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    [W:0.025 / U:0.188 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site