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, 55 insertions, 0 deletions

diff --git a/io_uring/wait.h b/io_uring/wait.h
new file mode 100644
index 000000000..b7b9c46b1
--- /dev/null
+++ b/io_uring/wait.h
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef IOU_WAIT_H
+#define IOU_WAIT_H
+
+#include <linux/io_uring_types.h>
+
+/*
+ * ->cq_wait_nr is armed with the number of lazy task_work adds the waiter
+ * still needs, and counted down by the add side, with the add reaching zero
+ * issuing the (single) wake up for this wait cycle. Zero and below means no
+ * wake up is to be issued: IO_CQ_WAKE_INIT when no task is waiting (also
+ * what a forced wake up resets it to when claiming one), zero once the
+ * countdown has fired.
+ */
+#define IO_CQ_WAKE_INIT		(-1)
+
+struct ext_arg {
+	size_t argsz;
+	struct timespec64 ts;
+	const sigset_t __user *sig;
+	ktime_t min_time;
+	bool ts_set;
+	bool iowait;
+};
+
+int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, u32 flags,
+		   struct ext_arg *ext_arg);
+int io_run_task_work_sig(struct io_ring_ctx *ctx);
+void io_cqring_do_overflow_flush(struct io_ring_ctx *ctx);
+void io_cqring_overflow_flush_locked(struct io_ring_ctx *ctx);
+
+static inline unsigned int __io_cqring_events(struct io_ring_ctx *ctx)
+{
+	struct io_rings *rings = io_get_rings(ctx);
+	return ctx->cached_cq_tail - READ_ONCE(rings->cq.head);
+}
+
+static inline unsigned int __io_cqring_events_user(struct io_ring_ctx *ctx)
+{
+	struct io_rings *rings = io_get_rings(ctx);
+
+	return READ_ONCE(rings->cq.tail) - READ_ONCE(rings->cq.head);
+}
+
+/*
+ * Reads the tail/head of the CQ ring while providing an acquire ordering,
+ * see comment at top of io_uring.c.
+ */
+static inline unsigned io_cqring_events(struct io_ring_ctx *ctx)
+{
+	smp_rmb();
+	return __io_cqring_events(ctx);
+}
+
+#endif