Re: [RFC/PATCH] PCI: Protect pci_reassign_bridge_resources() against concurrent addition/removal

[Bjorn Helgaas <helgaas@kernel.org>]

On Mon, Jun 24, 2019 at 02:32:19PM +1000, Benjamin Herrenschmidt wrote:
> pci_reassign_bridge_resources() can be called by pci_resize_resource()
> at runtime.
> 
> It will walk the PCI tree up and down, and isn't currently protected
> against any changes or hotplug operation.
> 
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Applied to pci/resource for v5.4, thanks!

> ---
> 
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -2104,6 +2104,8 @@ int pci_reassign_bridge_resources(struct pci_dev *bridge, unsigned long type)
>  	unsigned int i;
>  	int ret;
>  
> +	down_read(&pci_bus_sem);
> +
>  	/* Walk to the root hub, releasing bridge BARs when possible */
>  	next = bridge;
>  	do {
> @@ -2160,6 +2162,7 @@ int pci_reassign_bridge_resources(struct pci_dev *bridge, unsigned long type)
>  	}
>  
>  	free_list(&saved);
> +	up_read(&pci_bus_sem);
>  	return 0;
>  
>  cleanup:
> @@ -2188,6 +2191,7 @@ int pci_reassign_bridge_resources(struct pci_dev *bridge, unsigned long type)
>  		pci_setup_bridge(bridge->subordinate);
>  	}
>  	free_list(&saved);
> +	up_read(&pci_bus_sem);
>  
>  	return ret;
>  }
>