lkml.org 
[lkml]   [2011]   [Oct]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: gpio-ml-ioh: Support interrupt function
On Tue, 18 Oct 2011, Tomoya MORINAGA wrote:

> > The linux-next patch 54be566317b6 "gpio-ml-ioh: Support interrupt
> > function" generates a Sparse warning.
> >
> > + irq_base = irq_alloc_descs(-1, IOH_IRQ_BASE, num_ports[j],
> > + GFP_KERNEL);
> > ^^^^^^^^^^
> >
> > The last argument should be a NUMA node, not a GFP_ flag. I'm not
> > sure what the right fix is. There are currently 5 callers in my
> > cscope for this function in linux-next.
> >
> > 2 pass GFP_KERNEL which is wrong.

Right, all irq_alloc_descs() allocations are already implicitly
GFP_KERNEL.

> > 2 pass 0 which maybe should be cpu_to_node(0)?
> > 1 passes -1 which maybe could be NUMA_NO_NODE?
> >
> I can understand your saying.
> Seeing accepted other drivers, '0' or '-1' is used.

There's actually no guarantee in the kernel that node 0 has memory, so
unless that is assured in the context then passing 0 would be wrong.

> Focusing on GPIO driver, gpio-pca953x.c uses '-1'.
>

The slab layer guarantees that passing -1 will allocate on the node that
is local to the cpu that the code is running on. Unless there's a
compelling reason to allocate on a different node, then this is what you
want to use.

We try not to pass -1 directly, though, we try to use NUMA_NO_NODE
wherever possible.


\
 
 \ /
  Last update: 2011-10-18 07:59    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site