scftorture: Count single_rpc offline failures in statistics outputgrafted

scf_torture_stats_print() aggregates each invoker thread's counters
into a local scf_statistics structure before printing, but the
n_single_rpc_ofl field is missing from the aggregation loop.  As a
result, the "single_rpc_ofl" value printed in the statistics line is
always zero, even when smp_call_function_single() invocations for the
RPC test have failed due to offline CPUs and been counted by the
invoker threads.

Add the missing accumulation so that the printed value reflects the
actual counts.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

1 files changed, 324 insertions, 0 deletions

diff --git a/io_uring/wait.c b/io_uring/wait.c
new file mode 100644
index 000000000..a48523c2f
--- /dev/null
+++ b/io_uring/wait.c
@@ -0,0 +1,324 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Waiting for completion events
+ */
+#include <linux/kernel.h>
+#include <linux/sched/signal.h>
+#include <linux/io_uring.h>
+#include <linux/time_namespace.h>
+
+#include <trace/events/io_uring.h>
+
+#include <uapi/linux/io_uring.h>
+
+#include "io_uring.h"
+#include "napi.h"
+#include "wait.h"
+
+static int io_wake_function(struct wait_queue_entry *curr, unsigned int mode,
+			    int wake_flags, void *key)
+{
+	struct io_wait_queue *iowq = container_of(curr, struct io_wait_queue, wq);
+
+	/*
+	 * Cannot safely flush overflowed CQEs from here, ensure we wake up
+	 * the task, and the next invocation will do it.
+	 */
+	if (io_should_wake(iowq) || io_has_work(iowq->ctx))
+		return autoremove_wake_function(curr, mode, wake_flags, key);
+	return -1;
+}
+
+int io_run_task_work_sig(struct io_ring_ctx *ctx)
+{
+	if (io_local_work_pending(ctx)) {
+		__set_current_state(TASK_RUNNING);
+		if (io_run_local_work(ctx, INT_MAX, IO_LOCAL_TW_DEFAULT_MAX) > 0)
+			return 0;
+	}
+	if (io_run_task_work() > 0)
+		return 0;
+	if (task_sigpending(current))
+		return -EINTR;
+	return 0;
+}
+
+static bool current_pending_io(void)
+{
+	struct io_uring_task *tctx = current->io_uring;
+
+	if (!tctx)
+		return false;
+	return percpu_counter_read_positive(&tctx->inflight);
+}
+
+static enum hrtimer_restart io_cqring_timer_wakeup(struct hrtimer *timer)
+{
+	struct io_wait_queue *iowq = container_of(timer, struct io_wait_queue, t);
+
+	WRITE_ONCE(iowq->hit_timeout, 1);
+	iowq->min_timeout = 0;
+	wake_up_process(iowq->wq.private);
+	return HRTIMER_NORESTART;
+}
+
+/*
+ * Doing min_timeout portion. If we saw any timeouts, events, or have work,
+ * wake up. If not, and we have a normal timeout, switch to that and keep
+ * sleeping.
+ */
+static enum hrtimer_restart io_cqring_min_timer_wakeup(struct hrtimer *timer)
+{
+	struct io_wait_queue *iowq = container_of(timer, struct io_wait_queue, t);
+	struct io_ring_ctx *ctx = iowq->ctx;
+
+	/* no general timeout, or shorter (or equal), we are done */
+	if (iowq->timeout == KTIME_MAX ||
+	    ktime_compare(iowq->min_timeout, iowq->timeout) >= 0)
+		goto out_wake;
+	/* work we may need to run, wake function will see if we need to wake */
+	if (io_has_work(ctx))
+		goto out_wake;
+	/* got events since we started waiting, min timeout is done */
+	scoped_guard(rcu) {
+		struct io_rings *rings = io_get_rings(ctx);
+
+		if (iowq->cq_min_tail != READ_ONCE(rings->cq.tail))
+			goto out_wake;
+		/* if we have any events and min timeout expired, we're done */
+		if (io_cqring_events(ctx))
+			goto out_wake;
+	}
+	/*
+	 * If using deferred task_work running and application is waiting on
+	 * more than one request, ensure we reset it now where we are switching
+	 * to normal sleeps. Any request completion post min_wait should wake
+	 * the task and return.
+	 */
+	if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
+		atomic_set(&ctx->cq_wait_nr, 1);
+		smp_mb();
+		if (io_local_work_pending(ctx))
+			goto out_wake;
+	}
+
+	/* any generated CQE posted past this time should wake us up */
+	iowq->cq_tail = iowq->cq_min_tail + 1;
+
+	hrtimer_update_function(&iowq->t, io_cqring_timer_wakeup);
+	hrtimer_set_expires(timer, iowq->timeout);
+	return HRTIMER_RESTART;
+out_wake:
+	return io_cqring_timer_wakeup(timer);
+}
+
+static int io_cqring_schedule_timeout(struct io_wait_queue *iowq,
+				      clockid_t clock_id, ktime_t start_time)
+{
+	ktime_t timeout;
+
+	if (iowq->min_timeout) {
+		timeout = ktime_add_ns(iowq->min_timeout, start_time);
+		hrtimer_setup_on_stack(&iowq->t, io_cqring_min_timer_wakeup, clock_id,
+				       HRTIMER_MODE_ABS);
+	} else {
+		timeout = iowq->timeout;
+		hrtimer_setup_on_stack(&iowq->t, io_cqring_timer_wakeup, clock_id,
+				       HRTIMER_MODE_ABS);
+	}
+
+	hrtimer_set_expires_range_ns(&iowq->t, timeout, 0);
+	hrtimer_start_expires(&iowq->t, HRTIMER_MODE_ABS);
+
+	if (!READ_ONCE(iowq->hit_timeout))
+		schedule();
+
+	hrtimer_cancel(&iowq->t);
+	destroy_hrtimer_on_stack(&iowq->t);
+	__set_current_state(TASK_RUNNING);
+
+	return READ_ONCE(iowq->hit_timeout) ? -ETIME : 0;
+}
+
+static int __io_cqring_wait_schedule(struct io_ring_ctx *ctx,
+				     struct io_wait_queue *iowq,
+				     struct ext_arg *ext_arg,
+				     ktime_t start_time)
+{
+	int ret = 0;
+
+	/*
+	 * Mark us as being in io_wait if we have pending requests, so cpufreq
+	 * can take into account that the task is waiting for IO - turns out
+	 * to be important for low QD IO.
+	 */
+	if (ext_arg->iowait && current_pending_io())
+		current->in_iowait = 1;
+	if (iowq->timeout != KTIME_MAX || iowq->min_timeout)
+		ret = io_cqring_schedule_timeout(iowq, ctx->clockid, start_time);
+	else
+		schedule();
+	current->in_iowait = 0;
+	return ret;
+}
+
+/* If this returns > 0, the caller should retry */
+static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
+					  struct io_wait_queue *iowq,
+					  struct ext_arg *ext_arg,
+					  ktime_t start_time)
+{
+	if (unlikely(READ_ONCE(ctx->check_cq)))
+		return 1;
+	if (unlikely(io_local_work_pending(ctx)))
+		return 1;
+	if (unlikely(task_work_pending(current)))
+		return 1;
+	if (unlikely(task_sigpending(current)))
+		return -EINTR;
+	if (unlikely(io_should_wake(iowq)))
+		return 0;
+
+	return __io_cqring_wait_schedule(ctx, iowq, ext_arg, start_time);
+}
+
+/*
+ * Wait until events become available, if we don't already have some. The
+ * application must reap them itself, as they reside on the shared cq ring.
+ */
+int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, u32 flags,
+		   struct ext_arg *ext_arg)
+{
+	struct io_wait_queue iowq;
+	struct io_rings *rings;
+	ktime_t start_time;
+	int ret, nr_wait;
+
+	min_events = min_t(int, min_events, ctx->cq_entries);
+
+	if (!io_allowed_run_tw(ctx))
+		return -EEXIST;
+	if (io_local_work_pending(ctx))
+		io_run_local_work(ctx, min_events,
+				  max(IO_LOCAL_TW_DEFAULT_MAX, min_events));
+	io_run_task_work();
+
+	if (unlikely(test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq)))
+		io_cqring_do_overflow_flush(ctx);
+
+	rcu_read_lock();
+	rings = io_get_rings(ctx);
+	if (__io_cqring_events_user(ctx) >= min_events) {
+		rcu_read_unlock();
+		return 0;
+	}
+
+	init_waitqueue_func_entry(&iowq.wq, io_wake_function);
+	iowq.wq.private = current;
+	INIT_LIST_HEAD(&iowq.wq.entry);
+	iowq.ctx = ctx;
+	iowq.cq_tail = READ_ONCE(rings->cq.head) + min_events;
+	iowq.cq_min_tail = READ_ONCE(rings->cq.tail);
+	nr_wait = (int) iowq.cq_tail - READ_ONCE(rings->cq.tail);
+	rcu_read_unlock();
+	rings = NULL;
+	iowq.nr_timeouts = atomic_read(&ctx->cq_timeouts);
+	iowq.hit_timeout = 0;
+	iowq.min_timeout = ext_arg->min_time;
+	iowq.timeout = KTIME_MAX;
+	start_time = io_get_time(ctx);
+
+	if (ext_arg->ts_set) {
+		iowq.timeout = timespec64_to_ktime(ext_arg->ts);
+		if (flags & IORING_ENTER_ABS_TIMER)
+			iowq.timeout = timens_ktime_to_host(ctx->clockid,
+							    iowq.timeout);
+		else
+			iowq.timeout = ktime_add(iowq.timeout, start_time);
+	}
+
+	if (ext_arg->sig) {
+#ifdef CONFIG_COMPAT
+		if (in_compat_syscall())
+			ret = set_compat_user_sigmask((const compat_sigset_t __user *)ext_arg->sig,
+						      ext_arg->argsz);
+		else
+#endif
+			ret = set_user_sigmask(ext_arg->sig, ext_arg->argsz);
+
+		if (ret)
+			return ret;
+	}
+
+	io_napi_busy_loop(ctx, &iowq);
+
+	trace_io_uring_cqring_wait(ctx, min_events);
+	do {
+		unsigned long check_cq;
+
+		if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
+			atomic_set(&ctx->cq_wait_nr, nr_wait);
+			set_current_state(TASK_INTERRUPTIBLE);
+		} else {
+			prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq,
+							TASK_INTERRUPTIBLE);
+		}
+
+		ret = io_cqring_wait_schedule(ctx, &iowq, ext_arg, start_time);
+		__set_current_state(TASK_RUNNING);
+		atomic_set(&ctx->cq_wait_nr, IO_CQ_WAKE_INIT);
+
+		/*
+		 * Run task_work after scheduling and before io_should_wake().
+		 * If we got woken because of task_work being processed, run it
+		 * now rather than let the caller do another wait loop.
+		 */
+		if (io_local_work_pending(ctx))
+			io_run_local_work(ctx, nr_wait, nr_wait);
+		io_run_task_work();
+
+		/*
+		 * Non-local task_work will be run on exit to userspace, but
+		 * if we're using DEFER_TASKRUN, then we could have waited
+		 * with a timeout for a number of requests. If the timeout
+		 * hits, we could have some requests ready to process. Ensure
+		 * this break is _after_ we have run task_work, to avoid
+		 * deferring running potentially pending requests until the
+		 * next time we wait for events.
+		 */
+		if (ret < 0)
+			break;
+
+		check_cq = READ_ONCE(ctx->check_cq);
+		if (unlikely(check_cq)) {
+			/* let the caller flush overflows, retry */
+			if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT))
+				io_cqring_do_overflow_flush(ctx);
+			if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT)) {
+				ret = -EBADR;
+				break;
+			}
+		}
+
+		if (io_should_wake(&iowq)) {
+			ret = 0;
+			break;
+		}
+		cond_resched();
+
+		/* if min timeout has been hit, don't reset wait count */
+		if (!iowq.hit_timeout)
+			scoped_guard(rcu)
+				nr_wait = (int) iowq.cq_tail -
+						READ_ONCE(io_get_rings(ctx)->cq.tail);
+		else
+			nr_wait = 1;
+	} while (1);
+
+	if (!(ctx->flags & IORING_SETUP_DEFER_TASKRUN))
+		finish_wait(&ctx->cq_wait, &iowq.wq);
+	restore_saved_sigmask_unless(ret == -EINTR);
+
+	guard(rcu)();
+	return READ_ONCE(io_get_rings(ctx)->cq.head) == READ_ONCE(io_get_rings(ctx)->cq.tail) ? ret : 0;
+}