linux-kernel - Re: [PATCH AUTOSEL 5.4 70/78] pci/hotplug/pnv-php: Remove erroneous warning

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Date:   Tue, 21 Apr 2020 13:03:34 +0200
From:   Frederic Barrat <fbarrat@...ux.ibm.com>
To:     Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Cc:     "Alastair D'Silva" <alastair@...ilva.org>,
        Andrew Donnellan <ajd@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev@...ts.ozlabs.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 5.4 70/78] pci/hotplug/pnv-php: Remove erroneous
 warning



Le 18/04/2020 à 16:40, Sasha Levin a écrit :
> From: Frederic Barrat <fbarrat@...ux.ibm.com>
> 
> [ Upstream commit 658ab186dd22060408d94f5c5a6d02d809baba44 ]


This doesn't need to be backported to stable.

   Fred


> On powernv, when removing a device through hotplug, the following
> warning is logged:
> 
>       Invalid refcount <.> on <...>
> 
> It may be incorrect, the refcount may be set to a higher value than 1
> and be valid. of_detach_node() can drop more than one reference. As it
> doesn't seem trivial to assert the correct value, let's remove the
> warning.
> 
> Reviewed-by: Alastair D'Silva <alastair@...ilva.org>
> Reviewed-by: Andrew Donnellan <ajd@...ux.ibm.com>
> Signed-off-by: Frederic Barrat <fbarrat@...ux.ibm.com>
> Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
> Link: https://lore.kernel.org/r/20191121134918.7155-7-fbarrat@linux.ibm.com
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>   drivers/pci/hotplug/pnv_php.c | 6 ------
>   1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c
> index d7b2b47bc33eb..6037983c6e46b 100644
> --- a/drivers/pci/hotplug/pnv_php.c
> +++ b/drivers/pci/hotplug/pnv_php.c
> @@ -151,17 +151,11 @@ static void pnv_php_rmv_pdns(struct device_node *dn)
>   static void pnv_php_detach_device_nodes(struct device_node *parent)
>   {
>   	struct device_node *dn;
> -	int refcount;
>   
>   	for_each_child_of_node(parent, dn) {
>   		pnv_php_detach_device_nodes(dn);
>   
>   		of_node_put(dn);
> -		refcount = kref_read(&dn->kobj.kref);
> -		if (refcount != 1)
> -			pr_warn("Invalid refcount %d on <%pOF>\n",
> -				refcount, dn);
> -
>   		of_detach_node(dn);
>   	}
>   }
>