testsuite/gdb.threads/non-stop-fair-events.exp

# Copyright (C) 2014-2019 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 GDB in non-stop mode gives roughly equal priority to
# events of all threads.

standard_testfile
set executable ${testfile}

if [target_info exists gdb,nosignals] {
    verbose "Skipping ${testfile}.exp because of nosignals."
    return -1
}

set options { "additional_flags=-DTIMEOUT=$timeout" debug pthreads }
if {[prepare_for_testing "failed to prepare" $testfile $srcfile $options] == -1} {
    return -1
}

gdb_test_no_output "set non-stop on"

if ![runto_main] {
    return -1
}

# We want "handle print", to make sure the target backend reports the
# signal to the run control core.
gdb_test "handle SIGUSR1 print nostop pass" ""

# Get current value of VAR from the inferior.  TEST is used as test
# message.

proc get_value {var test} {
    global expect_out
    global gdb_prompt
    global decimal

    set value -1
    gdb_test_multiple "print $var" "$test" {
	-re ".*= ($decimal).*\r\n$gdb_prompt $" {
	    set value $expect_out(1,string)
	    pass "$test"
        }
    }
    return ${value}
}

set NUM_THREADS [get_value "num_threads" "get num_threads"]

# Account for the main thread.
incr NUM_THREADS

# Probe for displaced stepping support.  We're stopped at the main
# breakpoint.  If displaced stepping is supported, we should see
# related debug output.
set displaced_stepping_enabled 0
set msg "check displaced-stepping"
gdb_test_no_output "set debug displaced 1"
gdb_test_multiple "next" $msg {
    -re "displaced pc to.*$gdb_prompt $" {
	set displaced_stepping_enabled 1
    }
    -re ".*$gdb_prompt $" {
    }
}
gdb_test_no_output "set debug displaced 0"

# Run threads to their start positions.  This prepares for a new test
# sequence.

proc restart {} {
    global gdb_prompt
    global NUM_THREADS

    delete_breakpoints

    gdb_test "print got_sig = 0" " = 0"

    gdb_breakpoint [gdb_get_line_number "set thread breakpoint here"]
    gdb_breakpoint [gdb_get_line_number "set kill breakpoint here"]

    set test "continue -a&"
    gdb_test_multiple $test $test {
	-re "Continuing.\r\n$gdb_prompt " {
	    pass $test
	}
    }

    for {set i 1} { $i <= $NUM_THREADS } { incr i } {
	set test "thread $i restarted"
	gdb_test_multiple "" $test {
	    -re "breakpoint here" {
		# The prompt was already matched in the "continue &"
		# test above.  We're now consuming asynchronous output
		# that comes after the prompt.
		pass $test
	    }
	}
    }

    delete_breakpoints
}

# Run command and wait for the prompt, without end anchor.

proc gdb_test_no_anchor {cmd} {
    global gdb_prompt

    gdb_test_multiple $cmd $cmd {
	-re "$gdb_prompt " {
	    pass $cmd
	}
    }
}

# Enable/disable debugging.

proc enable_debug {enable} {

    # Comment out to debug problems with the test.
    return

    gdb_test_no_anchor "set debug infrun $enable"
    gdb_test_no_anchor "set debug displaced $enable"
}

# The test proper.  SIGNAL_THREAD is the thread that has been elected
# to receive the SIGUSR1 signal.

proc test {signal_thread} {
    global gdb_prompt
    global NUM_THREADS
    global timeout
    global displaced_stepping_enabled

    with_test_prefix "signal_thread=$signal_thread" {
	restart

	# Set all threads stepping the infinite loop line in parallel.
	for {set i 2} { $i <= $NUM_THREADS } { incr i } {
	    gdb_test "thread $i" \
		"child_function.*set thread breakpoint here.*" \
		"switch to thread $i to step it"

	    if {$i == $signal_thread} {
		gdb_test "print signal_thread = self" " = .*"
	    }

	    gdb_test "step&" "" "set $i thread stepping"
	}

	gdb_test "thread 1" "Switching to .*" \
	    "switch to the main thread to queue signal"

	# Let the main thread queue the signal.
	gdb_breakpoint "loop_broke"

	enable_debug 1

	# On software single-step targets that don't support displaced
	# stepping, threads keep hitting each others' single-step
	# breakpoints, and then GDB needs to pause all threads to step
	# past those.  The end result is that progress in the main
	# thread will be slower and it may take a bit longer for the
	# signal to be queued; bump the timeout.
	if {!$displaced_stepping_enabled && ![can_hardware_single_step]} {
	    # The more threads we have, the longer it takes.
	    set factor $NUM_THREADS
	} else {
	    set factor 1
	}
	with_timeout_factor $factor {
	    gdb_test "print timeout = $timeout" " = $timeout" \
		"set timeout in the inferior"

	    set saw_continuing 0
	    set test "continue &"
	    gdb_test_multiple $test $test {
		-re "Continuing.\r\n" {
		    set saw_continuing 1
		    exp_continue
		}
		-re "$gdb_prompt " {
		    gdb_assert $saw_continuing $test
		}
		-re "infrun:" {
		    exp_continue
		}
	    }

	    set gotit 0

	    # Wait for all threads to finish their steps, and for the main
	    # thread to hit the breakpoint.
	    for {set i 1} { $i <= $NUM_THREADS } { incr i } {
		set test "thread $i broke out of loop"
		set gotit 0
		gdb_test_multiple "" $test {
		    -re "loop_broke" {
			# The prompt was already matched in the "continue
			# &" test above.  We're now consuming asynchronous
			# output that comes after the prompt.
			set gotit 1
			pass $test
		    }
		    -re "infrun:" {
			exp_continue
		    }
		}
		if {!$gotit} {
		    break
		}
	    }
	}

	enable_debug 0

	# It's helpful to have this in the log if the test ever
	# happens to fail.
	gdb_test "info threads"

	return $gotit
    }
}

# The kernel/debug API may always walk its thread list looking for the
# first with an event, resulting in giving priority to e.g. the thread
# with lowest kernel thread ID.  So test once with the signal pending
# in each thread, except the main thread.
for {set i 2} { $i <= $NUM_THREADS } { incr i } {
    if {![test $i]} {
	# Avoid cascading timeouts, and bail out.
	return
    }
}