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id S230243AbhCZSN4 (ORCPT ); Fri, 26 Mar 2021 14:13:56 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E8F096191A; Fri, 26 Mar 2021 18:13:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1616782436; bh=4xWEzinB4T56m3AW6X0p5tMskUl3gpqeuEz4IxAalT0=; h=In-Reply-To:References:Subject:From:Cc:To:Date:From; b=QkrmLuc0C0NmKfc2LAnmXlsoHEvKNKPPBQM68KiyxKMbgV5/e/FSqYnxUUtruhN39 WW6Awf7qh5Dw4HFWWbW1yOWm5Jv3c6MlWXMx2hDucpY7RWz0n06MJN1K/drNP6qEUs GCGAw6i1P8rL4W3mXwdzpZRzPManvWAjodCzN6i1LZuYPM2+L8yKsb0t5Cv5vDkVnZ NQTOZ6YOklBrnkoOXXPx2zkJeoNff4FSSw2ESanOvcwsBmks8uD5/+ojtrRJFAwT8F J+rqqgjHd7Ag+10DKLQL7dPh0RzTHu83J3V6gLnxwTxmxp+Xzga3JbGJR6NTOpWoxS v2wvPI4IB1r5w== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable In-Reply-To: <9b206c4d00dfe8b7f941260f18909914b2b2eecb.camel@suse.de> References: <20210205222644.2357303-9-saravanak@google.com> <20210210114435.122242-1-tudor.ambarus@microchip.com> <20210210114435.122242-2-tudor.ambarus@microchip.com> <9b206c4d00dfe8b7f941260f18909914b2b2eecb.camel@suse.de> Subject: Re: [PATCH] clk: Mark fwnodes when their clock provider is added From: Stephen Boyd Cc: nicolas.ferre@microchip.com, claudiu.beznea@microchip.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-clk@vger.kernel.org, devicetree@vger.kernel.org, linux-acpi@vger.kernel.org, geert@linux-m68k.org, kernel-team@android.com, linux-rpi-kernel To: Marek Szyprowski , Nicolas Saenz Julienne , Tudor Ambarus , corbet@lwn.net, frowand.list@gmail.com, gregkh@linuxfoundation.org, khilman@kernel.org, len.brown@intel.com, lenb@kernel.org, maz@kernel.org, mturquette@baylibre.com, pavel@ucw.cz, rafael@kernel.org, robh+dt@kernel.org, saravanak@google.com, tglx@linutronix.de, ulf.hansson@linaro.org Date: Fri, 26 Mar 2021 11:13:54 -0700 Message-ID: <161678243444.3012082.5031467952132861429@swboyd.mtv.corp.google.com> User-Agent: alot/0.9.1 Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Quoting Nicolas Saenz Julienne (2021-03-25 11:25:24) > On Thu, 2021-03-25 at 14:31 +0100, Marek Szyprowski wrote: > > Hi > >=20 > > On 10.02.2021 12:44, Tudor Ambarus wrote: > > > This is a follow-up for: > > > commit 3c9ea42802a1 ("clk: Mark fwnodes when their clock provider is = added/removed") > > >=20 > > > The above commit updated the deprecated of_clk_add_provider(), > > > but missed to update the preferred of_clk_add_hw_provider(). > > > Update it now. > > >=20 > > > Signed-off-by: Tudor Ambarus > >=20 > > This patch, which landed in linux-next as commit 6579c8d97ad7 ("clk:=20 > > Mark fwnodes when their clock provider is added") causes the following = > > NULL pointer dereference on Raspberry Pi 3b+ boards: > >=20 > > --->8--- > >=20 > > raspberrypi-firmware soc:firmware: Attached to firmware from=20 > > 2020-01-06T13:05:25 > > Unable to handle kernel NULL pointer dereference at virtual address=20 > > 0000000000000050 > > Mem abort info: > > =C2=A0=C2=A0 ESR =3D 0x96000004 > > =C2=A0=C2=A0 EC =3D 0x25: DABT (current EL), IL =3D 32 bits > > =C2=A0=C2=A0 SET =3D 0, FnV =3D 0 > > =C2=A0=C2=A0 EA =3D 0, S1PTW =3D 0 > > Data abort info: > > =C2=A0=C2=A0 ISV =3D 0, ISS =3D 0x00000004 > > =C2=A0=C2=A0 CM =3D 0, WnR =3D 0 > > [0000000000000050] user address but active_mm is swapper > > Internal error: Oops: 96000004 [#1] PREEMPT SMP > > Modules linked in: > > CPU: 0 PID: 10 Comm: kworker/0:1 Not tainted 5.12.0-rc4+ #2764 > > Hardware name: Raspberry Pi 3 Model B (DT) > > Workqueue: events deferred_probe_work_func > > pstate: 00000005 (nzcv daif -PAN -UAO -TCO BTYPE=3D--) > > pc : of_clk_add_hw_provider+0xac/0xe8 > > lr : of_clk_add_hw_provider+0x94/0xe8 > > sp : ffff8000130936b0 > > x29: ffff8000130936b0 x28: ffff800012494e04 > > x27: ffff00003b18cb05 x26: ffff00003aa5c010 > > x25: 0000000000000000 x24: 0000000000000000 > > x23: ffff00003aa1e380 x22: ffff8000106830d0 > > x21: ffff80001233f180 x20: 0000000000000018 > > x19: 0000000000000000 x18: ffff8000124d38b0 > > x17: 0000000000000013 x16: 0000000000000014 > > x15: ffff8000125758b0 x14: 00000000000184e0 > > x13: 000000000000292e x12: ffff80001258dd98 > > x11: 0000000000000001 x10: 0101010101010101 > > x9 : ffff80001233f288 x8 : 7f7f7f7f7f7f7f7f > > x7 : fefefefeff6c626f x6 : 5d636d8080808080 > > x5 : 00000000006d635d x4 : 0000000000000000 > > x3 : 0000000000000000 x2 : 540eb5edae191600 > > x1 : 0000000000000000 x0 : 0000000000000000 > > Call trace: > > =C2=A0=C2=A0of_clk_add_hw_provider+0xac/0xe8 > > =C2=A0=C2=A0devm_of_clk_add_hw_provider+0x5c/0xb8 > > =C2=A0=C2=A0raspberrypi_clk_probe+0x110/0x210 > > =C2=A0=C2=A0platform_probe+0x90/0xd8 > > =C2=A0=C2=A0really_probe+0x108/0x3c0 > > =C2=A0=C2=A0driver_probe_device+0x60/0xc0 > > =C2=A0=C2=A0__device_attach_driver+0x9c/0xd0 > > =C2=A0=C2=A0bus_for_each_drv+0x70/0xc8 > > =C2=A0=C2=A0__device_attach+0xec/0x150 > > =C2=A0=C2=A0device_initial_probe+0x10/0x18 > > =C2=A0=C2=A0bus_probe_device+0x94/0xa0 > > =C2=A0=C2=A0device_add+0x47c/0x780 > > =C2=A0=C2=A0platform_device_add+0x110/0x248 > > =C2=A0=C2=A0platform_device_register_full+0x120/0x150 > > =C2=A0=C2=A0rpi_firmware_probe+0x158/0x1f8 > > =C2=A0=C2=A0platform_probe+0x90/0xd8 > > =C2=A0=C2=A0really_probe+0x108/0x3c0 > > =C2=A0=C2=A0driver_probe_device+0x60/0xc0 > > =C2=A0=C2=A0__device_attach_driver+0x9c/0xd0 > > =C2=A0=C2=A0bus_for_each_drv+0x70/0xc8 > > =C2=A0=C2=A0__device_attach+0xec/0x150 > > =C2=A0=C2=A0device_initial_probe+0x10/0x18 > > =C2=A0=C2=A0bus_probe_device+0x94/0xa0 > > =C2=A0=C2=A0deferred_probe_work_func+0x70/0xa8 > > =C2=A0=C2=A0process_one_work+0x2a8/0x718 > > =C2=A0=C2=A0worker_thread+0x48/0x460 > > =C2=A0=C2=A0kthread+0x134/0x160 > > =C2=A0=C2=A0ret_from_fork+0x10/0x18 > > Code: b1006294 540000c0 b140069f 54000088 (3940e280) > > ---[ end trace 7ead5ec2f0c51cfe ]--- > >=20 > > This patch mainly revealed that clk/bcm/clk-raspberrypi.c driver calls = > > devm_of_clk_add_hw_provider(), with a device pointer, which has a NULL = > > dev->of_node. I'm not sure if adding a check for a NULL np in=20 > > of_clk_add_hw_provider() is a right fix, though. >=20 > I believe the right fix is not to call 'devm_of_clk_add_hw_provider()' if > 'pdev->dev.of_node =3D=3D NULL'. In such case, which is RPi3's, only the = CPU clock > is used, and it's defined and queried later through > devm_clk_hw_register_clkdev(). >=20 > @Marek, I don't mind taking care of it if it's OK with you. >=20 Ah I see this is related to the patch I just reviewed. Can you reference this in the commit text? And instead of putting the change into the clk provider let's check for NULL 'np' in of_clk_add_hw_provider() instead and return 0 if there's nothing to do. That way we don't visit this problem over and over again.