diff mbox series

[v2,1/2] PCI: Convert to device_create_managed_software_node()

Message ID 20210930121246.22833-2-heikki.krogerus@linux.intel.com
State New
Headers show
Series [v2,1/2] PCI: Convert to device_create_managed_software_node() | expand

Commit Message

Heikki Krogerus Sept. 30, 2021, 12:12 p.m. UTC 
In quirk_huawei_pcie_sva(), use device_create_managed_software_node()
instead of device_add_properties() to set the "dma-can-stall"
property.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
Hi,

The commit message now says what Bjorn requested, except I left out
the claim that the patch fixes a lifetime issue.

There shouldn't be any functional impact.

thanks,
---
 drivers/pci/quirks.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Bjorn Helgaas Sept. 30, 2021, 3:04 p.m. UTC | #1 
On Thu, Sep 30, 2021 at 03:12:45PM +0300, Heikki Krogerus wrote:
> In quirk_huawei_pcie_sva(), use device_create_managed_software_node()
> instead of device_add_properties() to set the "dma-can-stall"
> property.
> 
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Acked-by: Zhangfei Gao <zhangfei.gao@linaro.org>
> Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> ---
> Hi,
> 
> The commit message now says what Bjorn requested, except I left out
> the claim that the patch fixes a lifetime issue.

Thanks.

The commit log should help reviewers determine whether the change is
safe and necessary.  So far it doesn't have any hints along that line.

Comparing device_add_properties() [1] and
device_create_managed_software_node() [2], the only difference in this
case is that the latter sets "swnode->managed = true".  The function
comment says "managed" means the lifetime of the swnode is tied to the
lifetime of dev, hence my question about a lifetime issue.

I can see that one reason for this change is to remove the last caller
of device_add_properties(), so device_add_properties() itself can be
removed.  That's a good reason for wanting to do it, and the commit
log could mention it.

But it doesn't help me figure out whether it's safe.  For that,
I need to know the effect of setting "managed = true".  Obviously
it means *something*, but I don't know what.  It looks like the only
test is in software_node_notify():

  device_del
    device_platform_notify_remove
      software_node_notify_remove
        sysfs_remove_link(dev_name)
        sysfs_remove_link("software_node")
        if (swnode->managed)                 <--
          set_secondary_fwnode(dev, NULL)
          kobject_put(&swnode->kobj)
    device_remove_properties
      if (is_software_node())
        fwnode_remove_software_node
          kobject_put(&swnode->kobj)
        set_secondary_fwnode(dev, NULL)

I'm not sure what's going on here; it looks like some redundancy with
multiple calls of kobject_put() and set_secondary_fwnode().  Maybe you
are in the process of removing device_remove_properties() as well as
device_add_properties()?

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/base/property.c?id=v5.14#n533
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/base/swnode.c?id=v5.14#n1083

> There shouldn't be any functional impact.
> 
> thanks,
> ---
>  drivers/pci/quirks.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index b6b4c803bdc94..fe5eedba47908 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -1850,7 +1850,7 @@ static void quirk_huawei_pcie_sva(struct pci_dev *pdev)
>  	 * can set it directly.
>  	 */
>  	if (!pdev->dev.of_node &&
> -	    device_add_properties(&pdev->dev, properties))
> +	    device_create_managed_software_node(&pdev->dev, properties, NULL))
>  		pci_warn(pdev, "could not add stall property");
>  }
>  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_HUAWEI, 0xa250, quirk_huawei_pcie_sva);
> -- 
> 2.33.0
>
Heikki Krogerus Oct. 1, 2021, 10:36 a.m. UTC | #2 
On Thu, Sep 30, 2021 at 10:04:02AM -0500, Bjorn Helgaas wrote:
> On Thu, Sep 30, 2021 at 03:12:45PM +0300, Heikki Krogerus wrote:
> > In quirk_huawei_pcie_sva(), use device_create_managed_software_node()
> > instead of device_add_properties() to set the "dma-can-stall"
> > property.
> > 
> > Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> > Acked-by: Zhangfei Gao <zhangfei.gao@linaro.org>
> > Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> > ---
> > Hi,
> > 
> > The commit message now says what Bjorn requested, except I left out
> > the claim that the patch fixes a lifetime issue.
> 
> Thanks.
> 
> The commit log should help reviewers determine whether the change is
> safe and necessary.  So far it doesn't have any hints along that line.
> 
> Comparing device_add_properties() [1] and
> device_create_managed_software_node() [2], the only difference in this
> case is that the latter sets "swnode->managed = true".  The function
> comment says "managed" means the lifetime of the swnode is tied to the
> lifetime of dev, hence my question about a lifetime issue.
> 
> I can see that one reason for this change is to remove the last caller
> of device_add_properties(), so device_add_properties() itself can be
> removed.  That's a good reason for wanting to do it, and the commit
> log could mention it.

Fair enough. I need to explain the why as well as the what.

I'll improve the commit message, but just to be clear, the goal is
actually not to get rid of device_add_properties(). It is removed in
the second patch together with device_remove_properties() because
there are simply no more users for that API.

> But it doesn't help me figure out whether it's safe.  For that,
> I need to know the effect of setting "managed = true".  Obviously
> it means *something*, but I don't know what.  It looks like the only
> test is in software_node_notify():
> 
>   device_del
>     device_platform_notify_remove
>       software_node_notify_remove
>         sysfs_remove_link(dev_name)
>         sysfs_remove_link("software_node")
>         if (swnode->managed)                 <--
>           set_secondary_fwnode(dev, NULL)
>           kobject_put(&swnode->kobj)
>     device_remove_properties
>       if (is_software_node())
>         fwnode_remove_software_node
>           kobject_put(&swnode->kobj)
>         set_secondary_fwnode(dev, NULL)
> 
> I'm not sure what's going on here; it looks like some redundancy with
> multiple calls of kobject_put() and set_secondary_fwnode().  Maybe you
> are in the process of removing device_remove_properties() as well as
> device_add_properties()?

It'll get removed, but that's not the goal. The goal is to get rid of
the call to it in device_del(), so not the function itself. That call
is the problem here as explained in commit 151f6ff78cdf ("software
node: Provide replacement for device_add_properties()").

I'll split the second patch, and first only remove that
device_remove_properties() call from device_del(), and only after
that remove the functions themselves.

thanks,
Rafael J. Wysocki Oct. 5, 2021, 2:04 p.m. UTC | #3 
On Fri, Oct 1, 2021 at 12:36 PM Heikki Krogerus
<heikki.krogerus@linux.intel.com> wrote:
>
> On Thu, Sep 30, 2021 at 10:04:02AM -0500, Bjorn Helgaas wrote:
> > On Thu, Sep 30, 2021 at 03:12:45PM +0300, Heikki Krogerus wrote:
> > > In quirk_huawei_pcie_sva(), use device_create_managed_software_node()
> > > instead of device_add_properties() to set the "dma-can-stall"
> > > property.
> > >
> > > Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> > > Acked-by: Zhangfei Gao <zhangfei.gao@linaro.org>
> > > Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> > > ---
> > > Hi,
> > >
> > > The commit message now says what Bjorn requested, except I left out
> > > the claim that the patch fixes a lifetime issue.
> >
> > Thanks.
> >
> > The commit log should help reviewers determine whether the change is
> > safe and necessary.  So far it doesn't have any hints along that line.
> >
> > Comparing device_add_properties() [1] and
> > device_create_managed_software_node() [2], the only difference in this
> > case is that the latter sets "swnode->managed = true".  The function
> > comment says "managed" means the lifetime of the swnode is tied to the
> > lifetime of dev, hence my question about a lifetime issue.
> >
> > I can see that one reason for this change is to remove the last caller
> > of device_add_properties(), so device_add_properties() itself can be
> > removed.  That's a good reason for wanting to do it, and the commit
> > log could mention it.
>
> Fair enough. I need to explain the why as well as the what.
>
> I'll improve the commit message, but just to be clear, the goal is
> actually not to get rid of device_add_properties(). It is removed in
> the second patch together with device_remove_properties() because
> there are simply no more users for that API.
>
> > But it doesn't help me figure out whether it's safe.  For that,
> > I need to know the effect of setting "managed = true".  Obviously
> > it means *something*, but I don't know what.  It looks like the only
> > test is in software_node_notify():
> >
> >   device_del
> >     device_platform_notify_remove
> >       software_node_notify_remove
> >         sysfs_remove_link(dev_name)
> >         sysfs_remove_link("software_node")
> >         if (swnode->managed)                 <--
> >           set_secondary_fwnode(dev, NULL)
> >           kobject_put(&swnode->kobj)
> >     device_remove_properties
> >       if (is_software_node())
> >         fwnode_remove_software_node
> >           kobject_put(&swnode->kobj)
> >         set_secondary_fwnode(dev, NULL)
> >
> > I'm not sure what's going on here; it looks like some redundancy with
> > multiple calls of kobject_put() and set_secondary_fwnode().  Maybe you
> > are in the process of removing device_remove_properties() as well as
> > device_add_properties()?
>
> It'll get removed, but that's not the goal. The goal is to get rid of
> the call to it in device_del(), so not the function itself. That call
> is the problem here as explained in commit 151f6ff78cdf ("software
> node: Provide replacement for device_add_properties()").
>
> I'll split the second patch, and first only remove that
> device_remove_properties() call from device_del(), and only after
> that remove the functions themselves.

So I'm expecting a v3 of this.
Heikki Krogerus Oct. 6, 2021, 9:48 a.m. UTC | #4 
On Tue, Oct 05, 2021 at 04:04:48PM +0200, Rafael J. Wysocki wrote:
> So I'm expecting a v3 of this.

Yes, sorry for the delay. v3 coming up.

thanks,
diff mbox series

Patch

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index b6b4c803bdc94..fe5eedba47908 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -1850,7 +1850,7 @@  static void quirk_huawei_pcie_sva(struct pci_dev *pdev)
 	 * can set it directly.
 	 */
 	if (!pdev->dev.of_node &&
-	    device_add_properties(&pdev->dev, properties))
+	    device_create_managed_software_node(&pdev->dev, properties, NULL))
 		pci_warn(pdev, "could not add stall property");
 }
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_HUAWEI, 0xa250, quirk_huawei_pcie_sva);