Unify the checking for lock misbehavior in the various syscall()

implementations and adjust some of the checks while I'm here:
- Add a new check to make sure we don't return from a syscall in a critical
  section.
- Add a new explicit check before userret() to make sure we don't return
  with any locks held.  The advantage here is that we can include the
  syscall number and name in syscall() whereas that info is not available
  in userret().
- Drop the mtx_assert()'s of sched_lock and Giant.  They are replaced by
  the more general checks just added.

MFC after:	2 weeks

1 files changed, 13 insertions, 7 deletions

diff --git a/sys/ia64/ia32/ia32_trap.c b/sys/ia64/ia32/ia32_trap.c
index c3cacf5..f63ae94 100644
--- a/sys/ia64/ia32/ia32_trap.c
+++ b/sys/ia64/ia32/ia32_trap.c
@@ -46,9 +46,7 @@ __FBSDID("$FreeBSD$");
 #include <machine/md_var.h>
 #include <i386/include/psl.h>
 
-#ifdef WITNESS
 extern char *syscallnames[];
-#endif
 
 static void
 ia32_syscall(struct trapframe *tf)
@@ -183,6 +181,19 @@ ia32_syscall(struct trapframe *tf)
 	}
 
 	/*
+	 * Check for misbehavior.
+	 */
+	WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning",
+	    (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???");
+	KASSERT(td->td_critnest == 0,
+	    ("System call %s returning in a critical section",
+	    (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???"));
+	KASSERT(td->td_locks == 0,
+	    ("System call %s returning with %d locks held",
+	    (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???",
+	    td->td_locks));
+
+	/*
 	 * End of syscall tracing.
 	 */
 	CTR4(KTR_SYSC, "syscall exit thread %p pid %d proc %s code %d", td,
@@ -200,11 +211,6 @@ ia32_syscall(struct trapframe *tf)
 	STOPEVENT(p, S_SCX, code);
  
 	PTRACESTOP_SC(p, td, S_PT_SCX);
-
-	WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning",
-	    (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???");
-	mtx_assert(&sched_lock, MA_NOTOWNED);
-	mtx_assert(&Giant, MA_NOTOWNED);
 }
 
 /*