[gdb/testsuite] Fix gdb.base/bg-exec-sigint-bp-cond.exp for signal merging

The test-case gdb.base/bg-exec-sigint-bp-cond.exp sends 10 SIGINTS to gdb, and
counts whether 10 have arrived.

Occasionally, less than 10 arrive due to signal merging [1].

This is more likely to happen when building gdb with -fsanitize=thread.

Fix this by instead, sending one SIGINT at a time, and waiting for it to
arrive.

This still makes the test-case fail if the fix fixing the PR that the
test-case was introduced for is reverted.

Tested on aarch64-linux and x86_64-linux.

PR testsuite/32329
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32329

[1] https://www.gnu.org/software/libc/manual/html_node/Merged-Signals.html

1 files changed, 36 insertions, 25 deletions

diff --git a/gdb/testsuite/gdb.base/bg-exec-sigint-bp-cond.exp b/gdb/testsuite/gdb.base/bg-exec-sigint-bp-cond.exp
index ce2231d..7168a73 100644
--- a/gdb/testsuite/gdb.base/bg-exec-sigint-bp-cond.exp
+++ b/gdb/testsuite/gdb.base/bg-exec-sigint-bp-cond.exp
@@ -40,39 +40,50 @@ proc test { {after_kill_cond ""} } {
 
     set gdb_pid [exp_pid -i [board_info host fileid]]
 
-    # Number of times the breakpoint should be hit before stopping.
-    set num_hits 10
-
-    # A counter used in the breakpoint's condition to ensure that it
-    # causes a stop after NUM_HITS hits.
-    gdb_test "p \$hit_count = 0" " = 0" "reset hit counter"
-
     # Set a breakpoint with a condition that sends a SIGINT to GDB.  This
     # emulates pressing Ctrl-C just while GDB is evaluating the breakpoint
     # condition.
     gdb_test \
-	"break foo if \$hit_count\+\+ == $num_hits || \$_shell(\"kill -INT $gdb_pid\") != 0 $after_kill_cond" \
+	"break foo if \$hit_count\+\+ == 1 || \$_shell(\"kill -INT $gdb_pid\") != 0 $after_kill_cond" \
 	"Breakpoint .*" \
 	"break foo if <condition>"
 
-    # Number of times we've seen GDB print "Quit" followed by the
-    # prompt.  We should see that exactly $NUM_HITS times.
-    set quit_count 0
+    for { set i 0 } { $i < 10 } { incr i } {
+	set done 0
+	with_test_prefix $i {
 
-    gdb_test_multiple "c&" "SIGINT does not interrupt background execution" {
-	-re "^c&\r\nContinuing\\.\r\n$::gdb_prompt " {
-	    exp_continue
-	}
-	-re "^Quit\r\n$::gdb_prompt " {
-	    incr quit_count
-	    verbose -log "quit_count=$quit_count"
-	    exp_continue
-	}
-	-re "^\r\nBreakpoint .*return 0;" {
-	    gdb_assert {$quit_count == $num_hits} $gdb_test_name
-	}
-	-re ".*Asynchronous execution not supported on this target\..*" {
-	    unsupported "$gdb_test_name (asynchronous execution not supported)"
+	    # A counter used in the breakpoint's condition to ensure that it
+	    # causes a stop after one hit.
+	    gdb_test "p \$hit_count = 0" " = 0" "reset hit counter"
+
+	    # Number of times we've seen GDB print "Quit" followed by the
+	    # prompt.  We should see that exactly one time.
+	    set quit_count 0
+
+	    gdb_test_multiple "c&" "SIGINT does not interrupt background execution" {
+		-re "^c&\r\nContinuing\\.\r\n$::gdb_prompt " {
+		    exp_continue
+		}
+		-re "^Quit\r\n$::gdb_prompt " {
+		    incr quit_count
+		    verbose -log "quit_count=$quit_count"
+		    exp_continue
+		}
+		-re "^\r\nBreakpoint .*return 0;" {
+		    gdb_assert {$quit_count == 1} $gdb_test_name
+		}
+		-re ".*Asynchronous execution not supported on this target\..*" {
+		    unsupported "$gdb_test_name (asynchronous execution not supported)"
+		}
+		timeout {
+		    set done 1
+		    fail "$gdb_test_name (timeout)"
+		}
+	    }
+
+	    if { $done } {
+		break
+	    }
 	}
     }
 }