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Subject: Re: [PATCH v1 08/10] powerpc/pseries/iommu: Add ddw_property_create()
 and refactor enable_ddw()
To:     Leonardo Bras <leobras.c@gmail.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Christophe Leroy <christophe.leroy@c-s.fr>,
        Joel Stanley <joel@jms.id.au>,
        Thiago Jung Bauermann <bauerman@linux.ibm.com>,
        Ram Pai <linuxram@us.ibm.com>,
        Brian King <brking@linux.vnet.ibm.com>,
        Murilo Fossa Vicentini <muvic@linux.ibm.com>,
        David Dai <zdai@linux.vnet.ibm.com>
Cc:     linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
References: <20200817234033.442511-1-leobras.c@gmail.com>
 <20200817234033.442511-9-leobras.c@gmail.com>
From:   Alexey Kardashevskiy <aik@ozlabs.ru>
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Message-ID: <952fb640-01dd-003f-7fcb-bd48446d526c@ozlabs.ru>
Date:   Mon, 24 Aug 2020 15:07:04 +1000
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On 18/08/2020 09:40, Leonardo Bras wrote:
> Code used to create a ddw property that was previously scattered in
> enable_ddw() is now gathered in ddw_property_create(), which deals with
> allocation and filling the property, letting it ready for
> of_property_add(), which now occurs in sequence.
> 
> This created an opportunity to reorganize the second part of enable_ddw():
> 
> Without this patch enable_ddw() does, in order:
> kzalloc() property & members, create_ddw(), fill ddwprop inside property,
> ddw_list_add(), do tce_setrange_multi_pSeriesLP_walk in all memory,
> of_add_property().
> 
> With this patch enable_ddw() does, in order:
> create_ddw(), ddw_property_create(), of_add_property(), ddw_list_add(),
> do tce_setrange_multi_pSeriesLP_walk in all memory.
> 
> This change requires of_remove_property() in case anything fails after
> of_add_property(), but we get to do tce_setrange_multi_pSeriesLP_walk
> in all memory, which looks the most expensive operation, only if
> everything else succeeds.
> 
> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> ---
>  arch/powerpc/platforms/pseries/iommu.c | 97 +++++++++++++++-----------
>  1 file changed, 57 insertions(+), 40 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 4031127c9537..3a1ef02ad9d5 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -1123,6 +1123,31 @@ static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn)
>  			 ret);
>  }
>  
> +static int ddw_property_create(struct property **ddw_win, const char *propname,

@propname is always the same, do you really want to pass it every time?

> +			       u32 liobn, u64 dma_addr, u32 page_shift, u32 window_shift)
> +{
> +	struct dynamic_dma_window_prop *ddwprop;
> +	struct property *win64;
> +
> +	*ddw_win = win64 = kzalloc(sizeof(*win64), GFP_KERNEL);
> +	if (!win64)
> +		return -ENOMEM;
> +
> +	win64->name = kstrdup(propname, GFP_KERNEL);

Not clear why "win64->name = DIRECT64_PROPNAME" would not work here, the
generic OF code does not try kfree() it but it is probably out of scope
here.


> +	ddwprop = kzalloc(sizeof(*ddwprop), GFP_KERNEL);
> +	win64->value = ddwprop;
> +	win64->length = sizeof(*ddwprop);
> +	if (!win64->name || !win64->value)
> +		return -ENOMEM;


Up to 2 memory leaks here. I see the cleanup at "out_free_prop:" but
still looks fragile. Instead you could simply return win64 as the only
error possible here is -ENOMEM and returning NULL is equally good.


> +
> +	ddwprop->liobn = cpu_to_be32(liobn);
> +	ddwprop->dma_base = cpu_to_be64(dma_addr);
> +	ddwprop->tce_shift = cpu_to_be32(page_shift);
> +	ddwprop->window_shift = cpu_to_be32(window_shift);
> +
> +	return 0;
> +}
> +
>  /*
>   * If the PE supports dynamic dma windows, and there is space for a table
>   * that can map all pages in a linear offset, then setup such a table,
> @@ -1140,12 +1165,11 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  	struct ddw_query_response query;
>  	struct ddw_create_response create;
>  	int page_shift;
> -	u64 max_addr;
> +	u64 max_addr, win_addr;
>  	struct device_node *dn;
>  	u32 ddw_avail[DDW_APPLICABLE_SIZE];
>  	struct direct_window *window;
> -	struct property *win64;
> -	struct dynamic_dma_window_prop *ddwprop;
> +	struct property *win64 = NULL;
>  	struct failed_ddw_pdn *fpdn;
>  	bool default_win_removed = false;
>  
> @@ -1244,38 +1268,34 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  		goto out_failed;
>  	}
>  	len = order_base_2(max_addr);
> -	win64 = kzalloc(sizeof(struct property), GFP_KERNEL);
> -	if (!win64) {
> -		dev_info(&dev->dev,
> -			"couldn't allocate property for 64bit dma window\n");
> +
> +	ret = create_ddw(dev, ddw_avail, &create, page_shift, len);
> +	if (ret != 0)

It is usually just "if (ret)"


>  		goto out_failed;
> -	}
> -	win64->name = kstrdup(DIRECT64_PROPNAME, GFP_KERNEL);
> -	win64->value = ddwprop = kmalloc(sizeof(*ddwprop), GFP_KERNEL);
> -	win64->length = sizeof(*ddwprop);
> -	if (!win64->name || !win64->value) {
> +
> +	dev_dbg(&dev->dev, "created tce table LIOBN 0x%x for %pOF\n",
> +		create.liobn, dn);
> +
> +	win_addr = ((u64)create.addr_hi << 32) | create.addr_lo;
> +	ret = ddw_property_create(&win64, DIRECT64_PROPNAME, create.liobn, win_addr,
> +				  page_shift, len);
> +	if (ret) {
>  		dev_info(&dev->dev,
> -			"couldn't allocate property name and value\n");
> +			 "couldn't allocate property, property name, or value\n");
>  		goto out_free_prop;
>  	}
>  
> -	ret = create_ddw(dev, ddw_avail, &create, page_shift, len);
> -	if (ret != 0)
> +	ret = of_add_property(pdn, win64);
> +	if (ret) {
> +		dev_err(&dev->dev, "unable to add dma window property for %pOF: %d",
> +			pdn, ret);
>  		goto out_free_prop;
> -
> -	ddwprop->liobn = cpu_to_be32(create.liobn);
> -	ddwprop->dma_base = cpu_to_be64(((u64)create.addr_hi << 32) |
> -			create.addr_lo);
> -	ddwprop->tce_shift = cpu_to_be32(page_shift);
> -	ddwprop->window_shift = cpu_to_be32(len);
> -
> -	dev_dbg(&dev->dev, "created tce table LIOBN 0x%x for %pOF\n",
> -		  create.liobn, dn);
> +	}
>  
>  	/* Add new window to existing DDW list */
> -	window = ddw_list_add(pdn, ddwprop);
> +	window = ddw_list_add(pdn, win64->value);
>  	if (!window)
> -		goto out_clear_window;
> +		goto out_prop_del;
>  
>  	ret = walk_system_ram_range(0, memblock_end_of_DRAM() >> PAGE_SHIFT,
>  			win64->value, tce_setrange_multi_pSeriesLP_walk);
> @@ -1285,14 +1305,7 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  		goto out_free_window;
>  	}
>  
> -	ret = of_add_property(pdn, win64);
> -	if (ret) {
> -		dev_err(&dev->dev, "unable to add dma window property for %pOF: %d",
> -			 pdn, ret);
> -		goto out_free_window;
> -	}
> -
> -	dev->dev.archdata.dma_offset = be64_to_cpu(ddwprop->dma_base);
> +	dev->dev.archdata.dma_offset = win_addr;
>  	goto out_unlock;
>  
>  out_free_window:
> @@ -1302,14 +1315,18 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  
>  	kfree(window);
>  
> -out_clear_window:
> -	remove_ddw(pdn, true);
> +out_prop_del:
> +	of_remove_property(pdn, win64);
>  
>  out_free_prop:
> -	kfree(win64->name);
> -	kfree(win64->value);
> -	kfree(win64);
> -	win64 = NULL;
> +	if (win64) {
> +		kfree(win64->name);
> +		kfree(win64->value);
> +		kfree(win64);
> +		win64 = NULL;
> +	}
> +
> +	remove_ddw(pdn, true);
>  
>  out_failed:
>  	if (default_win_removed)
> 

-- 
Alexey