[Xen-changelog] [xen-unstable] xenpaging: print info when free request slots drop below 2

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxx>
# Date 1290781149 0
# Node ID 3bbb3969236c3064139d443257ca1bf471d38d58
# Parent  d622cf8c372e8fb513781d3bfdff67d4eaa96e2e
xenpaging: print info when free request slots drop below 2

Add debugging aid to free request slots in the ring buffer.
It should not happen that the ring gets full, print info anyway if it
happens.

Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
---
 xen/arch/x86/mm/mem_event.c |    5 +++++
 1 files changed, 5 insertions(+)

diff -r d622cf8c372e -r 3bbb3969236c xen/arch/x86/mm/mem_event.c
--- a/xen/arch/x86/mm/mem_event.c       Fri Nov 26 14:18:32 2010 +0000
+++ b/xen/arch/x86/mm/mem_event.c       Fri Nov 26 14:19:09 2010 +0000
@@ -152,6 +152,11 @@ int mem_event_check_ring(struct domain *
     mem_event_ring_lock(d);
 
     free_requests = RING_FREE_REQUESTS(&d->mem_event.front_ring);
+    if ( unlikely(free_requests < 2) )
+    {
+        gdprintk(XENLOG_INFO, "free request slots: %d\n", free_requests);
+        WARN_ON(free_requests == 0);
+    }
     ring_full = free_requests < MEM_EVENT_RING_THRESHOLD;
 
     if ( (curr->domain->domain_id == d->domain_id) && ring_full )

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