[Xen-devel] [PATCH] xen: debugging aid to track those who have disabled preemption

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1295273570 0
# Node ID 15e53a2463f084c3adbbb21b4deb30d0d4f79b45
# Parent  711cbaa038cae8c03cf825165d2e07b0a3c94f89
xen: debugging aid to track those who have disabled preemption.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

diff -r 711cbaa038ca -r 15e53a2463f0 xen/common/preempt.c
--- a/xen/common/preempt.c      Mon Jan 17 14:12:48 2011 +0000
+++ b/xen/common/preempt.c      Mon Jan 17 14:12:50 2011 +0000
@@ -21,5 +21,48 @@
  */
 
 #include <xen/preempt.h>
+#include <xen/symbols.h>
 
 DEFINE_PER_CPU(unsigned int, __preempt_count);
+
+#ifdef DEBUG_PREEMPT
+
+#define NR_PREEMPT_DEBUG 16
+
+struct preempt_info {
+       const char *file;
+       unsigned long line;
+       const char *func;
+       unsigned long r0, r1;
+};
+typedef struct preempt_info preempt_info_t[NR_PREEMPT_DEBUG];
+
+DEFINE_PER_CPU(preempt_info_t, __preempt_debug);
+
+void preempt_debug(const char *file, const unsigned long line, const char 
*func)
+{
+       struct preempt_info *pi = &this_cpu(__preempt_debug)[preempt_count()];
+       if (preempt_count() >= NR_PREEMPT_DEBUG)
+               return;
+       pi->file = file;
+       pi->func = func;
+       pi->line = line;
+       pi->r0 = (unsigned long)__builtin_return_address(0);
+       pi->r1 = (unsigned long)__builtin_return_address(1);
+}
+
+void preempt_debug_dump(void)
+{
+       struct preempt_info *pi = this_cpu(__preempt_debug);
+       int i, count = preempt_count();
+
+       printk("preempt debug on CPU%d, count %d:\n", smp_processor_id(), 
count);
+       count = min(count, NR_PREEMPT_DEBUG);
+       for(i=0;i<count;i++, pi++) {
+               printk("%d @ 0x%p\n", i, pi);
+               printk("  %s %s:%ld\n", pi->func, pi->file, pi->line);
+               printk("  %#lx", pi->r0); print_symbol(" %s\n", pi->r0);
+               printk("  %#lx", pi->r1); print_symbol(" %s\n", pi->r1);
+       }
+}
+#endif
diff -r 711cbaa038ca -r 15e53a2463f0 xen/drivers/char/console.c
--- a/xen/drivers/char/console.c        Mon Jan 17 14:12:48 2011 +0000
+++ b/xen/drivers/char/console.c        Mon Jan 17 14:12:50 2011 +0000
@@ -961,6 +961,7 @@ void panic(const char *fmt, ...)
     printk("Panic on CPU %d:\n", smp_processor_id());
     printk("%s", buf);
     printk("****************************************\n\n");
+    preempt_debug_dump();
     if ( opt_noreboot )
         printk("Manual reset required ('noreboot' specified)\n");
     else
diff -r 711cbaa038ca -r 15e53a2463f0 xen/include/xen/preempt.h
--- a/xen/include/xen/preempt.h Mon Jan 17 14:12:48 2011 +0000
+++ b/xen/include/xen/preempt.h Mon Jan 17 14:12:50 2011 +0000
@@ -18,7 +18,18 @@ DECLARE_PER_CPU(unsigned int, __preempt_
 
 #define preempt_count() (this_cpu(__preempt_count))
 
+//#define DEBUG_PREEMPT
+
+#ifdef DEBUG_PREEMPT
+extern void preempt_debug(const char *file, const unsigned long line, const 
char *func);
+extern void preempt_debug_dump(void);
+#else
+static inline void preempt_debug(const char *file, const unsigned long line, 
const char *func) {}
+static inline void preempt_debug_dump(void) {}
+#endif
+
 #define preempt_disable() do {                  \
+    preempt_debug(__FILE__, __LINE__, __func__);\
     preempt_count()++;                          \
     barrier();                                  \
 } while (0)

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel