svn commit: r268130 - head/sys/cddl/contrib/opensolaris/uts/common/dtrace

[Pedro F. Giffuni]

Author: pfg
Date: Tue Jul  1 23:37:24 2014
New Revision: 268130
URL: http://svnweb.freebsd.org/changeset/base/268130

Log:
  Merge from OpenSolaris (15-Sep-2008):
  
  6735480 race between probe enabling and provider registration
  
  MFC after:	1 week

Modified:
  head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c

Modified: head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c	Tue Jul  1 22:46:39 2014	(r268129)
+++ head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c	Tue Jul  1 23:37:24 2014	(r268130)
@@ -27,8 +27,6 @@
  * Copyright (c) 2012 by Delphix. All rights reserved.
  */
 
-#pragma ident	"%Z%%M%	%I%	%E% SMI"
-
 /*
  * DTrace - Dynamic Tracing for Solaris
  *
@@ -238,6 +236,7 @@ static dtrace_ecb_t	*dtrace_ecb_create_c
 static dtrace_genid_t	dtrace_probegen;	/* current probe generation */
 static dtrace_helpers_t *dtrace_deferred_pid;	/* deferred helper list */
 static dtrace_enabling_t *dtrace_retained;	/* list of retained enablings */
+static dtrace_genid_t	dtrace_retained_gen;	/* current retained enab gen */
 static dtrace_dynvar_t	dtrace_dynhash_sink;	/* end of dynamic hash chains */
 #if !defined(sun)
 static struct mtx	dtrace_unr_mtx;
@@ -12393,6 +12392,7 @@ dtrace_enabling_destroy(dtrace_enabling_
 		ASSERT(enab->dten_vstate->dtvs_state != NULL);
 		ASSERT(enab->dten_vstate->dtvs_state->dts_nretained > 0);
 		enab->dten_vstate->dtvs_state->dts_nretained--;
+		dtrace_retained_gen++;
 	}
 
 	if (enab->dten_prev == NULL) {
@@ -12435,6 +12435,7 @@ dtrace_enabling_retain(dtrace_enabling_t
 		return (ENOSPC);
 
 	state->dts_nretained++;
+	dtrace_retained_gen++;
 
 	if (dtrace_retained == NULL) {
 		dtrace_retained = enab;
@@ -12677,6 +12678,7 @@ dtrace_enabling_provide(dtrace_provider_
 {
 	int i, all = 0;
 	dtrace_probedesc_t desc;
+	dtrace_genid_t gen;
 
 	ASSERT(MUTEX_HELD(&dtrace_lock));
 	ASSERT(MUTEX_HELD(&dtrace_provider_lock));
@@ -12687,15 +12689,25 @@ dtrace_enabling_provide(dtrace_provider_
 	}
 
 	do {
-		dtrace_enabling_t *enab = dtrace_retained;
+		dtrace_enabling_t *enab;
 		void *parg = prv->dtpv_arg;
 
-		for (; enab != NULL; enab = enab->dten_next) {
+retry:
+		gen = dtrace_retained_gen;
+		for (enab = dtrace_retained; enab != NULL;
+		    enab = enab->dten_next) {
 			for (i = 0; i < enab->dten_ndesc; i++) {
 				desc = enab->dten_desc[i]->dted_probe;
 				mutex_exit(&dtrace_lock);
 				prv->dtpv_pops.dtps_provide(parg, &desc);
 				mutex_enter(&dtrace_lock);
+				/*
+				 * Process the retained enablings again if
+				 * they have changed while we weren't holding
+				 * dtrace_lock.
+				 */
+				if (gen != dtrace_retained_gen)
+					goto retry;
 			}
 		}
 	} while (all && (prv = prv->dtpv_next) != NULL);