Author: markj
Date: Tue Oct  8 12:56:46 2013
New Revision: 256148
URL: http://svnweb.freebsd.org/changeset/base/256148

Log:
  Initialize and free the DTrace taskqueue in the dtrace module load/unload
  handlers rather than in the dtrace device open/close methods. The current
  approach can cause a panic if the device is closed which the taskqueue
  thread is active, or if a kernel module containing a provider is unloaded
  while retained enablings are present and the dtrace device isn't opened.
  
  Submitted by: gibbs (original version)
  Reviewed by:  gibbs
  Approved by:  re (glebius)
  MFC after:    2 weeks

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

Modified: head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c        Tue Oct 
 8 12:42:52 2013        (r256147)
+++ head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c        Tue Oct 
 8 12:56:46 2013        (r256148)
@@ -15751,10 +15751,6 @@ dtrace_open(struct cdev *dev, int oflags
 #else
        devfs_set_cdevpriv(state, dtrace_dtr);
 #endif
-       /* This code actually belongs in dtrace_attach() */
-       if (dtrace_opens == 1)
-               dtrace_taskq = taskq_create("dtrace_taskq", 1, maxclsyspri,
-                   1, INT_MAX, 0);
 #endif
 
        mutex_exit(&cpu_lock);
@@ -15842,11 +15838,6 @@ dtrace_dtr(void *data)
                (void) kdi_dtrace_set(KDI_DTSET_DTRACE_DEACTIVATE);
 #else
        --dtrace_opens;
-       /* This code actually belongs in dtrace_detach() */
-       if ((dtrace_opens == 0) && (dtrace_taskq != NULL)) {
-               taskq_destroy(dtrace_taskq);
-               dtrace_taskq = NULL;
-       }
 #endif
 
        mutex_exit(&dtrace_lock);

Modified: head/sys/cddl/dev/dtrace/dtrace_load.c
==============================================================================
--- head/sys/cddl/dev/dtrace/dtrace_load.c      Tue Oct  8 12:42:52 2013        
(r256147)
+++ head/sys/cddl/dev/dtrace/dtrace_load.c      Tue Oct  8 12:56:46 2013        
(r256148)
@@ -56,6 +56,8 @@ dtrace_load(void *dummy)
        /* Hang our hook for exceptions. */
        dtrace_invop_init();
 
+       dtrace_taskq = taskq_create("dtrace_taskq", 1, maxclsyspri, 0, 0, 0);
+
        /* Register callbacks for linker file load and unload events. */
        dtrace_kld_load_tag = EVENTHANDLER_REGISTER(kld_load,
            dtrace_kld_load, NULL, EVENTHANDLER_PRI_ANY);

Modified: head/sys/cddl/dev/dtrace/dtrace_unload.c
==============================================================================
--- head/sys/cddl/dev/dtrace/dtrace_unload.c    Tue Oct  8 12:42:52 2013        
(r256147)
+++ head/sys/cddl/dev/dtrace/dtrace_unload.c    Tue Oct  8 12:56:46 2013        
(r256148)
@@ -127,6 +127,8 @@ dtrace_unload()
        mutex_destroy(&dtrace_errlock);
 #endif
 
+       taskq_destroy(dtrace_taskq);
+
        /* Reset our hook for exceptions. */
        dtrace_invop_uninit();
 
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