On Mon, 3 Jun 2019 13:37:45 +0200 Cornelia Huck <cohuck@xxxxxxxxxx> wrote: > On Wed, 29 May 2019 14:26:51 +0200 > Michael Mueller <mimu@xxxxxxxxxxxxx> wrote: > > > From: Halil Pasic <pasic@xxxxxxxxxxxxx> > > > > To support protected virtualization cio will need to make sure the > > memory used for communication with the hypervisor is DMA memory. > > > > Let us introduce one global pool for cio. > > > > Our DMA pools are implemented as a gen_pool backed with DMA pages. The > > idea is to avoid each allocation effectively wasting a page, as we > > typically allocate much less than PAGE_SIZE. > > > > Signed-off-by: Halil Pasic <pasic@xxxxxxxxxxxxx> > > Reviewed-by: Sebastian Ott <sebott@xxxxxxxxxxxxx> > > Signed-off-by: Michael Mueller <mimu@xxxxxxxxxxxxx> > > --- > > arch/s390/Kconfig | 1 + > > arch/s390/include/asm/cio.h | 11 ++++ > > drivers/s390/cio/css.c | 120 ++++++++++++++++++++++++++++++++++++++++++-- > > 3 files changed, 128 insertions(+), 4 deletions(-) > > (...) > > > diff --git a/arch/s390/include/asm/cio.h b/arch/s390/include/asm/cio.h > > index 1727180e8ca1..43c007d2775a 100644 > > --- a/arch/s390/include/asm/cio.h > > +++ b/arch/s390/include/asm/cio.h > > @@ -328,6 +328,17 @@ static inline u8 pathmask_to_pos(u8 mask) > > void channel_subsystem_reinit(void); > > extern void css_schedule_reprobe(void); > > > > +extern void *cio_dma_zalloc(size_t size); > > +extern void cio_dma_free(void *cpu_addr, size_t size); > > +extern struct device *cio_get_dma_css_dev(void); > > + > > +struct gen_pool; > > That forward declaration is a bit ugly... Can you explain to me what is ugly about it so I can avoid similar mistakes in the future? >I guess the alternative was > include hell? > What do you mean by include hell? I decided to use a forward declaration because the guys that include "cio.h" are not expected to require the interfaces defined in linux/genalloc.h. My motivation to do it like this was the principle of encapsulation. Regards, Halil
