On Wed, Sep 26, 2018 at 11:24:55AM -0700, Bart Van Assche wrote:
> On Wed, 2018-09-26 at 17:06 +0200, Johannes Thumshirn wrote:
> > On Wed, Sep 26, 2018 at 04:57:32PM +0200, Christoph Hellwig wrote:
> > > I don't think this actually works given that rpm_status only exists
> > > if CONFIG_PM is set.
> >
> > I think it'll work as GCC does constant propagation. There are
> > actually some places in the kernel that follow this pattern.
>
> This is what gcc on my development system thinks about that proposal:
>
> In file included from ./arch/x86/include/asm/bug.h:83:0,
> from ./include/linux/bug.h:5,
> from ./include/linux/thread_info.h:12,
> from ./arch/x86/include/asm/preempt.h:7,
> from ./include/linux/preempt.h:81,
> from ./include/linux/spinlock.h:51,
> from ./include/linux/seqlock.h:36,
> from ./include/linux/time.h:6,
> from ./include/linux/stat.h:19,
> from ./include/linux/module.h:10,
> from block/blk-core.c:15:
> block/blk-core.c: In function ‘elv_next_request’:
> block/blk-core.c:2795:44: error: ‘struct request_queue’ has no member named
> ‘rpm_status’; did you mean ‘stats’?
> WARN_ON_ONCE(q->rpm_status == RPM_SUSPENDED);
> ^
> ./include/asm-generic/bug.h:69:25: note: in definition of macro ‘WARN_ON_ONCE’
> int __ret_warn_on = !!(condition); \
> ^~~~~~~~~
> scripts/Makefile.build:305: recipe for target 'block/blk-core.o' failed
Aparently this only works for functions and not struct members, my
bad.
Johannes
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