4159 dtrace ignores all ustack helper frames from dead processes
Reviewed by: Bryan Cantrill <bryan@joyent.com>
Reviewed by: Robert Mustacchi <rm@joyent.com>

*** 1379,1390 ****
                          } else {
                                  (void) snprintf(c, sizeof (c),
                                      "%s`%s", dt_basename(objname), name);
                          }
                  } else if (str != NULL && str[0] != '\0' && str[0] != '@' &&
!                     (P != NULL && ((map = Paddr_to_map(P, pc[i])) == NULL ||
!                     (map->pr_mflags & MA_WRITE)))) {
                          /*
                           * If the current string pointer in the string table
                           * does not point to an empty string _and_ the program
                           * counter falls in a writable region, we'll use the
                           * string from the string table instead of the raw
--- 1379,1390 ----
                          } else {
                                  (void) snprintf(c, sizeof (c),
                                      "%s`%s", dt_basename(objname), name);
                          }
                  } else if (str != NULL && str[0] != '\0' && str[0] != '@' &&
!                     (P == NULL || (map = Paddr_to_map(P, pc[i])) == NULL ||
!                     map->pr_mflags & MA_WRITE)) {
                          /*
                           * If the current string pointer in the string table
                           * does not point to an empty string _and_ the program
                           * counter falls in a writable region, we'll use the
                           * string from the string table instead of the raw
*** 1392,1402 ****
                           * some (broken) ustack helpers will return a string
                           * even for a program counter that they can't
                           * identify.  If we have a string for a program
                           * counter that falls in a segment that isn't
                           * writable, we assume that we have fallen into this
!                          * case and we refuse to use the string.
                           */
                          (void) snprintf(c, sizeof (c), "%s", str);
                  } else {
                          if (P != NULL && Pobjname(P, pc[i], objname,
                              sizeof (objname)) != NULL) {
--- 1392,1405 ----
                           * some (broken) ustack helpers will return a string
                           * even for a program counter that they can't
                           * identify.  If we have a string for a program
                           * counter that falls in a segment that isn't
                           * writable, we assume that we have fallen into this
!                          * case and we refuse to use the string.  Finally,
!                          * note that if we could not grab the process (e.g.,
!                          * because it exited), the information from the helper
!                          * is better than nothing.
                           */
                          (void) snprintf(c, sizeof (c), "%s", str);
                  } else {
                          if (P != NULL && Pobjname(P, pc[i], objname,
                              sizeof (objname)) != NULL) {