gdb/testsuite/gdb.threads/continue-pending-status.exp

   1 # Copyright (C) 2015-2016 Free Software Foundation, Inc.
   2
   3 # This program is free software; you can redistribute it and/or modify
   4 # it under the terms of the GNU General Public License as published by
   5 # the Free Software Foundation; either version 3 of the License, or
   6 # (at your option) any later version.
   7 #
   8 # This program is distributed in the hope that it will be useful,
   9 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 # GNU General Public License for more details.
  12 #
  13 # You should have received a copy of the GNU General Public License
  14 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15
  16 # This test exercises the case of stopping for a breakpoint hit of one
  17 # thread, then switching to a thread that has a status pending and
  18 # continuing.
  19
  20 if [target_info exists gdb,nointerrupts] {
  21     verbose "Skipping continue-pending-status.exp because of nointerrupts."
  22     return
  23 }
  24
  25 standard_testfile
  26
  27 if [prepare_for_testing "failed to prepare" $testfile $srcfile {debug pthreads}] {
  28     return -1
  29 }
  30
  31 if ![runto_main] {
  32     untested "could not run to main"
  33     return -1
  34 }
  35
  36 set break_line [gdb_get_line_number "break here"]
  37
  38 # Return current thread's number.
  39
  40 proc get_current_thread {} {
  41     global gdb_prompt
  42
  43     set thread ""
  44     set msg "get thread number"
  45     gdb_test_multiple "print /x \$_thread" $msg {
  46         -re "\\$\[0-9\]* = (0x\[0-9a-zA-Z\]+).*$gdb_prompt $" {
  47             set thread $expect_out(1,string)
  48             pass "$msg"
  49         }
  50     }
  51     return ${thread}
  52 }
  53
  54 # There are two threads in the program that are running the same tight
  55 # loop, where we place a breakpoint.  Sometimes we'll get a breakpoint
  56 # trigger for thread 2, with the breakpoint event of thread 3 pending,
  57 # other times the opposite.  The original bug that motivated this test
  58 # depended on the event thread being the highest numbered thread.  We
  59 # try the same multiple times, which should cover both threads
  60 # reporting the event.
  61
  62 set attempts 20
  63
  64 # These track whether we saw events for both threads 2 and 3.  If the
  65 # backend always returns the breakpoint hit for the same thread, then
  66 # it fails to make sure threads aren't starved, and we'll fail the
  67 # assert after the loop.
  68 set saw_thread_2 0
  69 set saw_thread_3 0
  70
  71 for {set i 0} {$i < $attempts} {incr i} {
  72     with_test_prefix "attempt $i" {
  73         gdb_test "b $srcfile:$break_line" \
  74             "Breakpoint .* at .*$srcfile, line $break_line.*" \
  75             "set break in tight loop"
  76         gdb_test "continue" \
  77             "$srcfile:$break_line.*" \
  78             "continue to tight loop"
  79
  80         # Switch to the thread that did _not_ report the event (and
  81         # thus may have a pending status).  At the time this test was
  82         # written this was necessary to make linux-nat.c short-circuit
  83         # the resume and go straight to consuming the pending event.
  84         set thread [get_current_thread]
  85         if {$thread == 2} {
  86             incr saw_thread_2
  87             set thread 3
  88         } else {
  89             incr saw_thread_3
  90             set thread 2
  91         }
  92         gdb_test "thread $thread" \
  93             "Switching to thread $thread .*" \
  94             "switch to non-event thread"
  95
  96         # Delete all breakpoints so that continuing doesn't switch
  97         # back to the event thread to do a step-over, which would mask
  98         # away the original bug, which depended on the event thread
  99         # still having TARGET_STOPPED_BY_SW_BREAKPOINT stop_reason.
 100         delete_breakpoints
 101
 102         # In the original bug, continuing would trigger an internal
 103         # error in the linux-nat.c backend.
 104
 105         set msg "continue for ctrl-c"
 106         gdb_test_multiple "continue" $msg {
 107             -re "Continuing" {
 108                 pass $msg
 109             }
 110         }
 111
 112         # Wait a bit for GDB to give the terminal to the inferior,
 113         # otherwise ctrl-c too soon can result in a "Quit".
 114         sleep 1
 115         send_gdb "\003"
 116
 117         set msg "caught interrupt"
 118         gdb_test_multiple "" $msg {
 119             -re "Thread .* received signal SIGINT.*$gdb_prompt $" {
 120                 pass $msg
 121             }
 122         }
 123     }
 124 }
 125
 126 verbose -log "saw_thread_2=$saw_thread_2"
 127 verbose -log "saw_thread_3=$saw_thread_3"
 128
 129 gdb_assert {$saw_thread_2 > 0 && $saw_thread_3 > 0} "no thread starvation"