- >500 static DTrace probes for the linuxulator

- DTrace scripts to check for errors, performance, ...
  they serve mostly as examples of what you can do with the static probe;s
  with moderate load the scripts may be overwhelmed, excessive lock-tracing
  may influence program behavior (see the last design decission)

Design decissions:
 - use "linuxulator" as the provider for the native bitsize; add the
   bitsize for the non-native emulation (e.g. "linuxuator32" on amd64)
 - Add probes only for locks which are acquired in one function and released
   in another function. Locks which are aquired and released in the same
   function should be easy to pair in the code, inter-function
   locking is more easy to verify in DTrace.
 - Probes for locks should be fired after locking and before releasing to
   prevent races (to provide data/function stability in DTrace, see the
   man-page of "dtrace -v ..." and the corresponding DTrace docs).

1 files changed, 36 insertions, 7 deletions

diff --git a/sys/compat/linux/linux_emul.h b/sys/compat/linux/linux_emul.h
index 3acde64..f409a34 100644
--- a/sys/compat/linux/linux_emul.h
+++ b/sys/compat/linux/linux_emul.h
@@ -64,13 +64,42 @@ struct linux_emuldata {
 
 struct linux_emuldata	*em_find(struct proc *, int locked);
 
-#define	EMUL_LOCK(l)		mtx_lock(l)
-#define	EMUL_UNLOCK(l)		mtx_unlock(l)
-
-#define	EMUL_SHARED_RLOCK(l)	sx_slock(l)
-#define	EMUL_SHARED_RUNLOCK(l)	sx_sunlock(l)
-#define	EMUL_SHARED_WLOCK(l)	sx_xlock(l)
-#define	EMUL_SHARED_WUNLOCK(l)	sx_xunlock(l)
+/*
+ * DTrace probes for locks should be fired after locking and before releasing
+ * to prevent races (to provide data/function stability in dtrace, see the
+ * output of "dtrace -v ..." and the corresponding dtrace docs).
+ */
+#define	EMUL_LOCK(l)		do { \
+				    mtx_lock(l); \
+				    LIN_SDT_PROBE1(locks, emul_lock, \
+					locked, l); \
+				} while (0)
+#define	EMUL_UNLOCK(l)		do { \
+				    LIN_SDT_PROBE1(locks, emul_lock, \
+					unlock, l); \
+				    mtx_unlock(l); \
+				} while (0)
+
+#define	EMUL_SHARED_RLOCK(l)	do { \
+				    sx_slock(l); \
+				    LIN_SDT_PROBE1(locks, emul_shared_rlock, \
+					locked, l); \
+				} while (0)
+#define	EMUL_SHARED_RUNLOCK(l)	do { \
+				    LIN_SDT_PROBE1(locks, emul_shared_rlock, \
+					unlock, l); \
+				    sx_sunlock(l); \
+				} while (0)
+#define	EMUL_SHARED_WLOCK(l)	do { \
+				    sx_xlock(l); \
+				    LIN_SDT_PROBE1(locks, emul_shared_wlock, \
+					locked, l); \
+				} while (0)
+#define	EMUL_SHARED_WUNLOCK(l)	do { \
+				    LIN_SDT_PROBE1(locks, emul_shared_wlock, \
+					unlock, l); \
+				    sx_xunlock(l); \
+				} while (0)
 
 /* for em_find use */
 #define	EMUL_DOLOCK		1