Re: [Xen-devel] [PATCH v5 2/7] xen/arm: make process_memory_node a device_tree_node_func

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 13 Aug 2019, Julien Grall wrote:
> On 8/12/19 11:28 PM, Stefano Stabellini wrote:
> > Change the signature of process_memory_node to match
> > device_tree_node_func. Thanks to this change, the next patch will be
> > able to use device_tree_for_each_node to call process_memory_node on all
> > the children of a provided node.
> > 
> > Return error if there is no reg property or if nr_banks is reached. Let
> > the caller deal with the error.
> > 
> > Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
> > ---
> > Changes in v5:
> > - return -ENOENT if address_cells or size_cells are not properly set
> > 
> > Changes in v4:
> > - return error if there is no reg propery, remove printk
> > - return error if nr_banks is reached
> > 
> > Changes in v3:
> > - improve commit message
> > - check return value of process_memory_node
> > 
> > Changes in v2:
> > - new
> > ---
> >   xen/arch/arm/bootfdt.c | 29 +++++++++++++++--------------
> >   1 file changed, 15 insertions(+), 14 deletions(-)
> > 
> > diff --git a/xen/arch/arm/bootfdt.c b/xen/arch/arm/bootfdt.c
> > index a872ea57d6..590b14304c 100644
> > --- a/xen/arch/arm/bootfdt.c
> > +++ b/xen/arch/arm/bootfdt.c
> > @@ -125,9 +125,10 @@ int __init device_tree_for_each_node(const void *fdt,
> > int node,
> >       return 0;
> >   }
> >   -static void __init process_memory_node(const void *fdt, int node,
> > -                                       const char *name,
> > -                                       u32 address_cells, u32 size_cells)
> > +static int __init process_memory_node(const void *fdt, int node,
> > +                                      const char *name, int depth,
> > +                                      u32 address_cells, u32 size_cells,
> > +                                      void *data)
> >   {
> >       const struct fdt_property *prop;
> >       int i;
> > @@ -137,18 +138,11 @@ static void __init process_memory_node(const void
> > *fdt, int node,
> >       u32 reg_cells = address_cells + size_cells;
> >         if ( address_cells < 1 || size_cells < 1 )
> > -    {
> > -        printk("fdt: node `%s': invalid #address-cells or #size-cells",
> > -               name);
> > -        return;
> > -    }
> > +        return -ENOENT;
> 
> I saw your answer on the previous version and didn't get the chance. Missing
> the "regs" property and wrong {address,size}-cells values are two different
> things.
> 
> In the former case, it just means the reserved-region will be allocated
> dynamically.
> 
> In the latter case, this is an error in the device-tree configuration. If you
> ignore it, you are at risk to not take into account a reserved-region.
> 
> I agree this is a bug in the Device-Tree, but doing basic sanity check for the
> users is always helpful.
> 
> With that in mind, I would keep the printk and return a different error here.

OK. I'll use -EINVAL for this case, and keep the printk.

 
> >         prop = fdt_get_property(fdt, node, "reg", NULL);
> >       if ( !prop )
> > -    {
> > -        printk("fdt: node `%s': missing `reg' property\n", name);
> > -        return;
> > -    }
> > +        return -ENOENT;
> >         cell = (const __be32 *)prop->data;
> >       banks = fdt32_to_cpu(prop->len) / (reg_cells * sizeof (u32));
> > @@ -162,6 +156,10 @@ static void __init process_memory_node(const void *fdt,
> > int node,
> >           bootinfo.mem.bank[bootinfo.mem.nr_banks].size = size;
> >           bootinfo.mem.nr_banks++;
> >       }
> > +
> > +    if ( bootinfo.mem.nr_banks == NR_MEM_BANKS )
> > +        return -ENOSPC;
> > +    return 0;
> >   }
> >     static void __init process_multiboot_node(const void *fdt, int node,
> > @@ -293,15 +291,18 @@ static int __init early_scan_node(const void *fdt,
> >                                     u32 address_cells, u32 size_cells,
> >                                     void *data)
> >   {
> > +    int rc = 0;
> > +
> >       if ( device_tree_node_matches(fdt, node, "memory") )
> > -        process_memory_node(fdt, node, name, address_cells, size_cells);
> > +        rc = process_memory_node(fdt, node, name, depth,
> > +                                 address_cells, size_cells, NULL);
> 
> As a small NIT there are no way for the user to know that the parsing failed
> because of the reg property were missing. Could you print an error message
> either here or maybe in device_tree_for_each() to say parsing as failed for
> node N?

I'll add a new printk at the end of early_scan_node


> >       else if ( depth <= 3 && (device_tree_node_compatible(fdt, node,
> > "xen,multiboot-module" ) ||
> >                 device_tree_node_compatible(fdt, node, "multiboot,module"
> > )))
> >           process_multiboot_node(fdt, node, name, address_cells,
> > size_cells);
> >       else if ( depth == 1 && device_tree_node_matches(fdt, node, "chosen")
> > )
> >           process_chosen_node(fdt, node, name, address_cells, size_cells);
> >   -    return 0;
> > +    return rc;
> >   }
> >     static void __init early_print_info(void)

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