[Midnightbsd-cvs] src [8286] trunk/sys: until now KTR_ENTRIES, which define the size of the circular buffer used in ktr(4) were constrained to be a power of 2.

[laffer1 at midnightbsd.org]

Revision: 8286
          http://svnweb.midnightbsd.org/src/?rev=8286
Author:   laffer1
Date:     2016-09-17 18:06:50 -0400 (Sat, 17 Sep 2016)
Log Message:
-----------
until now KTR_ENTRIES, which define the size of the circular buffer used in ktr(4) were constrained to be a power of 2.

Modified Paths:
--------------
    trunk/sys/conf/NOTES
    trunk/sys/kern/kern_ktr.c

Modified: trunk/sys/conf/NOTES
===================================================================
--- trunk/sys/conf/NOTES	2016-09-17 22:06:03 UTC (rev 8285)
+++ trunk/sys/conf/NOTES	2016-09-17 22:06:50 UTC (rev 8286)
@@ -435,7 +435,7 @@
 #
 # KTR is a kernel tracing facility imported from BSD/OS.  It is
 # enabled with the KTR option.  KTR_ENTRIES defines the number of
-# entries in the circular trace buffer; it must be a power of two.
+# entries in the circular trace buffer; it may be an arbitrary number.
 # KTR_COMPILE defines the mask of events to compile into the kernel as
 # defined by the KTR_* constants in <sys/ktr.h>.  KTR_MASK defines the
 # initial value of the ktr_mask variable which determines at runtime

Modified: trunk/sys/kern/kern_ktr.c
===================================================================
--- trunk/sys/kern/kern_ktr.c	2016-09-17 22:06:03 UTC (rev 8285)
+++ trunk/sys/kern/kern_ktr.c	2016-09-17 22:06:50 UTC (rev 8286)
@@ -283,7 +283,7 @@
 	{
 		do {
 			saveindex = ktr_idx;
-			newindex = (saveindex + 1) & (KTR_ENTRIES - 1);
+			newindex = (saveindex + 1) % KTR_ENTRIES;
 		} while (atomic_cmpset_rel_int(&ktr_idx, saveindex, newindex) == 0);
 		entry = &ktr_buf[saveindex];
 	}
@@ -338,7 +338,7 @@
 DB_SHOW_COMMAND(ktr, db_ktr_all)
 {
 	
-	tstate.cur = (ktr_idx - 1) & (KTR_ENTRIES - 1);
+	tstate.cur = (ktr_idx - 1) % KTR_ENTRIES;
 	tstate.first = -1;
 	db_ktr_verbose = 0;
 	db_ktr_verbose |= (index(modif, 'v') != NULL) ? 2 : 0;