1 files changed, 12 insertions, 17 deletions
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 1f3152ad7213..dab356e3ff87 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -1829,30 +1829,28 @@ void hcall_tracepoint_unregfunc(void)
 #endif
 
 /*
- * 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.
+ * Keep track of hcall tracing depth and prevent recursion. Warn if any is
+ * detected because it may indicate a problem. This will not catch all
+ * problems with tracing code making hcalls, because the tracing might have
+ * been invoked from a non-hcall, so the first hcall could recurse into it
+ * without warning here, but this better than nothing.
+ *
+ * Hcalls with specific problems being traced should use the _notrace
+ * plpar_hcall variants.
  */
 static DEFINE_PER_CPU(unsigned int, hcall_trace_depth);
 
 
-void __trace_hcall_entry(unsigned long opcode, unsigned long *args)
+notrace void __trace_hcall_entry(unsigned long opcode, unsigned long *args)
 {
 	unsigned long flags;
 	unsigned int *depth;
 
-	/*
-	 * We cannot call tracepoints inside RCU idle regions which
-	 * means we must not trace H_CEDE.
-	 */
-	if (opcode == H_CEDE)
-		return;
-
 	local_irq_save(flags);
 
 	depth = this_cpu_ptr(&hcall_trace_depth);
 
-	if (*depth)
+	if (WARN_ON_ONCE(*depth))
 		goto out;
 
 	(*depth)++;
@@ -1864,19 +1862,16 @@ out:
 	local_irq_restore(flags);
 }
 
-void __trace_hcall_exit(long opcode, long retval, unsigned long *retbuf)
+notrace void __trace_hcall_exit(long opcode, long retval, unsigned long *retbuf)
 {
 	unsigned long flags;
 	unsigned int *depth;
 
-	if (opcode == H_CEDE)
-		return;
-
 	local_irq_save(flags);
 
 	depth = this_cpu_ptr(&hcall_trace_depth);
 
-	if (*depth)
+	if (*depth) /* Don't warn again on the way out */
 		goto out;
 
 	(*depth)++;