Provide helper macros to detect 'non-silent SBDRY' state and to

calculate appropriate return value for stops.  Simplify the code by
using them.

Fix typo in sig_suspend_threads().  The thread which sleep must be
aborted is td2. (*)

In issignal(), when handling stopping signal for thread in
TD_SBDRY_INTR state, do not stop, this is wrong and fires assert.
This is yet another place where execution should be forced out of
SBDRY-protected region.  For such case, return -1 from issignal() and
translate it to corresponding error code in sleepq_catch_signals().
Assert that other consumers of cursig() are not affected by the new
return value. (*)

Micro-optimize, mostly VFS and VOP methods, by avoiding calling the
functions when SIGDEFERSTOP_NOP non-change is requested. (**)

Reported and tested by:	pho (*)
Requested by:	bde (**)
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Approved by:	re (gjb)

1 files changed, 5 insertions, 16 deletions

diff --git a/sys/kern/kern_thread.c b/sys/kern/kern_thread.c
index 5a2d392..89eb7db 100644
--- a/sys/kern/kern_thread.c
+++ b/sys/kern/kern_thread.c
@@ -894,7 +894,7 @@ thread_suspend_check(int return_instead)
 {
 	struct thread *td;
 	struct proc *p;
-	int wakeup_swapper, r;
+	int wakeup_swapper;
 
 	td = curthread;
 	p = td->td_proc;
@@ -927,21 +927,10 @@ thread_suspend_check(int return_instead)
 		if ((td->td_flags & TDF_SBDRY) != 0) {
 			KASSERT(return_instead,
 			    ("TDF_SBDRY set for unsafe thread_suspend_check"));
-			switch (td->td_flags & (TDF_SEINTR | TDF_SERESTART)) {
-			case 0:
-				r = 0;
-				break;
-			case TDF_SEINTR:
-				r = EINTR;
-				break;
-			case TDF_SERESTART:
-				r = ERESTART;
-				break;
-			default:
-				panic("both TDF_SEINTR and TDF_SERESTART");
-				break;
-			}
-			return (r);
+			KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) !=
+			    (TDF_SEINTR | TDF_SERESTART),
+			    ("both TDF_SEINTR and TDF_SERESTART"));
+			return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0);
 		}
 
 		/*