selftests/bpf: Add a test for objects stuck in free_by_rcu_ttracegrafted

Delete all elements of BPF_F_NO_PREALLOC hash map in one batch. The first
free_bulk() starts RCU tasks trace GP and the rest of the elements are
freed while it's in flight. Wait for call_rcu_ttrace_in_progress to clear
in bpf_mem_cache of every cpu and check that free_by_rcu_ttrace and
waiting_for_gp_ttrace lists are empty.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20260930095920.601738-4-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/lib/bust_spinlocks.c b/lib/bust_spinlocks.c
new file mode 100644
index 000000000..bfd53972a
--- /dev/null
+++ b/lib/bust_spinlocks.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * lib/bust_spinlocks.c
+ *
+ * Provides a minimal bust_spinlocks for architectures which don't
+ * have one of their own.
+ *
+ * bust_spinlocks() clears any spinlocks which would prevent oops, die(), BUG()
+ * and panic() information from reaching the user.
+ */
+
+#include <linux/kernel.h>
+#include <linux/printk.h>
+#include <linux/spinlock.h>
+#include <linux/tty.h>
+#include <linux/wait.h>
+#include <linux/vt_kern.h>
+#include <linux/console.h>
+
+void bust_spinlocks(int yes)
+{
+	if (yes) {
+		++oops_in_progress;
+	} else {
+		console_unblank();
+		if (--oops_in_progress == 0)
+			wake_up_klogd();
+	}
+}