linux-kernel - Re: [PATCH v2] driver core: Fix bus

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <b1100fe9-9cf4-26e0-7fa5-b40f6a25ef44@samsung.com>
Date:   Thu, 25 Aug 2022 11:22:51 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     "Isaac J. Manjarres" <isaacmanjarres@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Russell King <rmk+kernel@....linux.org.uk>
Cc:     Saravana Kannan <saravanak@...gle.com>, stable@...nel.org,
        Guenter Roeck <linux@...ck-us.net>, kernel-team@...roid.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] driver core: Fix bus_type.match() error handling

On 15.08.2022 23:19, Isaac J. Manjarres wrote:
> Both __device_attach_driver() and __driver_attach() check the return
> code of the bus_type.match() function to see if the device needs to be
> added to the deferred probe list. After adding the device to the list,
> the logic attempts to bind the device to the driver anyway, as if the
> device had matched with the driver, which is not correct.
>
> If __device_attach_driver() detects that the device in question is not
> ready to match with a driver on the bus, then it doesn't make sense for
> the device to attempt to bind with the current driver or continue
> attempting to match with any of the other drivers on the bus. So, update
> the logic in __device_attach_driver() to reflect this.
>
> If __driver_attach() detects that a driver tried to match with a device
> and that results in any error, then the driver should not attempt to bind
> with the device. However, the driver can still attempt to match and bind
> with other devices on the bus, as drivers can be bound to multiple
> devices. So, update the logic in __driver_attach() to reflect this.
>
> Cc: Saravana Kannan <saravanak@...gle.com>
> Cc: stable@...nel.org
> Fixes: 656b8035b0ee ("ARM: 8524/1: driver cohandle -EPROBE_DEFER from bus_type.match()")
> Reported-by: Guenter Roeck <linux@...ck-us.net>
> Signed-off-by: Isaac J. Manjarres <isaacmanjarres@...gle.com>

This fixes the boot issue observed on Qualcomm APQ8016 based DragonBoard 
410c, which I've missed while testing the "amba: Remove deferred device 
addition" patch. Feel free to add:

Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>

> ---
>   drivers/base/dd.c | 16 +++++++++++++++-
>   1 file changed, 15 insertions(+), 1 deletion(-)
>
> v1 -> v2:
> - Fixed the logic in __driver_attach() to allow a driver to continue
>    attempting to match and bind with devices in case of any error, not
>    just probe deferral.
>
> Guenter,
>
> Can you please give test this patch to make sure it still works for you?
>
> Thanks,
> Isaac
>
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 70f79fc71539..453eb19a9a27 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -881,6 +881,11 @@ static int __device_attach_driver(struct device_driver *drv, void *_data)
>   		dev_dbg(dev, "Device match requests probe deferral\n");
>   		dev->can_match = true;
>   		driver_deferred_probe_add(dev);
> +		/*
> +		 * Device can't match with a driver right now, so don't attempt
> +		 * to match or bind with other drivers on the bus.
> +		 */
> +		return ret;
>   	} else if (ret < 0) {
>   		dev_dbg(dev, "Bus failed to match device: %d\n", ret);
>   		return ret;
> @@ -1120,9 +1125,18 @@ static int __driver_attach(struct device *dev, void *data)
>   		dev_dbg(dev, "Device match requests probe deferral\n");
>   		dev->can_match = true;
>   		driver_deferred_probe_add(dev);
> +		/*
> +		 * Driver could not match with device right now, but may match
> +		 * with another device on the bus.
> +		 */
> +		return 0;
>   	} else if (ret < 0) {
>   		dev_dbg(dev, "Bus failed to match device: %d\n", ret);
> -		return ret;
> +		/*
> +		 * Driver could not match with device, but may match with
> +		 * another device on the bus.
> +		 */
> +		return 0;
>   	} /* ret > 0 means positive match */
>   
>   	if (driver_allows_async_probing(drv)) {

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland