MFC r258311

opensolaris/uts/common/dtrace/fasttrap.c
        Fix several problems that can cause panics on kldload and kldunload.

        * kproc_create(fasttrap_pid_cleanup_cb, ...) gets called before
          fasttrap_provs.fth_table gets allocated.  This can lead to a panic
          on module load, because fasttrap_pid_cleanup_cb references
          fasttrap_provs.fth_table.  Move kproc_create down after the point
          that fasttrap_provs.fth_table gets allocated, and modify the error
          handling accordingly.

        * dtrace_fasttrap_{fork,exec,exit} weren't getting NULLed until
          after fasttrap_provs.fth_table got freed.  That caused panics on
          module unload because fasttrap_exec_exit calls
          fasttrap_provider_retire, which references
          fasttrap_provs.fth_table.  NULL those function pointers earlier.

        * There wasn't any code to destroy the
          fasttrap_{tpoints,provs,procs}.fth_table mutexes on module unload,
          leading to a resource leak when WITNESS is enabled.  Destroy those
          mutexes during fasttrap_unload().

Sponsored by:	Spectra Logic Corporation

1 files changed, 40 insertions, 23 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c b/sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c
index fd5508f..d72ee63 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c
@@ -2284,13 +2284,6 @@ fasttrap_load(void)
 	mutex_init(&fasttrap_count_mtx, "fasttrap count mtx", MUTEX_DEFAULT,
 	    NULL);
 
-	ret = kproc_create(fasttrap_pid_cleanup_cb, NULL,
-	    &fasttrap_cleanup_proc, 0, 0, "ftcleanup");
-	if (ret != 0) {
-		destroy_dev(fasttrap_cdev);
-		return (ret);
-	}
-
 #if defined(sun)
 	fasttrap_max = ddi_getprop(DDI_DEV_T_ANY, devi, DDI_PROP_DONTPASS,
 	    "fasttrap-max-probes", FASTTRAP_MAX_DEFAULT);
@@ -2344,6 +2337,24 @@ fasttrap_load(void)
 		    "providers bucket mtx", MUTEX_DEFAULT, NULL);
 #endif
 
+	ret = kproc_create(fasttrap_pid_cleanup_cb, NULL,
+	    &fasttrap_cleanup_proc, 0, 0, "ftcleanup");
+	if (ret != 0) {
+		destroy_dev(fasttrap_cdev);
+#if !defined(sun)
+		for (i = 0; i < fasttrap_provs.fth_nent; i++)
+			mutex_destroy(&fasttrap_provs.fth_table[i].ftb_mtx);
+		for (i = 0; i < fasttrap_tpoints.fth_nent; i++)
+			mutex_destroy(&fasttrap_tpoints.fth_table[i].ftb_mtx);
+#endif
+		kmem_free(fasttrap_provs.fth_table, fasttrap_provs.fth_nent *
+		    sizeof (fasttrap_bucket_t));
+		mtx_destroy(&fasttrap_cleanup_mtx);
+		mutex_destroy(&fasttrap_count_mtx);
+		return (ret);
+	}
+
+
 	/*
 	 * ... and the procs hash table.
 	 */
@@ -2436,6 +2447,20 @@ fasttrap_unload(void)
 		return (-1);
 	}
 
+	/*
+	 * Stop new processes from entering these hooks now, before the
+	 * fasttrap_cleanup thread runs.  That way all processes will hopefully
+	 * be out of these hooks before we free fasttrap_provs.fth_table
+	 */
+	ASSERT(dtrace_fasttrap_fork == &fasttrap_fork);
+	dtrace_fasttrap_fork = NULL;
+
+	ASSERT(dtrace_fasttrap_exec == &fasttrap_exec_exit);
+	dtrace_fasttrap_exec = NULL;
+
+	ASSERT(dtrace_fasttrap_exit == &fasttrap_exec_exit);
+	dtrace_fasttrap_exit = NULL;
+
 	mtx_lock(&fasttrap_cleanup_mtx);
 	fasttrap_cleanup_drain = 1;
 	/* Wait for the cleanup thread to finish up and signal us. */
@@ -2451,6 +2476,14 @@ fasttrap_unload(void)
 	mutex_exit(&fasttrap_count_mtx);
 #endif
 
+#if !defined(sun)
+	for (i = 0; i < fasttrap_tpoints.fth_nent; i++)
+		mutex_destroy(&fasttrap_tpoints.fth_table[i].ftb_mtx);
+	for (i = 0; i < fasttrap_provs.fth_nent; i++)
+		mutex_destroy(&fasttrap_provs.fth_table[i].ftb_mtx);
+	for (i = 0; i < fasttrap_procs.fth_nent; i++)
+		mutex_destroy(&fasttrap_procs.fth_table[i].ftb_mtx);
+#endif
 	kmem_free(fasttrap_tpoints.fth_table,
 	    fasttrap_tpoints.fth_nent * sizeof (fasttrap_bucket_t));
 	fasttrap_tpoints.fth_nent = 0;
@@ -2463,22 +2496,6 @@ fasttrap_unload(void)
 	    fasttrap_procs.fth_nent * sizeof (fasttrap_bucket_t));
 	fasttrap_procs.fth_nent = 0;
 
-	/*
-	 * We know there are no tracepoints in any process anywhere in
-	 * the system so there is no process which has its p_dtrace_count
-	 * greater than zero, therefore we know that no thread can actively
-	 * be executing code in fasttrap_fork(). Similarly for p_dtrace_probes
-	 * and fasttrap_exec() and fasttrap_exit().
-	 */
-	ASSERT(dtrace_fasttrap_fork == &fasttrap_fork);
-	dtrace_fasttrap_fork = NULL;
-
-	ASSERT(dtrace_fasttrap_exec == &fasttrap_exec_exit);
-	dtrace_fasttrap_exec = NULL;
-
-	ASSERT(dtrace_fasttrap_exit == &fasttrap_exec_exit);
-	dtrace_fasttrap_exit = NULL;
-
 #if !defined(sun)
 	destroy_dev(fasttrap_cdev);
 	mutex_destroy(&fasttrap_count_mtx);