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    SubjectRe: [PATCH 15/25] autofs: move ioctl32 to autofs{,4}/root.c
    On Mon, 7 Nov 2005, Arnd Bergmann wrote:

    > On Sünndag 06 November 2005 07:22, Ian Kent wrote:
    > > On Sat, 5 Nov 2005, Arnd Bergmann wrote:
    > >
    > > I'm not sure if I like conditional compilation in the code proper but I'll
    > > leave it to you to make the final decision since your running with the
    > > change. Is there a reason the definitions can't simply be left in place?
    >
    > I think the compat_ptr() macro is not defined on architectures that don't
    > have 32 bit compat code, but we could change that.
    >
    > > Its been a while since I trawled through the compat ioctl code (please
    > > point me to the right place) but with this change I think that the
    > > AUTOFS_IOC_SETTIMEOUT32 is redundant. Consider a conditional define for
    > > AUTOFS_IOC_SETTIMEOUT in include/linux/auto_fs.h instead. Both autofs and
    > > autofs4 use that definition.
    >
    > The point here is that the two are different on 64 bit platforms, since
    > sizeof (int) != sizeof (long). You also can't do
    >
    > switch (cmd) {
    > case AUTOFS_IOC_SETTIMEOUT32:
    > case AUTOFS_IOC_SETTIMEOUT:
    > return do_stuff();
    > }
    >
    > because then gcc would complain about duplicate case targets on 32 bit
    > targets.

    I was thinking that if the module was compiled for 64bit then the 64bit
    definition would prevail and visa versa.

    eg. In the include file.

    #ifdef COMPAT_IOCTL
    #define AUTOFS_IOC_SETTIMEOUT(..., unsigned int)
    #else
    #define AUTOFS_IOC_SETTIMEOUT(...,unsigned long)
    #endif

    I think I'm going to have to investigate further following the
    implementation.

    >
    > > The lock_kernel()/unlock_kernel() in the autofs4 patch is ineffective as
    > > the BKL is not used for syncronisation anywhere else in autofs4. If
    > > removing it causes problems I need to know about'em so I can fix'em
    > > (hopefully).
    >
    > I used the BKL here in order to maintain the current semantics, because
    > ioctl is always called with BKL held, and compat_ioctl is called without
    > it.

    Of course a sensible approach.

    >
    > If you are sure you don't need the BKL, then you should also replace
    > ".ioctl = ..." with ".unlocked_ioctl = ...".

    Yep. I'll check and amend it later.
    After all it will be part of the module then.

    Thanks
    Ian
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