All of lore.kernel.org
 help / color / mirror / Atom feed
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: kvm@vger.kernel.org, "Rafael J. Wysocki" <rafael@kernel.org>
Subject: Re: [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind
Date: Tue, 8 Jun 2021 08:47:19 +0200	[thread overview]
Message-ID: <YL8SdymSgn9HHRcw@kroah.com> (raw)
In-Reply-To: <3-v1-324b2038f212+1041f1-vfio3a_jgg@nvidia.com>

On Mon, Jun 07, 2021 at 09:55:45PM -0300, Jason Gunthorpe wrote:
> Currently really_probe() returns 1 on success and 0 if the probe() call
> fails. This return code arrangement is designed to be useful for
> __device_attach_driver() which is walking the device list and trying every
> driver. 0 means to keep trying.
> 
> However, it is not useful for the other places that call through to
> really_probe() that do actually want to see the probe() return code.
> 
> For instance bind_store() would be better to return the actual error code
> from the driver's probe method, not discarding it and returning -ENODEV.

Why does that matter?  Why does it need to know this?

> Reorganize things so that really_probe() always returns an error code on
> failure and 0 on success. Move the special code for device list walking
> into the walker callback __device_attach_driver() and trigger it based on
> an output flag from really_probe(). Update the rest of the API surface to
> return a normal -ERR or 0 on success.
> 
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
>  drivers/base/bus.c |  6 +----
>  drivers/base/dd.c  | 61 ++++++++++++++++++++++++++++++----------------
>  2 files changed, 41 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/base/bus.c b/drivers/base/bus.c
> index 36d0c654ea6124..03591f82251302 100644
> --- a/drivers/base/bus.c
> +++ b/drivers/base/bus.c
> @@ -212,13 +212,9 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf,
>  	dev = bus_find_device_by_name(bus, NULL, buf);
>  	if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
>  		err = device_driver_attach(drv, dev);
> -
> -		if (err > 0) {
> +		if (!err) {
>  			/* success */
>  			err = count;
> -		} else if (err == 0) {
> -			/* driver didn't accept device */
> -			err = -ENODEV;
>  		}
>  	}
>  	put_device(dev);
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index c1a92cff159873..7fb58e6219b255 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -513,7 +513,13 @@ static ssize_t state_synced_show(struct device *dev,
>  }
>  static DEVICE_ATTR_RO(state_synced);
>  
> -static int really_probe(struct device *dev, struct device_driver *drv)
> +enum {
> +	/* Set on output if the -ERR has come from a probe() function */
> +	PROBEF_DRV_FAILED = 1 << 0,
> +};
> +
> +static int really_probe(struct device *dev, struct device_driver *drv,
> +			unsigned int *flags)

Ugh, no, please no functions with random "flags" in them, that way lies
madness and unmaintainable code for decades to come.

Especially as I have no idea what this is trying to solve here at all...

greg k-h

  parent reply	other threads:[~2021-06-08  6:47 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-08  0:55 [PATCH 00/10] Allow mdev drivers to directly create the vfio_device Jason Gunthorpe
2021-06-08  0:55 ` [Intel-gfx] " Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 01/10] driver core: Do not continue searching for drivers if deferred probe is used Jason Gunthorpe
2021-06-08  5:51   ` Christoph Hellwig
2021-06-08  6:44   ` Greg Kroah-Hartman
2021-06-08 12:16     ` Jason Gunthorpe
2021-06-08 13:13       ` Greg Kroah-Hartman
2021-06-08 13:53         ` Jason Gunthorpe
2021-06-08  7:35   ` Greg Kroah-Hartman
2021-06-08 12:17     ` Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 02/10] driver core: Pull required checks into driver_probe_device() Jason Gunthorpe
2021-06-08  5:59   ` Christoph Hellwig
2021-06-08 12:21     ` Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind Jason Gunthorpe
2021-06-08  6:07   ` Christoph Hellwig
2021-06-08 23:53     ` Jason Gunthorpe
2021-06-08  6:47   ` Greg Kroah-Hartman [this message]
2021-06-08 12:30     ` Jason Gunthorpe
2021-06-08 13:16       ` Greg Kroah-Hartman
2021-06-08 14:03         ` Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 04/10] driver core: Don't return EPROBE_DEFER to userspace during " Jason Gunthorpe
2021-06-08  6:14   ` Christoph Hellwig
2021-06-08  7:37   ` Greg Kroah-Hartman
2021-06-08  0:55 ` [PATCH 05/10] driver core: Export device_driver_attach() Jason Gunthorpe
2021-06-08  6:19   ` Christoph Hellwig
2021-06-08 12:33     ` Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 06/10] vfio/mdev: Remove CONFIG_VFIO_MDEV_DEVICE Jason Gunthorpe
2021-06-08  0:55   ` [Intel-gfx] " Jason Gunthorpe
2021-06-08  6:20   ` Christoph Hellwig
2021-06-08  6:20     ` [Intel-gfx] " Christoph Hellwig
2021-06-11 12:40   ` Cornelia Huck
2021-06-11 12:40     ` [Intel-gfx] " Cornelia Huck
2021-06-14 12:35     ` Jason Gunthorpe
2021-06-14 12:35       ` [Intel-gfx] " Jason Gunthorpe
2021-06-14 12:35       ` Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 07/10] vfio/mdev: Allow the mdev_parent_ops to specify the device driver to bind Jason Gunthorpe
2021-06-08  6:21   ` Christoph Hellwig
2021-06-08  0:55 ` [PATCH 08/10] vfio/mtty: Convert to use vfio_register_group_dev() Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 09/10] vfio/mdpy: " Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 10/10] vfio/mbochs: " Jason Gunthorpe
2021-06-08  6:22 ` [PATCH 00/10] Allow mdev drivers to directly create the vfio_device Christoph Hellwig
2021-06-08  6:22   ` [Intel-gfx] " Christoph Hellwig
2021-06-14 14:34 ` Kirti Wankhede
2021-06-14 14:34   ` [Intel-gfx] " Kirti Wankhede
2021-06-14 14:34   ` Kirti Wankhede
2021-06-14 14:36   ` Jason Gunthorpe
2021-06-14 14:36     ` [Intel-gfx] " Jason Gunthorpe
2021-06-14 14:36     ` Jason Gunthorpe
2021-06-14 15:08 Allow mdev drivers to directly create the vfio_device (v2 / alternative) Christoph Hellwig
2021-06-14 15:08 ` [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind Christoph Hellwig
2021-06-15  5:18   ` Greg Kroah-Hartman
2021-06-15  5:18     ` Greg Kroah-Hartman
2021-06-15 10:31   ` Cornelia Huck
2021-06-15 10:31     ` Cornelia Huck
2021-06-15 13:35 Allow mdev drivers to directly create the vfio_device (v3) Christoph Hellwig
2021-06-15 13:35 ` [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind Christoph Hellwig
2021-06-17 14:22 Allow mdev drivers to directly create the vfio_device (v4) Christoph Hellwig
2021-06-17 14:22 ` [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YL8SdymSgn9HHRcw@kroah.com \
    --to=gregkh@linuxfoundation.org \
    --cc=jgg@nvidia.com \
    --cc=kvm@vger.kernel.org \
    --cc=rafael@kernel.org \
    --subject='Re: [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.