linux-kernel - Re: [PATCH v6 04/18] powerpc/pseries: add of_node_put() in dlpar_detach

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Date:   Wed, 07 Nov 2018 23:23:27 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     frowand.list@...il.com, Rob Herring <robh+dt@...nel.org>,
        Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Alan Tull <atull@...nel.org>, Moritz Fischer <mdf@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        devicetree@...r.kernel.org, linux-fpga@...r.kernel.org
Subject: Re: [PATCH v6 04/18] powerpc/pseries: add of_node_put() in dlpar_detach_node()

frowand.list@...il.com writes:

> From: Frank Rowand <frank.rowand@...y.com>
>
> "of: overlay: add missing of_node_get() in __of_attach_node_sysfs"

It would be clearer if you said 'The previous commit "of: overlay ..."

> added a missing of_node_get() to __of_attach_node_sysfs().  This
> results in a refcount imbalance for nodes attached with
> dlpar_attach_node().  The calling sequence from dlpar_attach_node()
> to __of_attach_node_sysfs() is:
>
>    dlpar_attach_node()
>       of_attach_node()
>          __of_attach_node_sysfs()
>
> Tested-by: Alan Tull <atull@...nel.org>
> Signed-off-by: Frank Rowand <frank.rowand@...y.com>
> ---
>
> ***** UNTESTED.  I need people with the affected PowerPC systems
> *****            (systems that dynamically allocate and deallocate
> *****            devicetree nodes) to test this patch.

This looks OK to me in light of the previous patch.

Acked-by: Michael Ellerman <mpe@...erman.id.au>

It also means dlpar_detach_node() is again behaving as described in the
comment to of_detach_node().

It would be good to make mention of:

  Fixes: 68baf692c435 ("powerpc/pseries: Fix of_node_put() underflow during DLPAR remove")

Which removed an of_node_put() in the exact same place for different
reasons.

cheers

> diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
> index 7625546caefd..17958043e7f7 100644
> --- a/arch/powerpc/platforms/pseries/dlpar.c
> +++ b/arch/powerpc/platforms/pseries/dlpar.c
> @@ -270,6 +270,8 @@ int dlpar_detach_node(struct device_node *dn)
>  	if (rc)
>  		return rc;
>  
> +	of_node_put(dn);
> +
>  	return 0;
>  }
>  
> -- 
> Frank Rowand <frank.rowand@...y.com>