linux-kernel - Re: [1/1] powerpc/iommu: Handling null return of kzalloc

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Date:	Fri, 30 Jan 2015 13:17:36 +1100 (AEDT)
From:	Michael Ellerman <mpe@...erman.id.au>
To:	Zhouyi Zhou <zhouzhouyi@...il.com>, <benh@...nel.crashing.org>,
	<paulus@...ba.org>, <aik@...abs.ru>, <anton@...ba.org>,
	<nacc@...ux.vnet.ibm.com>, <alistair@...ple.id.au>,
	<deepthi@...ux.vnet.ibm.com>, <linuxppc-dev@...ts.ozlabs.org>,
	<linux-kernel@...r.kernel.org>
Cc:	Zhouyi Zhou <zhouzhouyi@...il.com>,
	Zhouyi Zhou <yizhouzhou@....ac.cn>
Subject: Re: [1/1] powerpc/iommu: Handling null return of kzalloc_node

On Tue, 2014-10-06 at 07:32:10 UTC, Zhouyi Zhou wrote:
> NULL return of kzalloc_node should be handled 

Yeah it should.

But just returning doesn't seem like it's going to end well. We end up with a
device that's not properly setup.

I think we need to rework that further so that either the error is propagated
up the stack, or the device is left in a working but degraded state.

cheers


 
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 33b552f..593cd3d 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -613,7 +613,11 @@ static void pci_dma_bus_setup_pSeries(struct pci_bus *bus)
>  
>  	tbl = kzalloc_node(sizeof(struct iommu_table), GFP_KERNEL,
>  			   pci->phb->node);
> -
> +	if (!tbl) {
> +		pr_debug(" out of memory, can't create iommu_table !\n");
> +		return;
> +	}
> +
>  	iommu_table_setparms(pci->phb, dn, tbl);
>  	pci->iommu_table = iommu_init_table(tbl, pci->phb->node);
>  	iommu_register_group(tbl, pci_domain_nr(bus), 0);
> @@ -659,6 +663,10 @@ static void pci_dma_bus_setup_pSeriesLP(struct pci_bus *bus)
>  	if (!ppci->iommu_table) {
>  		tbl = kzalloc_node(sizeof(struct iommu_table), GFP_KERNEL,
>  				   ppci->phb->node);
> +		if (!tbl) {
> +			pr_debug(" out of memory, can't create iommu_table !\n");
> +			return;
> +		}
>  		iommu_table_setparms_lpar(ppci->phb, pdn, tbl, dma_window);
>  		ppci->iommu_table = iommu_init_table(tbl, ppci->phb->node);
>  		iommu_register_group(tbl, pci_domain_nr(bus), 0);
> @@ -686,6 +694,11 @@ static void pci_dma_dev_setup_pSeries(struct pci_dev *dev)
>  		pr_debug(" --> first child, no bridge. Allocating iommu table.\n");
>  		tbl = kzalloc_node(sizeof(struct iommu_table), GFP_KERNEL,
>  				   phb->node);
> +		if (!tbl) {
> +			pr_debug(" out of memory, can't create iommu_table !\n");
> +			return;
> +		}
> +
>  		iommu_table_setparms(phb, dn, tbl);
>  		PCI_DN(dn)->iommu_table = iommu_init_table(tbl, phb->node);
>  		iommu_register_group(tbl, pci_domain_nr(phb->bus), 0);
> @@ -1102,6 +1116,10 @@ static void pci_dma_dev_setup_pSeriesLP(struct pci_dev *dev)
>  	if (!pci->iommu_table) {
>  		tbl = kzalloc_node(sizeof(struct iommu_table), GFP_KERNEL,
>  				   pci->phb->node);
> +		if (!tbl) {
> +			pr_debug(" out of memory, can't create iommu_table !\n");
> +			return;
> +		}
>  		iommu_table_setparms_lpar(pci->phb, pdn, tbl, dma_window);
>  		pci->iommu_table = iommu_init_table(tbl, pci->phb->node);
>  		iommu_register_group(tbl, pci_domain_nr(pci->phb->bus), 0);
--
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