Re: [PATCH v1 08/10] powerpc/pseries/iommu: Add ddw_property_create() and refactor enable_ddw()

Alexey Kardashevskiy
2020-08-31T04:35:09Z

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