From 07fdbd0ab01b821f362d9b5bfe0cfba675255328 Mon Sep 17 00:00:00 2001
From: Anton Blanchard <anton@samba.org>
Date: Thu, 21 Oct 2010 00:52:12 +0000
Subject: [PATCH] --- yaml --- r: 232977 b: refs/heads/master c:
 57cdfdf829a850a317425ed93c6a576c9ee6329c h: refs/heads/master i:   232975:
 c80321a493e035114c5aa63678500c7ebecf7e0a v: v3

---
 [refs]                                      |  2 +-
 trunk/arch/powerpc/platforms/pseries/lpar.c | 37 +++++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 02e63ee4a490..743d4dece6b0 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 429f4d8d20b91e4a6c239f951c06a56a6ac22957
+refs/heads/master: 57cdfdf829a850a317425ed93c6a576c9ee6329c
diff --git a/trunk/arch/powerpc/platforms/pseries/lpar.c b/trunk/arch/powerpc/platforms/pseries/lpar.c
index 5d3ea9f60dd7..ca5d5898d320 100644
--- a/trunk/arch/powerpc/platforms/pseries/lpar.c
+++ b/trunk/arch/powerpc/platforms/pseries/lpar.c
@@ -713,6 +713,13 @@ EXPORT_SYMBOL(arch_free_page);
 /* NB: reg/unreg are called while guarded with the tracepoints_mutex */
 extern long hcall_tracepoint_refcount;
 
+/* 
+ * Since the tracing code might execute hcalls we need to guard against
+ * recursion. One example of this are spinlocks calling H_YIELD on
+ * shared processor partitions.
+ */
+static DEFINE_PER_CPU(unsigned int, hcall_trace_depth);
+
 void hcall_tracepoint_regfunc(void)
 {
 	hcall_tracepoint_refcount++;
@@ -725,12 +732,42 @@ void hcall_tracepoint_unregfunc(void)
 
 void __trace_hcall_entry(unsigned long opcode, unsigned long *args)
 {
+	unsigned long flags;
+	unsigned int *depth;
+
+	local_irq_save(flags);
+
+	depth = &__get_cpu_var(hcall_trace_depth);
+
+	if (*depth)
+		goto out;
+
+	(*depth)++;
 	trace_hcall_entry(opcode, args);
+	(*depth)--;
+
+out:
+	local_irq_restore(flags);
 }
 
 void __trace_hcall_exit(long opcode, unsigned long retval,
 			unsigned long *retbuf)
 {
+	unsigned long flags;
+	unsigned int *depth;
+
+	local_irq_save(flags);
+
+	depth = &__get_cpu_var(hcall_trace_depth);
+
+	if (*depth)
+		goto out;
+
+	(*depth)++;
 	trace_hcall_exit(opcode, retval, retbuf);
+	(*depth)--;
+
+out:
+	local_irq_restore(flags);
 }
 #endif