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SubjectRe: [Xen-devel] [PATCH 03/10] Xen: Rename the balloon lock
On Tue, May 12, 2009 at 02:48:04PM -0700, Jeremy Fitzhardinge wrote:
> From: Alex Nixon <alex.nixon@citrix.com>
>
> * 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.
>
> [Impact: cleanup ]
> 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(-)


Are you suggesting that ia64/xen should define its own
xen_reservation_lock?
Then, can you replace the patch with the following one?

The difference from the original is only the hunk in
arch/ia64/xen/hypervisor.c.
Although it is easy to fix it by ia64 specific patch, I prefer
not to break from the first place.

thanks,

--

From: Alex Nixon <alex.nixon@citrix.com>

* 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.

[Impact: cleanup ]
Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/ia64/xen/hypervisor.c | 7 +++++++
arch/x86/xen/mmu.c | 7 +++++++
drivers/xen/balloon.c | 15 ++++-----------
include/xen/interface/memory.h | 8 ++++++++
4 files changed, 26 insertions(+), 11 deletions(-)
diff --git a/arch/ia64/xen/hypervisor.c b/arch/ia64/xen/hypervisor.c
index cac4d97..481fbae 100644
--- a/arch/ia64/xen/hypervisor.c
+++ b/arch/ia64/xen/hypervisor.c
@@ -39,6 +39,13 @@ EXPORT_SYMBOL(xen_domain_type);

EXPORT_SYMBOL(__hypercall);

+/*
+ * 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);
+
/* Stolen from arch/x86/xen/enlighten.c */
/*
* Flag to determine whether vcpu info placement is available on all
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index e25a78e..360e546 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -65,6 +65,13 @@

#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 f5bbd9e..46a8b39 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 af36ead..29c2f58 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.
@@ -142,4 +144,10 @@ struct xen_translate_gpfn_list {
};
DEFINE_GUEST_HANDLE_STRUCT(xen_translate_gpfn_list);

+/*
+ * 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__ */
--
1.6.0.2



--
yamahata


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