Re: [PATCH v2 resend] driver core: Make deferred_probe_timeout default a Kconfig option

[Hans de Goede]

Hi All,

On 14-Mar-26 09:49, Hans de Goede wrote:
> Code using driver_deferred_probe_check_state() differs from most
> EPROBE_DEFER handling in the kernel. Where other EPROBE_DEFER handling
> (e.g. clks, gpios and regulators) waits indefinitely for suppliers to
> show up, code using driver_deferred_probe_check_state() will fail
> after the deferred_probe_timeout.
> 
> This is a problem for generic distro kernels which want to support many
> boards using a single kernel build. These kernels want as much drivers to
> be modular as possible. The initrd also should be as small as possible,
> so the initrd will *not* have drivers not needing to get the rootfs.
> 
> Combine this with waiting for a full-disk encryption password in
> the initrd and it is pretty much guaranteed that the default 10s timeout
> will be hit, causing probe() failures when drivers on the rootfs happen
> to get modprobe-d before other rootfs modules providing their suppliers.
> 
> Make the default timeout configurable from Kconfig to allow distro kernel
> configs where many of the supplier drivers are modules to set the default
> through Kconfig.
> 
> While at it document that a value of -1 can be used to disable the timeout
> (wait indefinitely).
> 
> Acked-by: Saravana Kannan <saravanak@xxxxxxxxxx>
> Signed-off-by: Hans de Goede <johannes.goede@xxxxxxxxxxxxxxxx>

gentle ping ?

AFAICT there is no reason to not merge this ?

Regards,

Hans



> ---
> Changes in v2:
> - Remove unnecessary addition of "if (driver_deferred_probe_timeout < 0)"
>   check
> - Add Acked-by from Saravana
> ---
> Resending as this one seems to have fallen through the cracks.
> ---
>  Documentation/admin-guide/kernel-parameters.txt | 2 +-
>  drivers/base/Kconfig                            | 9 +++++++++
>  drivers/base/dd.c                               | 6 +-----
>  3 files changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index aa0031108bc1..d26957741713 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1250,7 +1250,7 @@ Kernel parameters
>  			out hasn't expired, it'll be restarted by each
>  			successful driver registration. This option will also
>  			dump out devices still on the deferred probe list after
> -			retrying.
> +			retrying. Set to -1 to wait indefinitely.
>  
>  	delayacct	[KNL] Enable per-task delay accounting
>  
> diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
> index 1786d87b29e2..f7d385cbd3ba 100644
> --- a/drivers/base/Kconfig
> +++ b/drivers/base/Kconfig
> @@ -73,6 +73,15 @@ config DEVTMPFS_SAFE
>  	  with the PROT_EXEC flag. This can break, for example, non-KMS
>  	  video drivers.
>  
> +config DRIVER_DEFERRED_PROBE_TIMEOUT
> +	int "Default value for deferred_probe_timeout"
> +	default 0 if !MODULES
> +	default 10 if MODULES
> +	help
> +	  Set the default value for the deferred_probe_timeout kernel parameter.
> +	  See Documentation/admin-guide/kernel-parameters.txt for a description
> +	  of the deferred_probe_timeout kernel parameter.
> +
>  config STANDALONE
>  	bool "Select only drivers that don't need compile-time external firmware"
>  	default y
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index bea8da5f8a3a..2f358e29e0e8 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -257,11 +257,7 @@ static int deferred_devs_show(struct seq_file *s, void *data)
>  }
>  DEFINE_SHOW_ATTRIBUTE(deferred_devs);
>  
> -#ifdef CONFIG_MODULES
> -static int driver_deferred_probe_timeout = 10;
> -#else
> -static int driver_deferred_probe_timeout;
> -#endif
> +static int driver_deferred_probe_timeout = CONFIG_DRIVER_DEFERRED_PROBE_TIMEOUT;
>  
>  static int __init deferred_probe_timeout_setup(char *str)
>  {