Add cross-link

1 files changed, 436 insertions, 0 deletions

diff --git a/contrib/libs/liburing/src/queue.c b/contrib/libs/liburing/src/queue.c
new file mode 100644
index 0000000000..4b4220782d
--- /dev/null
+++ b/contrib/libs/liburing/src/queue.c
@@ -0,0 +1,436 @@
+#include "../config-host.h"
+/* SPDX-License-Identifier: MIT */
+#define _POSIX_C_SOURCE 200112L
+
+#include "lib.h"
+#include "syscall.h"
+#include "liburing.h"
+#include "int_flags.h"
+#include "liburing/compat.h"
+#include "liburing/io_uring.h"
+
+/*
+ * Returns true if we're not using SQ thread (thus nobody submits but us)
+ * or if IORING_SQ_NEED_WAKEUP is set, so submit thread must be explicitly
+ * awakened. For the latter case, we set the thread wakeup flag.
+ * If no SQEs are ready for submission, returns false.
+ */
+static inline bool sq_ring_needs_enter(struct io_uring *ring,
+				       unsigned submit,
+				       unsigned *flags)
+{
+	if (!submit)
+		return false;
+
+	if (!(ring->flags & IORING_SETUP_SQPOLL))
+		return true;
+
+	/*
+	 * Ensure the kernel can see the store to the SQ tail before we read
+	 * the flags.
+	 */
+	io_uring_smp_mb();
+
+	if (uring_unlikely(IO_URING_READ_ONCE(*ring->sq.kflags) &
+			   IORING_SQ_NEED_WAKEUP)) {
+		*flags |= IORING_ENTER_SQ_WAKEUP;
+		return true;
+	}
+
+	return false;
+}
+
+static inline bool cq_ring_needs_flush(struct io_uring *ring)
+{
+	return IO_URING_READ_ONCE(*ring->sq.kflags) &
+				 (IORING_SQ_CQ_OVERFLOW | IORING_SQ_TASKRUN);
+}
+
+static inline bool cq_ring_needs_enter(struct io_uring *ring)
+{
+	return (ring->flags & IORING_SETUP_IOPOLL) || cq_ring_needs_flush(ring);
+}
+
+struct get_data {
+	unsigned submit;
+	unsigned wait_nr;
+	unsigned get_flags;
+	int sz;
+	int has_ts;
+	void *arg;
+};
+
+static int _io_uring_get_cqe(struct io_uring *ring,
+			     struct io_uring_cqe **cqe_ptr,
+			     struct get_data *data)
+{
+	struct io_uring_cqe *cqe = NULL;
+	bool looped = false;
+	int err = 0;
+
+	do {
+		bool need_enter = false;
+		unsigned flags = 0;
+		unsigned nr_available;
+		int ret;
+
+		ret = __io_uring_peek_cqe(ring, &cqe, &nr_available);
+		if (ret) {
+			if (!err)
+				err = ret;
+			break;
+		}
+		if (!cqe && !data->wait_nr && !data->submit) {
+			/*
+			 * If we already looped once, we already entererd
+			 * the kernel. Since there's nothing to submit or
+			 * wait for, don't keep retrying.
+			 */
+			if (looped || !cq_ring_needs_enter(ring)) {
+				if (!err)
+					err = -EAGAIN;
+				break;
+			}
+			need_enter = true;
+		}
+		if (data->wait_nr > nr_available || need_enter) {
+			flags = IORING_ENTER_GETEVENTS | data->get_flags;
+			need_enter = true;
+		}
+		if (sq_ring_needs_enter(ring, data->submit, &flags))
+			need_enter = true;
+		if (!need_enter)
+			break;
+		if (looped && data->has_ts) {
+			struct io_uring_getevents_arg *arg = data->arg;
+
+			if (!cqe && arg->ts && !err)
+				err = -ETIME;
+			break;
+		}
+
+		if (ring->int_flags & INT_FLAG_REG_RING)
+			flags |= IORING_ENTER_REGISTERED_RING;
+		ret = __sys_io_uring_enter2(ring->enter_ring_fd, data->submit,
+					    data->wait_nr, flags, data->arg,
+					    data->sz);
+		if (ret < 0) {
+			if (!err)
+				err = ret;
+			break;
+		}
+
+		data->submit -= ret;
+		if (cqe)
+			break;
+		if (!looped) {
+			looped = true;
+			err = ret;
+		}
+	} while (1);
+
+	*cqe_ptr = cqe;
+	return err;
+}
+
+int __io_uring_get_cqe(struct io_uring *ring, struct io_uring_cqe **cqe_ptr,
+		       unsigned submit, unsigned wait_nr, sigset_t *sigmask)
+{
+	struct get_data data = {
+		.submit		= submit,
+		.wait_nr 	= wait_nr,
+		.get_flags	= 0,
+		.sz		= _NSIG / 8,
+		.arg		= sigmask,
+	};
+
+	return _io_uring_get_cqe(ring, cqe_ptr, &data);
+}
+
+int io_uring_get_events(struct io_uring *ring)
+{
+	int flags = IORING_ENTER_GETEVENTS;
+
+	if (ring->int_flags & INT_FLAG_REG_RING)
+		flags |= IORING_ENTER_REGISTERED_RING;
+	return __sys_io_uring_enter(ring->enter_ring_fd, 0, 0, flags, NULL);
+}
+
+/*
+ * Fill in an array of IO completions up to count, if any are available.
+ * Returns the amount of IO completions filled.
+ */
+unsigned io_uring_peek_batch_cqe(struct io_uring *ring,
+				 struct io_uring_cqe **cqes, unsigned count)
+{
+	unsigned ready;
+	bool overflow_checked = false;
+	int shift = 0;
+
+	if (ring->flags & IORING_SETUP_CQE32)
+		shift = 1;
+
+again:
+	ready = io_uring_cq_ready(ring);
+	if (ready) {
+		unsigned head = *ring->cq.khead;
+		unsigned mask = ring->cq.ring_mask;
+		unsigned last;
+		int i = 0;
+
+		count = count > ready ? ready : count;
+		last = head + count;
+		for (;head != last; head++, i++)
+			cqes[i] = &ring->cq.cqes[(head & mask) << shift];
+
+		return count;
+	}
+
+	if (overflow_checked)
+		return 0;
+
+	if (cq_ring_needs_flush(ring)) {
+		io_uring_get_events(ring);
+		overflow_checked = true;
+		goto again;
+	}
+
+	return 0;
+}
+
+/*
+ * Sync internal state with kernel ring state on the SQ side. Returns the
+ * number of pending items in the SQ ring, for the shared ring.
+ */
+unsigned __io_uring_flush_sq(struct io_uring *ring)
+{
+	struct io_uring_sq *sq = &ring->sq;
+	unsigned tail = sq->sqe_tail;
+
+	if (sq->sqe_head != tail) {
+		sq->sqe_head = tail;
+		/*
+		 * Ensure kernel sees the SQE updates before the tail update.
+		 */
+		if (!(ring->flags & IORING_SETUP_SQPOLL))
+			IO_URING_WRITE_ONCE(*sq->ktail, tail);
+		else
+			io_uring_smp_store_release(sq->ktail, tail);
+	}
+	/*
+	 * This _may_ look problematic, as we're not supposed to be reading
+	 * SQ->head without acquire semantics. When we're in SQPOLL mode, the
+	 * kernel submitter could be updating this right now. For non-SQPOLL,
+	 * task itself does it, and there's no potential race. But even for
+	 * SQPOLL, the load is going to be potentially out-of-date the very
+	 * instant it's done, regardless or whether or not it's done
+	 * atomically. Worst case, we're going to be over-estimating what
+	 * we can submit. The point is, we need to be able to deal with this
+	 * situation regardless of any perceived atomicity.
+	 */
+	return tail - *sq->khead;
+}
+
+/*
+ * If we have kernel support for IORING_ENTER_EXT_ARG, then we can use that
+ * more efficiently than queueing an internal timeout command.
+ */
+static int io_uring_wait_cqes_new(struct io_uring *ring,
+				  struct io_uring_cqe **cqe_ptr,
+				  unsigned wait_nr,
+				  struct __kernel_timespec *ts,
+				  sigset_t *sigmask)
+{
+	struct io_uring_getevents_arg arg = {
+		.sigmask	= (unsigned long) sigmask,
+		.sigmask_sz	= _NSIG / 8,
+		.ts		= (unsigned long) ts
+	};
+	struct get_data data = {
+		.wait_nr	= wait_nr,
+		.get_flags	= IORING_ENTER_EXT_ARG,
+		.sz		= sizeof(arg),
+		.has_ts		= ts != NULL,
+		.arg		= &arg
+	};
+
+	return _io_uring_get_cqe(ring, cqe_ptr, &data);
+}
+
+/*
+ * Like io_uring_wait_cqe(), except it accepts a timeout value as well. Note
+ * that an sqe is used internally to handle the timeout. For kernel doesn't
+ * support IORING_FEAT_EXT_ARG, applications using this function must never
+ * set sqe->user_data to LIBURING_UDATA_TIMEOUT!
+ *
+ * For kernels without IORING_FEAT_EXT_ARG (5.10 and older), if 'ts' is
+ * specified, the application need not call io_uring_submit() before
+ * calling this function, as we will do that on its behalf. From this it also
+ * follows that this function isn't safe to use for applications that split SQ
+ * and CQ handling between two threads and expect that to work without
+ * synchronization, as this function manipulates both the SQ and CQ side.
+ *
+ * For kernels with IORING_FEAT_EXT_ARG, no implicit submission is done and
+ * hence this function is safe to use for applications that split SQ and CQ
+ * handling between two threads.
+ */
+static int __io_uring_submit_timeout(struct io_uring *ring, unsigned wait_nr,
+				     struct __kernel_timespec *ts)
+{
+	struct io_uring_sqe *sqe;
+	int ret;
+
+	/*
+	 * If the SQ ring is full, we may need to submit IO first
+	 */
+	sqe = io_uring_get_sqe(ring);
+	if (!sqe) {
+		ret = io_uring_submit(ring);
+		if (ret < 0)
+			return ret;
+		sqe = io_uring_get_sqe(ring);
+		if (!sqe)
+			return -EAGAIN;
+	}
+	io_uring_prep_timeout(sqe, ts, wait_nr, 0);
+	sqe->user_data = LIBURING_UDATA_TIMEOUT;
+	return __io_uring_flush_sq(ring);
+}
+
+int io_uring_wait_cqes(struct io_uring *ring, struct io_uring_cqe **cqe_ptr,
+		       unsigned wait_nr, struct __kernel_timespec *ts,
+		       sigset_t *sigmask)
+{
+	int to_submit = 0;
+
+	if (ts) {
+		if (ring->features & IORING_FEAT_EXT_ARG)
+			return io_uring_wait_cqes_new(ring, cqe_ptr, wait_nr,
+							ts, sigmask);
+		to_submit = __io_uring_submit_timeout(ring, wait_nr, ts);
+		if (to_submit < 0)
+			return to_submit;
+	}
+
+	return __io_uring_get_cqe(ring, cqe_ptr, to_submit, wait_nr, sigmask);
+}
+
+int io_uring_submit_and_wait_timeout(struct io_uring *ring,
+				     struct io_uring_cqe **cqe_ptr,
+				     unsigned wait_nr,
+				     struct __kernel_timespec *ts,
+				     sigset_t *sigmask)
+{
+	int to_submit;
+
+	if (ts) {
+		if (ring->features & IORING_FEAT_EXT_ARG) {
+			struct io_uring_getevents_arg arg = {
+				.sigmask	= (unsigned long) sigmask,
+				.sigmask_sz	= _NSIG / 8,
+				.ts		= (unsigned long) ts
+			};
+			struct get_data data = {
+				.submit		= __io_uring_flush_sq(ring),
+				.wait_nr	= wait_nr,
+				.get_flags	= IORING_ENTER_EXT_ARG,
+				.sz		= sizeof(arg),
+				.has_ts		= ts != NULL,
+				.arg		= &arg
+			};
+
+			return _io_uring_get_cqe(ring, cqe_ptr, &data);
+		}
+		to_submit = __io_uring_submit_timeout(ring, wait_nr, ts);
+		if (to_submit < 0)
+			return to_submit;
+	} else
+		to_submit = __io_uring_flush_sq(ring);
+
+	return __io_uring_get_cqe(ring, cqe_ptr, to_submit, wait_nr, sigmask);
+}
+
+/*
+ * See io_uring_wait_cqes() - this function is the same, it just always uses
+ * '1' as the wait_nr.
+ */
+int io_uring_wait_cqe_timeout(struct io_uring *ring,
+			      struct io_uring_cqe **cqe_ptr,
+			      struct __kernel_timespec *ts)
+{
+	return io_uring_wait_cqes(ring, cqe_ptr, 1, ts, NULL);
+}
+
+/*
+ * Submit sqes acquired from io_uring_get_sqe() to the kernel.
+ *
+ * Returns number of sqes submitted
+ */
+static int __io_uring_submit(struct io_uring *ring, unsigned submitted,
+			     unsigned wait_nr, bool getevents)
+{
+	bool cq_needs_enter = getevents || wait_nr || cq_ring_needs_enter(ring);
+	unsigned flags;
+	int ret;
+
+	flags = 0;
+	if (sq_ring_needs_enter(ring, submitted, &flags) || cq_needs_enter) {
+		if (cq_needs_enter)
+			flags |= IORING_ENTER_GETEVENTS;
+		if (ring->int_flags & INT_FLAG_REG_RING)
+			flags |= IORING_ENTER_REGISTERED_RING;
+
+		ret = __sys_io_uring_enter(ring->enter_ring_fd, submitted,
+					   wait_nr, flags, NULL);
+	} else
+		ret = submitted;
+
+	return ret;
+}
+
+static int __io_uring_submit_and_wait(struct io_uring *ring, unsigned wait_nr)
+{
+	return __io_uring_submit(ring, __io_uring_flush_sq(ring), wait_nr, false);
+}
+
+/*
+ * Submit sqes acquired from io_uring_get_sqe() to the kernel.
+ *
+ * Returns number of sqes submitted
+ */
+int io_uring_submit(struct io_uring *ring)
+{
+	return __io_uring_submit_and_wait(ring, 0);
+}
+
+/*
+ * Like io_uring_submit(), but allows waiting for events as well.
+ *
+ * Returns number of sqes submitted
+ */
+int io_uring_submit_and_wait(struct io_uring *ring, unsigned wait_nr)
+{
+	return __io_uring_submit_and_wait(ring, wait_nr);
+}
+
+int io_uring_submit_and_get_events(struct io_uring *ring)
+{
+	return __io_uring_submit(ring, __io_uring_flush_sq(ring), 0, true);
+}
+
+#ifdef LIBURING_INTERNAL
+struct io_uring_sqe *io_uring_get_sqe(struct io_uring *ring)
+{
+	return _io_uring_get_sqe(ring);
+}
+#endif
+
+int __io_uring_sqring_wait(struct io_uring *ring)
+{
+	int flags = IORING_ENTER_SQ_WAIT;
+
+	if (ring->int_flags & INT_FLAG_REG_RING)
+		flags |= IORING_ENTER_REGISTERED_RING;
+
+	return __sys_io_uring_enter(ring->enter_ring_fd, 0, 0, flags, NULL);
+}