gdb: remove solib::pspace field

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index f9b20a7d62d1..f378edf865ea 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -8018,7 +8018,7 @@  disable_breakpoints_in_shlibs (void)
    disabled ones can just stay disabled.  */
 
 static void
-disable_breakpoints_in_unloaded_shlib (struct so_list *solib)
+disable_breakpoints_in_unloaded_shlib (program_space *pspace, so_list *solib)
 {
   bool disabled_shlib_breaks = false;
 
@@ -8027,7 +8027,7 @@  disable_breakpoints_in_unloaded_shlib (struct so_list *solib)
       /* ALL_BP_LOCATIONS bp_location has LOC->OWNER always non-NULL.  */
       struct breakpoint *b = loc->owner;
 
-      if (solib->pspace == loc->pspace
+      if (pspace == loc->pspace
 	  && !loc->shlib_disabled
 	  && (((b->type == bp_breakpoint
 		|| b->type == bp_jit_event
diff --git a/gdb/bsd-uthread.c b/gdb/bsd-uthread.c
index d5c6fdd36395..e27e88add869 100644
--- a/gdb/bsd-uthread.c
+++ b/gdb/bsd-uthread.c
@@ -294,7 +294,7 @@  bsd_uthread_solib_loaded (struct so_list *so)
 }
 
 static void
-bsd_uthread_solib_unloaded (struct so_list *so)
+bsd_uthread_solib_unloaded (program_space *pspace, so_list *so)
 {
   if (!bsd_uthread_solib_name)
     return;
diff --git a/gdb/observable.h b/gdb/observable.h
index 4ea203c6fc38..b57c3a201741 100644
--- a/gdb/observable.h
+++ b/gdb/observable.h
@@ -93,10 +93,11 @@  extern observable<inferior */* parent_inf */, inferior */* child_inf */,
    haven't been loaded yet.  */
 extern observable<struct so_list */* solib */> solib_loaded;
 
-/* The shared library specified by SOLIB has been unloaded.  Note
-   that when gdb calls this observer, the library's symbols have not
+/* The shared library SOLIB has been unloaded from program space PSPACE.
+   Note  when gdb calls this observer, the library's symbols have not
    been unloaded yet, and thus are still available.  */
-extern observable<struct so_list */* solib */> solib_unloaded;
+extern observable<struct program_space */* pspace */, struct so_list */* solib */>
+  solib_unloaded;
 
 /* The symbol file specified by OBJFILE has been loaded.  Called
    with OBJFILE equal to NULL to indicate previously loaded symbol
diff --git a/gdb/solib.c b/gdb/solib.c
index 771954e51c8f..f2735b37927e 100644
--- a/gdb/solib.c
+++ b/gdb/solib.c
@@ -769,10 +769,10 @@  notify_solib_loaded (so_list *so)
 /* Notify interpreters and observers that solib SO has been unloaded.  */
 
 static void
-notify_solib_unloaded (so_list *so)
+notify_solib_unloaded (program_space *pspace, so_list *so)
 {
   interps_notify_solib_unloaded (so);
-  gdb::observers::solib_unloaded.notify (so);
+  gdb::observers::solib_unloaded.notify (pspace, so);
 }
 
 /* See solib.h.  */
@@ -875,7 +875,7 @@  update_solib_list (int from_tty)
 	{
 	  /* Notify any observer that the shared object has been
 	     unloaded before we remove it from GDB's tables.  */
-	  notify_solib_unloaded (gdb);
+	  notify_solib_unloaded (current_program_space, gdb);
 
 	  current_program_space->deleted_solibs.push_back (gdb->so_name);
 
@@ -911,8 +911,6 @@  update_solib_list (int from_tty)
       /* Fill in the rest of each of the `struct so_list' nodes.  */
       for (i = inferior; i; i = i->next)
 	{
-
-	  i->pspace = current_program_space;
 	  current_program_space->added_solibs.push_back (i);
 
 	  try
@@ -1243,7 +1241,7 @@  clear_solib (void)
       struct so_list *so = current_program_space->so_list;
 
       current_program_space->so_list = so->next;
-      notify_solib_unloaded (so);
+      notify_solib_unloaded (current_program_space, so);
       current_program_space->remove_target_sections (so);
       free_so (so);
     }
diff --git a/gdb/solist.h b/gdb/solist.h
index 5275a79d811c..0f764b264f74 100644
--- a/gdb/solist.h
+++ b/gdb/solist.h
@@ -55,9 +55,6 @@  struct so_list
   /* Shared object file name, expanded to something GDB can open.  */
   char so_name[SO_NAME_MAX_PATH_SIZE];
 
-  /* Program space this shared library belongs to.  */
-  struct program_space *pspace;
-
   /* The following fields of the structure are built from
      information gathered from the shared object file itself, and
      are set when we actually add it to our symbol tables.