gdb/linux-nat: factor ptrace-detach code to new detach_one_pid function

The following patch will add some code paths that need to ptrace-detach
a given PID.  Factor out the code that does this and put it in its own
function, so that it can be re-used.

Change-Id: Ie65ca0d89893b41aea0a23d9fc6ffbed042a9705

gdb/linux-nat.c

@@ -1234,6 +1234,45 @@ linux_nat_target::attach (const char *args, int from_tty)
     target_async (1);
 }
 
+/* Ptrace-detach the thread with pid PID.  */
+
+static void
+detach_one_pid (int pid, int signo)
+{
+  if (ptrace (PTRACE_DETACH, pid, 0, signo) < 0)
+    {
+      int save_errno = errno;
+
+      /* We know the thread exists, so ESRCH must mean the lwp is
+	 zombie.  This can happen if one of the already-detached
+	 threads exits the whole thread group.  In that case we're
+	 still attached, and must reap the lwp.  */
+      if (save_errno == ESRCH)
+	{
+	  int ret, status;
+
+	  ret = my_waitpid (pid, &status, __WALL);
+	  if (ret == -1)
+	    {
+	      warning (_("Couldn't reap LWP %d while detaching: %s"),
+		       pid, safe_strerror (errno));
+	    }
+	  else if (!WIFEXITED (status) && !WIFSIGNALED (status))
+	    {
+	      warning (_("Reaping LWP %d while detaching "
+			 "returned unexpected status 0x%x"),
+		       pid, status);
+	    }
+	}
+      else
+	error (_("Can't detach %d: %s"),
+	       pid, safe_strerror (save_errno));
+    }
+  else
+    linux_nat_debug_printf ("PTRACE_DETACH (%d, %s, 0) (OK)",
+			    pid, strsignal (signo));
+}
+
 /* Get pending signal of THREAD as a host signal number, for detaching
    purposes.  This is the signal the thread last stopped for, which we
    need to deliver to the thread when detaching, otherwise, it'd be
@@ -1364,42 +1403,7 @@ detach_one_lwp (struct lwp_info *lp, int *signo_p)
 	throw;
     }
 
-  if (ptrace (PTRACE_DETACH, lwpid, 0, signo) < 0)
-    {
-      int save_errno = errno;
-
-      /* We know the thread exists, so ESRCH must mean the lwp is
-	 zombie.  This can happen if one of the already-detached
-	 threads exits the whole thread group.  In that case we're
-	 still attached, and must reap the lwp.  */
-      if (save_errno == ESRCH)
-	{
-	  int ret, status;
-
-	  ret = my_waitpid (lwpid, &status, __WALL);
-	  if (ret == -1)
-	    {
-	      warning (_("Couldn't reap LWP %d while detaching: %s"),
-		       lwpid, safe_strerror (errno));
-	    }
-	  else if (!WIFEXITED (status) && !WIFSIGNALED (status))
-	    {
-	      warning (_("Reaping LWP %d while detaching "
-			 "returned unexpected status 0x%x"),
-		       lwpid, status);
-	    }
-	}
-      else
-	{
-	  error (_("Can't detach %s: %s"),
-		 target_pid_to_str (lp->ptid).c_str (),
-		 safe_strerror (save_errno));
-	}
-    }
-  else
-    linux_nat_debug_printf ("PTRACE_DETACH (%s, %s, 0) (OK)",
-			    target_pid_to_str (lp->ptid).c_str (),
-			    strsignal (signo));
+  detach_one_pid (lwpid, signo);
 
   delete_lwp (lp->ptid);
 }