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    SubjectRe: [PATCH v1] x86/platform/intel-mid: Revert "Make 'bt_sfi_data' const"


    On Thu, 28 Dec 2017, Ingo Molnar wrote:

    >
    > * Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
    >
    > > On Thu, 2017-12-28 at 11:28 +0100, Ingo Molnar wrote:
    > > > * Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
    > > >
    > > > > The annoying static analyzer follow up patches make a pain rather
    > > > > then
    > > > > fixing issues.
    > > > >
    > > > > The one done by commit 276c87054751
    > > > >
    > > > > ("x86/platform/intel-mid: Make 'bt_sfi_data' const")
    > > > >
    > > > > made an obvious regression [BugLink] since the struct bt_sfi_data
    > > > > used
    > > > > as a temporary container for important data that is used to fill
    > > > > 'parent' and 'name' fields in struct platform_device_info.
    > > > >
    > > > > That's why revert the commit which had been apparently done w/o
    > > > > reading
    > > > > the code.
    > > > >
    > > > > BugLink: https://github.com/andy-shev/linux/issues/20
    > > > > Cc: Bhumika Goyal <bhumirks@gmail.com>
    > > > > Cc: julia.lawall@lip6.fr
    > > > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
    > > > > ---
    > > > > arch/x86/platform/intel-mid/device_libs/platform_bt.c | 2 +-
    > > > > 1 file changed, 1 insertion(+), 1 deletion(-)
    > > > >
    > > > > diff --git a/arch/x86/platform/intel-mid/device_libs/platform_bt.c
    > > > > b/arch/x86/platform/intel-mid/device_libs/platform_bt.c
    > > > > index dc036e511f48..5a0483e7bf66 100644
    > > > > --- a/arch/x86/platform/intel-mid/device_libs/platform_bt.c
    > > > > +++ b/arch/x86/platform/intel-mid/device_libs/platform_bt.c
    > > > > @@ -60,7 +60,7 @@ static int __init tng_bt_sfi_setup(struct
    > > > > bt_sfi_data *ddata)
    > > > > return 0;
    > > > > }
    > > > >
    > > > > -static const struct bt_sfi_data tng_bt_sfi_data __initdata = {
    > > > > +static struct bt_sfi_data tng_bt_sfi_data __initdata = {
    > > > > .setup = tng_bt_sfi_setup,
    > > > > };
    > > >
    > > > This is nasty, why didn't the compiler warn about this bug?
    > > >
    > > > Normally when using a const data structure for a non-const purpose.
    > > > (Unless
    > > > there's a type cast which loses the type - one of the many reasons why
    > > > type casts
    > > > should be avoided.)
    > >
    > > Now I'm trying to get this.
    > >
    > > First of all, the new dependency to hci_bcm makes this one not compiled
    > > at all.
    > >
    > > Second, there is a cast as you truthfully predicted...
    > >
    > > I would say that revert is needed, but it seems it wasn't a culprit for
    > > the bug (rather the new dependency is). So, it might need rewording of
    > > the commit message to low tone of the accusations.
    >
    > Your fix is absolutely needed and welcome, but I'd first like to see a build error
    > or build warning that avoids the introduction of this class of problems in the
    > future - then apply your fix in a separate patch.
    >
    > Constification patches are useful in general, and such breakages are hard to debug

    I will try to make the type adjustment. There does seem to be a few cases
    where the field actually does hold an integer. I guess this is not a
    problem?

    julia

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