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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>
 <952fb640-01dd-003f-7fcb-bd48446d526c@ozlabs.ru>
 <06f732abbc3e6d4745428c4fc8cc98baf960a2e0.camel@gmail.com>
From:   Alexey Kardashevskiy <aik@ozlabs.ru>
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Message-ID: <1a469384-91ad-81f0-2a42-4c985cbc92da@ozlabs.ru>
Date:   Mon, 31 Aug 2020 14:34:57 +1000
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On 29/08/2020 01:25, Leonardo Bras wrote:
> On Mon, 2020-08-24 at 15:07 +1000, Alexey Kardashevskiy wrote:
>>
>> 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?
> 
> I think it reads better, like "create a ddw property with this name".

This reads as "there are at least two ddw properties".

> Also, it makes possible to create ddw properties with other names, in
> case we decide to create properties with different names depending on
> the window created.

It is one window at any given moment, why call it different names... I
get the part that it is not always "direct" anymore but still...


> Also, it's probably optimized / inlined at this point.
> Is it ok doing it like this?
> 
>>
>>> +			       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.
> 
> Yeah, I had that question too. 
> Previous code was like that, and I as trying not to mess too much on
> how it's done.
> 
>>> +	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.
> 
> I agree. It's better if this function have it's own cleaning routine.
> It will be fixed for next version.
> 
>>
>>
>>> +
>>> +	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)"
> 
> It was previously like that, and all query_ddw() checks return value
> this way.

ah I see.

> Should I update them all or just this one?

Pick one variant and make sure all new lines use just that. In this
patch you add both variants. Thanks,

> 
> Thanks!
> 
>>
>>
>>>  		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