Remove save_inferior_ptid

This removes save_inferior_ptid, a cleanup function, in favor of
scoped_restore.

This also fixes a possible (it seems unlikely that it could happen in
practice) memory leak -- save_inferior_ptid should have used
make_cleanup_dtor, because it allocated memory.

I tested this on the buildbot.  However, there are two caveats to
this.  First, sometimes it seems I misread the results.  Second, I
think this patch touches some platforms that can't be tested by the
buildbot.  So, extra care seems warranted.

ChangeLog
2017-08-18  Tom Tromey  <tom@tromey.com>
	    Pedro Alves  <palves@redhat.com>

	* spu-multiarch.c (parse_spufs_run): Use scoped_restore.
	* sol-thread.c (sol_thread_resume, sol_thread_wait)
	(sol_thread_xfer_partial, rw_common): Use scoped_restore.
	* procfs.c (procfs_do_thread_registers): Use scoped_restore.
	* proc-service.c (ps_xfer_memory): Use scoped_restore.
	* linux-tdep.c (linux_corefile_thread): Remove a cleanup.
	(linux_get_siginfo_data): Add "thread" argument.  Use
	scoped_restore.
	* linux-nat.c (linux_child_follow_fork)
	(check_stopped_by_watchpoint): Use scoped_restore.
	* infrun.c (displaced_step_prepare_throw, write_memory_ptid)
	(THREAD_STOPPED_BY, handle_signal_stop): Use scoped_restore.
	(restore_inferior_ptid, save_inferior_ptid): Remove.
	* btrace.c (btrace_fetch): Use scoped_restore.
	* bsd-uthread.c (bsd_uthread_fetch_registers)
	(bsd_uthread_store_registers): Use scoped_restore.
	* breakpoint.c (reattach_breakpoints, detach_breakpoints): Use
	scoped_restore.
	* aix-thread.c (aix_thread_resume, aix_thread_wait)
	(aix_thread_xfer_partial): Use scoped_restore.
	* inferior.h (save_inferior_ptid): Remove.

1 files changed, 9 insertions, 14 deletions

diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index b9c7d1f..4124318 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -477,7 +477,6 @@ linux_child_follow_fork (struct target_ops *ops, int follow_child,
     {
       struct lwp_info *child_lp = NULL;
       int status = W_STOPCODE (0);
-      struct cleanup *old_chain;
       int has_vforked;
       ptid_t parent_ptid, child_ptid;
       int parent_pid, child_pid;
@@ -490,16 +489,15 @@ linux_child_follow_fork (struct target_ops *ops, int follow_child,
       child_pid = ptid_get_lwp (child_ptid);
 
       /* We're already attached to the parent, by default.  */
-      old_chain = save_inferior_ptid ();
-      inferior_ptid = child_ptid;
-      child_lp = add_lwp (inferior_ptid);
+      child_lp = add_lwp (child_ptid);
       child_lp->stopped = 1;
       child_lp->last_resume_kind = resume_stop;
 
       /* Detach new forked process?  */
       if (detach_fork)
 	{
-	  make_cleanup (delete_lwp_cleanup, child_lp);
+	  struct cleanup *old_chain = make_cleanup (delete_lwp_cleanup,
+						    child_lp);
 
 	  if (linux_nat_prepare_to_resume != NULL)
 	    linux_nat_prepare_to_resume (child_lp);
@@ -513,7 +511,7 @@ linux_child_follow_fork (struct target_ops *ops, int follow_child,
 	     once before detaching to clear the flags.  */
 
 	  if (!gdbarch_software_single_step_p (target_thread_architecture
-						   (child_lp->ptid)))
+					       (child_lp->ptid)))
 	    {
 	      linux_disable_event_reporting (child_pid);
 	      if (ptrace (PTRACE_SINGLESTEP, child_pid, 0, 0) < 0)
@@ -533,17 +531,18 @@ linux_child_follow_fork (struct target_ops *ops, int follow_child,
 	      ptrace (PTRACE_DETACH, child_pid, 0, signo);
 	    }
 
-	  /* Resets value of inferior_ptid to parent ptid.  */
 	  do_cleanups (old_chain);
 	}
       else
 	{
+	  scoped_restore save_inferior_ptid
+	    = make_scoped_restore (&inferior_ptid);
+	  inferior_ptid = child_ptid;
+
 	  /* Let the thread_db layer learn about this new process.  */
 	  check_for_thread_db ();
 	}
 
-      do_cleanups (old_chain);
-
       if (has_vforked)
 	{
 	  struct lwp_info *parent_lp;
@@ -2458,12 +2457,10 @@ maybe_clear_ignore_sigint (struct lwp_info *lp)
 static int
 check_stopped_by_watchpoint (struct lwp_info *lp)
 {
-  struct cleanup *old_chain;
-
   if (linux_ops->to_stopped_by_watchpoint == NULL)
     return 0;
 
-  old_chain = save_inferior_ptid ();
+  scoped_restore save_inferior_ptid = make_scoped_restore (&inferior_ptid);
   inferior_ptid = lp->ptid;
 
   if (linux_ops->to_stopped_by_watchpoint (linux_ops))
@@ -2478,8 +2475,6 @@ check_stopped_by_watchpoint (struct lwp_info *lp)
 	lp->stopped_data_address_p = 0;
     }
 
-  do_cleanups (old_chain);
-
   return lp->stop_reason == TARGET_STOPPED_BY_WATCHPOINT;
 }