdio_mux_init() > -> of_mdiobus_register(ext_mdio DT node) > -> of_mdiobus_register_phy(ext_mdio DT node) > -> several calls deep fwnode_mdiobus_phy_device_register(ethernet_phy DT node) > -> Tried to get the IRQ listed in ethernet_phy and fails with > -EPROBE_DEFER because the IRQ driver isn't loaded yet. > > The error is propagated correctly all the way up to of_mdiobus_register(), but > mdio_mux_init() ignores the -EPROBE_DEFER from of_mdiobus_register() and just > continues on with the rest of the stuff and returns success as long as > one of the child nodes (in this case int_mdio) succeeds. > > Since the probe returns 0 without really succeeding, networking stuff > just fails badly after this. So, IMO, the real problem is with > mdio_mux_init() not propagating up the -EPROBE_DEFER. I gave Marc a > quick hack (pasted at the end of this email) to test my theory and he > confirmed that it fixes the issue (a few deferred probes later, things > work properly). > > Andrew, I don't see any good reason for mdio_mux_init() not > propagating the errors up correctly (at least for EPROBE_DEFER). I'll > send a patch to fix this. Please let me know if there's a reason it > has to stay as-is.
I sent out the proper fix as a series: https://lore.kernel.org/lkml/20210804214333.927985-1-saravanak@google.com/T/#t
Marc, can you give it a shot please?
-Saravana
> > -Saravana > > index 110e4ee85785..d973a267151f 100644 > --- a/drivers/net/mdio/mdio-mux.c > +++ b/drivers/net/mdio/mdio-mux.c > @@ -170,6 +170,9 @@ int mdio_mux_init(struct device *dev, > child_bus_node); > mdiobus_free(cb->mii_bus); > devm_kfree(dev, cb); > + /* Not a final fix. I think it can cause UAF issues. */ > + mdio_mux_uninit(pb); > + return r; > } else { > cb->next = pb->children; > pb->children = cb;
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