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    SubjectRe: [Xen-devel] [PATCH 03/11] Xen: Rename the balloon lock
    Hi. Please please don't move the arch common variable
    into x86 specific file. It causes link error on ia64.

    Before I sent the patches to fix it twice or so,
    but it seems to be dropped.


    On Thu, May 07, 2009 at 02:45:29PM -0700, Jeremy Fitzhardinge wrote:
    > From: Alex Nixon <alex.nixon@citrix.com>
    >
    > Impact: cleanup
    >
    > * xen_create_contiguous_region needs access to the balloon lock to
    > ensure memory doesn't change under its feet, so expose the balloon
    > lock
    > * Change the name of the lock to xen_reservation_lock, to imply it's
    > now less-specific usage.
    >
    > Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
    > Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
    > ---
    > arch/x86/xen/mmu.c | 7 +++++++
    > drivers/xen/balloon.c | 15 ++++-----------
    > include/xen/interface/memory.h | 8 ++++++++
    > 3 files changed, 19 insertions(+), 11 deletions(-)
    >
    > diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
    > index d673b03..218cf79 100644
    > --- a/arch/x86/xen/mmu.c
    > +++ b/arch/x86/xen/mmu.c
    > @@ -67,6 +67,13 @@
    >
    > #define MMU_UPDATE_HISTO 30
    >
    > +/*
    > + * Protects atomic reservation decrease/increase against concurrent increases.
    > + * Also protects non-atomic updates of current_pages and driver_pages, and
    > + * balloon lists.
    > + */
    > +DEFINE_SPINLOCK(xen_reservation_lock);
    > +
    > #ifdef CONFIG_XEN_DEBUG_FS
    >
    > static struct {
    > diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
    > index efa4b36..1e7984d 100644
    > --- a/drivers/xen/balloon.c
    > +++ b/drivers/xen/balloon.c
    > @@ -84,13 +84,6 @@ static struct sys_device balloon_sysdev;
    >
    > static int register_balloon(struct sys_device *sysdev);
    >
    > -/*
    > - * Protects atomic reservation decrease/increase against concurrent increases.
    > - * Also protects non-atomic updates of current_pages and driver_pages, and
    > - * balloon lists.
    > - */
    > -static DEFINE_SPINLOCK(balloon_lock);
    > -
    > static struct balloon_stats balloon_stats;
    >
    > /* We increase/decrease in batches which fit in a page */
    > @@ -209,7 +202,7 @@ static int increase_reservation(unsigned long nr_pages)
    > if (nr_pages > ARRAY_SIZE(frame_list))
    > nr_pages = ARRAY_SIZE(frame_list);
    >
    > - spin_lock_irqsave(&balloon_lock, flags);
    > + spin_lock_irqsave(&xen_reservation_lock, flags);
    >
    > page = balloon_first_page();
    > for (i = 0; i < nr_pages; i++) {
    > @@ -267,7 +260,7 @@ static int increase_reservation(unsigned long nr_pages)
    > totalram_pages = balloon_stats.current_pages;
    >
    > out:
    > - spin_unlock_irqrestore(&balloon_lock, flags);
    > + spin_unlock_irqrestore(&xen_reservation_lock, flags);
    >
    > return 0;
    > }
    > @@ -312,7 +305,7 @@ static int decrease_reservation(unsigned long nr_pages)
    > kmap_flush_unused();
    > flush_tlb_all();
    >
    > - spin_lock_irqsave(&balloon_lock, flags);
    > + spin_lock_irqsave(&xen_reservation_lock, flags);
    >
    > /* No more mappings: invalidate P2M and add to balloon. */
    > for (i = 0; i < nr_pages; i++) {
    > @@ -329,7 +322,7 @@ static int decrease_reservation(unsigned long nr_pages)
    > balloon_stats.current_pages -= nr_pages;
    > totalram_pages = balloon_stats.current_pages;
    >
    > - spin_unlock_irqrestore(&balloon_lock, flags);
    > + spin_unlock_irqrestore(&xen_reservation_lock, flags);
    >
    > return need_sleep;
    > }
    > diff --git a/include/xen/interface/memory.h b/include/xen/interface/memory.h
    > index f548f7c..9df4bd0 100644
    > --- a/include/xen/interface/memory.h
    > +++ b/include/xen/interface/memory.h
    > @@ -9,6 +9,8 @@
    > #ifndef __XEN_PUBLIC_MEMORY_H__
    > #define __XEN_PUBLIC_MEMORY_H__
    >
    > +#include <linux/spinlock.h>
    > +
    > /*
    > * Increase or decrease the specified domain's memory reservation. Returns a
    > * -ve errcode on failure, or the # extents successfully allocated or freed.
    > @@ -184,4 +186,10 @@ DEFINE_GUEST_HANDLE_STRUCT(xen_memory_map);
    > */
    > #define XENMEM_machine_memory_map 10
    >
    > +/*
    > + * Prevent the balloon driver from changing the memory reservation during a driver
    > + * critical region.
    > + */
    > +extern spinlock_t xen_reservation_lock;
    > +
    > #endif /* __XEN_PUBLIC_MEMORY_H__ */

    --
    yamahata


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