Re: [RFC/PATCH] Per-device parameter support (13/16)

From: Rusty Russell (rusty_at_rustcorp.com.au)
Date: 10/25/04

  • Next message: Jeff Garzik: "Re: Concerns about our pci_{save,restore}_state()" 
    To: Tejun Heo <tj@home-tj.org>
Date:	Mon, 25 Oct 2004 16:08:10 +1000

    On Sat, 2004-10-23 at 13:31 +0900, Tejun Heo wrote:
    > +/* For some reason, gcc aligns structures which contain other
    > + structures to 32-byte boundary even when __alignof__() the strucure
    > + is smaller than that. As we're gonna assemble paramset array
    > + manually, we need to set alignment explicitly. Also, we put all
    > + paramset array elements into .data.1 to avoid intervening variables
    > + of different types (kparam_string, kparam_array for now). */

    You need __attribute__((aligned(sizeof(void *))): see moduleparam.h.
    The padding between structures is arch-dependent (x86-64 found out the
    hard way when we changed kernel_param previously). Not sure why you're
    using a separate section here anyway.

    > +/* Bit flag */
    > +#define __DEVICE_PARAM_FLAG(Name, Field, Flag, Dfl, Inv, Perm, Desc) \
    > + param_check_uint(__devparam_data(Name), \
    > + &(((__devparam_type *)0)->Field)); \
    > + static struct kparam_flag __devparam_data(__param_flag_##Name) \
    > + __devparam_extra_section = { 0, Flag, Inv }; \
    > + __DEVICE_PARAM_CALL_RANGED(Name, param_set_flag, param_get_flag,\
    > + &__devparam_data(__param_flag_##Name), \
    > + sizeof(struct kparam_flag), 1, 0, Dfl, 0, Perm, Desc, \
    > + offsetof(struct kparam_flag, pflags), \
    > + offsetof(__devparam_type, Field), -1, -1)
    > +
    > +#define DEVICE_PARAM_FLAG(Name, Field, Flag, Dfl, Perm, Desc) \
    > + __DEVICE_PARAM_FLAG(Name, Field, Flag, Dfl, 0, Perm, Desc)

    Haven't read closely, but why is FLAG special?

    I think your macros might be better off always having the range, which
    would reduce the number of functions.. I like including the description
    in the macros: that's an improvement.

    I always disliked the _NAMED versions (if it's a good name for users,
    it's usually a good name for the variable and vice versa), but you might
    want to consider always having it if that's the common case.

    Cheers,
    Rusty. 

    -- 
A bad analogy is like a leaky screwdriver -- Richard Braakman
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