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

Alexey Kardashevskiy
2020-08-24T05:07:18Z

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