old-cross-binutils/gdb/testsuite/gdb.threads/signal-command-multiple-signals-pending.exp
Pedro Alves f303dbd60d Fix PR threads/19422 - show which thread caused stop
This commit changes GDB like this:

 - Program received signal SIGINT, Interrupt.
 + Thread 1 "main" received signal SIGINT, Interrupt.

 - Breakpoint 1 at 0x40087a: file threads.c, line 87.
 + Thread 3 "bar" hit Breakpoint 1 at 0x40087a: file threads.c, line 87.

 ... once the program goes multi-threaded.  Until GDB sees a second
thread spawn, the output is still the same as before, per the
discussion back in 2012:

  https://www.sourceware.org/ml/gdb/2012-11/msg00010.html

This helps non-stop mode, where you can't easily tell which thread hit
a breakpoint or received a signal:

 (gdb) info threads
   Id   Target Id         Frame
 * 1    Thread 0x7ffff7fc1740 (LWP 19362) "main" (running)
   2    Thread 0x7ffff7fc0700 (LWP 19366) "foo" (running)
   3    Thread 0x7ffff77bf700 (LWP 19367) "bar" (running)
 (gdb)
 Program received signal SIGUSR1, User defined signal 1.
 0x0000003616a09237 in pthread_join (threadid=140737353877248, thread_return=0x7fffffffd5b8) at pthread_join.c:92
 92          lll_wait_tid (pd->tid);
 (gdb) b threads.c:87
 Breakpoint 1 at 0x40087a: file threads.c, line 87.
 (gdb)
 Breakpoint 1, thread_function1 (arg=0x1) at threads.c:87
 87              usleep (1);  /* Loop increment.  */

The best the user can do is run "info threads" and try to figure
things out.

It actually also affects all-stop mode, in case of "handle SIG print
nostop":

...
  Program received signal SIGUSR1, User defined signal 1.

  Program received signal SIGUSR1, User defined signal 1.

  Program received signal SIGUSR1, User defined signal 1.

  Program received signal SIGUSR1, User defined signal 1.
...

The above doesn't give any clue that these were different threads
getting the SIGUSR1 signal.

I initially thought of lowercasing "breakpoint" in

  "Thread 3 hit Breakpoint 1"

but then after trying it I realized that leaving "Breakpoint"
uppercase helps the eye quickly find the relevant information.  It's
also easier to implement not showing anything about threads until the
program goes multi-threaded this way.

Here's a larger example session in non-stop mode:

  (gdb) c -a&
  Continuing.
  (gdb) interrupt -a
  (gdb)
  Thread 1 "main" stopped.
  0x0000003616a09237 in pthread_join (threadid=140737353877248, thread_return=0x7fffffffd5b8) at pthread_join.c:92
  92          lll_wait_tid (pd->tid);

  Thread 2 "foo" stopped.
  0x0000003615ebc6ed in nanosleep () at ../sysdeps/unix/syscall-template.S:81
  81      T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)

  Thread 3 "bar" stopped.
  0x0000003615ebc6ed in nanosleep () at ../sysdeps/unix/syscall-template.S:81
  81      T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
  b threads.c:87
  Breakpoint 4 at 0x40087a: file threads.c, line 87.
  (gdb) b threads.c:67
  Breakpoint 5 at 0x400811: file threads.c, line 67.
  (gdb) c -a&
  Continuing.
  (gdb)
  Thread 3 "bar" hit Breakpoint 4, thread_function1 (arg=0x1) at threads.c:87
  87              usleep (1);  /* Loop increment.  */

  Thread 2 "foo" hit Breakpoint 5, thread_function0 (arg=0x0) at threads.c:68
  68              (*myp) ++;
  info threads
    Id   Target Id         Frame
  * 1  Thread 0x7ffff7fc1740 (LWP 31957) "main" (running)
    2  Thread 0x7ffff7fc0700 (LWP 31961) "foo" thread_function0 (arg=0x0) at threads.c:68
    3  Thread 0x7ffff77bf700 (LWP 31962) "bar" thread_function1 (arg=0x1) at threads.c:87
  (gdb) shell kill -SIGINT 31957
  (gdb)
  Thread 1 "main" received signal SIGINT, Interrupt.
  0x0000003616a09237 in pthread_join (threadid=140737353877248, thread_return=0x7fffffffd5b8) at pthread_join.c:92
  92          lll_wait_tid (pd->tid);
  info threads
    Id   Target Id         Frame
  * 1  Thread 0x7ffff7fc1740 (LWP 31957) "main" 0x0000003616a09237 in pthread_join (threadid=140737353877248, thread_return=0x7fffffffd5b8) at pthread_join.c:92
    2  Thread 0x7ffff7fc0700 (LWP 31961) "foo" thread_function0 (arg=0x0) at threads.c:68
    3  Thread 0x7ffff77bf700 (LWP 31962) "bar" thread_function1 (arg=0x1) at threads.c:87
  (gdb) t 2
  [Switching to thread 2, Thread 0x7ffff7fc0700 (LWP 31961)]
  #0  thread_function0 (arg=0x0) at threads.c:68
  68              (*myp) ++;
  (gdb) catch syscall
  Catchpoint 6 (any syscall)
  (gdb) c&
  Continuing.
  (gdb)
  Thread 2 "foo" hit Catchpoint 6 (call to syscall nanosleep), 0x0000003615ebc6ed in nanosleep () at ../sysdeps/unix/syscall-template.S:81
  81      T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)

I'll work on documentation next if this looks agreeable.

This patch applies on top of the star wildcards thread IDs series:

  https://sourceware.org/ml/gdb-patches/2016-01/msg00291.html

For convenience, I've pushed this to the
users/palves/show-which-thread-caused-stop branch.

gdb/doc/ChangeLog:
2016-01-18  Pedro Alves  <palves@redhat.com>

	* gdb.texinfo (Threads): Mention that GDB displays the ID and name
	of the thread that hit a breakpoint or received a signal.

gdb/ChangeLog:
2016-01-18  Pedro Alves  <palves@redhat.com>

	* NEWS: Mention that GDB now displays the ID and name of the
	thread that hit a breakpoint or received a signal.
	* break-catch-sig.c (signal_catchpoint_print_it): Use
	maybe_print_thread_hit_breakpoint.
	* break-catch-syscall.c (print_it_catch_syscall): Likewise.
	* break-catch-throw.c (print_it_exception_catchpoint): Likewise.
	* breakpoint.c (maybe_print_thread_hit_breakpoint): New function.
	(print_it_catch_fork, print_it_catch_vfork, print_it_catch_solib)
	(print_it_catch_exec, print_it_ranged_breakpoint)
	(print_it_watchpoint, print_it_masked_watchpoint, bkpt_print_it):
	Use maybe_print_thread_hit_breakpoint.
	* breakpoint.h (maybe_print_thread_hit_breakpoint): Declare.
	* gdbthread.h (show_thread_that_caused_stop): Declare.
	* infrun.c (print_signal_received_reason): Print which thread
	received signal.
	* thread.c (show_thread_that_caused_stop): New function.

gdb/testsuite/ChangeLog:
2016-01-18  Pedro Alves  <palves@redhat.com>

	* gdb.base/async-shell.exp: Adjust expected output.
	* gdb.base/dprintf-non-stop.exp: Adjust expected output.
	* gdb.base/siginfo-thread.exp: Adjust expected output.
	* gdb.base/watchpoint-hw-hit-once.exp: Adjust expected output.
	* gdb.java/jnpe.exp: Adjust expected output.
	* gdb.threads/clone-new-thread-event.exp: Adjust expected output.
	* gdb.threads/continue-pending-status.exp: Adjust expected output.
	* gdb.threads/leader-exit.exp: Adjust expected output.
	* gdb.threads/manythreads.exp: Adjust expected output.
	* gdb.threads/pthreads.exp: Adjust expected output.
	* gdb.threads/schedlock.exp: Adjust expected output.
	* gdb.threads/siginfo-threads.exp: Adjust expected output.
	* gdb.threads/signal-command-multiple-signals-pending.exp: Adjust
	expected output.
	* gdb.threads/signal-delivered-right-thread.exp: Adjust expected
	output.
	* gdb.threads/sigthread.exp: Adjust expected output.
	* gdb.threads/watchpoint-fork.exp: Adjust expected output.
2016-01-18 15:15:18 +00:00

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# Copyright (C) 2014-2016 Free Software Foundation, Inc.
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>. */
# Test that "signal FOO" behaves correctly when we have multiple
# threads that have stopped for a signal.
if [target_info exists gdb,nosignals] {
verbose "Skipping ${testfile}.exp because of nosignals."
return -1
}
standard_testfile
if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" \
executable { debug }] != "" } {
return -1
}
# Run the test proper. SCHEDLOCK indicates which variant (around
# scheduler-locking) of the test to perform.
proc test { schedlock } {
global srcfile binfile
with_test_prefix "schedlock $schedlock" {
clean_restart ${binfile}
if ![runto_main] then {
fail "Can't run to main"
return 0
}
gdb_test "handle SIGUSR1 stop print pass"
gdb_test "handle SIGUSR2 stop print pass"
gdb_test "break all_threads_started" "Breakpoint .* at .*$srcfile.*"
# Create threads one at a time, to insure stable thread
# numbers between runs and targets.
gdb_test "break thread_function" "Breakpoint .* at .*$srcfile.*"
gdb_test "continue" "thread_function.*" "thread 2 created"
gdb_test "continue" "thread_function.*" "thread 3 created"
gdb_test "continue" "all_threads_started.*"
# Using schedlock, let the main thread queue a signal for each
# non-main thread.
gdb_test_no_output "set scheduler-locking on"
gdb_test "break all_threads_signalled" "Breakpoint .* at .*$srcfile.*"
gdb_test "continue" "all_threads_signalled.*"
gdb_test "info threads" "\\\* 1\[ \t\]+Thread.*" "thread 1 selected"
# With schedlock still enabled, let each thread report its
# signal.
gdb_test "thread 3" "Switching to thread 3.*"
gdb_test "continue" "Thread 3 .*received signal SIGUSR2.*" "stop with SIGUSR2"
gdb_test "thread 2" "Switching to thread 2.*"
gdb_test "continue" "Thread 2 .*received signal SIGUSR1.*" "stop with SIGUSR1"
gdb_test "break handler_sigusr1" "Breakpoint .* at .*$srcfile.*"
gdb_test "break handler_sigusr2" "Breakpoint .* at .*$srcfile.*"
set handler_re "Breakpoint .*, handler_sigusr. \\(sig=.*\\) at .*"
# Now test the "signal" command with either scheduler locking
# enabled or disabled.
if { $schedlock == "off" } {
# With scheduler locking off, switch to the main thread
# and issue "signal 0". "signal 0" should then warn that
# two threads have signals that will be delivered. When
# we let the command proceed, a signal should be
# delivered, and thus the corresponding breakpoint in the
# signal handler should trigger.
gdb_test_no_output "set scheduler-locking off"
gdb_test "thread 1" "Switching to thread 1.*"
set queried 0
set test "signal command queries"
gdb_test_multiple "signal 0" $test {
-re "stopped with.*stopped with.*stopped with.*Continue anyway.*y or n. $" {
fail "$test (too many threads noted)"
set queried 1
}
-re "stopped with signal SIGUSR.*\r\nContinuing .*still deliver .*Continue anyway.*y or n. $" {
pass $test
set queried 1
}
-re "Continue anyway.*y or n. $" {
fail "$test (no threads noted)"
set queried 1
}
}
# Continuing should stop in one of the signal handlers.
# Which thread runs first is not determinate.
if {$queried} {
gdb_test "y" "$handler_re" "one signal delivered"
}
# Continuing a second time should stop in the other
# handler.
with_test_prefix "second signal" {
gdb_test "continue" "$handler_re" "signal delivered"
}
} else {
# With scheduler locking on, stay with thread 2 selected,
# and try to deliver its signal explicitly. The "signal"
# command should then warn that one other thread has a
# signal that will be delivered. When we let the command
# proceed, the current thread's signal should be
# delivered, and thus the corresponding breakpoint in the
# signal handler should trigger.
gdb_test "signal SIGUSR1" \
"Breakpoint .*, handler_sigusr1 \\(sig=.*\\) at .*" \
"signal command does not query, signal delivered"
with_test_prefix "second signal" {
# The other thread had stopped for a signal too, and
# it wasn't resumed yet. Disabling schedlock and
# trying "signal 0" from the main thread should warn
# again.
gdb_test_no_output "set scheduler-locking off"
set queried 0
set test "signal command queries"
gdb_test_multiple "signal 0" $test {
-re "stopped with.*stopped with.*Continue anyway.*y or n. $" {
fail "$test (too many threads noted)"
set queried 1
}
-re "stopped with signal SIGUSR.*\r\nContinuing .*still deliver .*Continue anyway.*y or n. $" {
pass $test
set queried 1
}
-re "Continue anyway.*y or n. $" {
fail "$test (no threads noted)"
set queried 1
}
}
if {$queried} {
gdb_test "y" "Breakpoint .*, handler_sigusr2 \\(sig=.*\\) at .*" "signal delivered"
}
}
}
# Both threads got their signal. Continuing again should
# neither intercept nor deliver any other signal.
gdb_test "b end" "Breakpoint .* at .*$srcfile.*"
gdb_test "continue" "end .*" "no more signals"
}
}
foreach schedlock {"off" "on"} {
test $schedlock
}