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7980d7b199409fbb1547dd058655e40323bb3172
omarchy-pkgs/pkgbuilds/linux-omarchy/0601-usb4stream-busy-poll.patch
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diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
index 35e3c119d5ee..a4816db5cacd 100644
--- a/drivers/thunderbolt/nhi.c
+++ b/drivers/thunderbolt/nhi.c
@@ -235,6 +235,12 @@ static void ring_write_descriptors(struct tb_ring *ring)
{
struct ring_frame *frame, *n;
struct ring_desc *descriptor;
+ u32 flags;
+
+ flags = RING_DESC_POSTED;
+ if (!(ring->flags & RING_FLAG_NO_INTERRUPT))
+ flags |= RING_DESC_INTERRUPT;
+
list_for_each_entry_safe(frame, n, &ring->queue, list) {
if (ring_full(ring))
break;
@@ -242,7 +248,7 @@ static void ring_write_descriptors(struct tb_ring *ring)
descriptor = &ring->descriptors[ring->head];
descriptor->phys = frame->buffer_phy;
descriptor->time = 0;
- descriptor->flags = RING_DESC_POSTED | RING_DESC_INTERRUPT;
+ descriptor->flags = flags;
if (ring->is_tx) {
descriptor->length = frame->size;
descriptor->eof = frame->eof;
@@ -339,8 +345,9 @@ EXPORT_SYMBOL_GPL(__tb_ring_enqueue);
* @ring: Ring to poll
*
* This function can be called when @start_poll callback of the @ring
- * has been called. It will read one completed frame from the ring and
- * return it to the caller.
+ * has been called or the ring is created with %RING_FLAG_NO_INTERRUPT.
+ * It will read one completed frame from the ring and return it to the
+ * caller.
*
* Return: Pointer to &struct ring_frame, %NULL if there is no more
* completed frames.
@@ -538,6 +545,12 @@ static struct tb_ring *tb_ring_alloc(struct tb_nhi *nhi, u32 hop, int size,
dev_dbg(nhi->dev, "allocating %s ring %d of size %d\n",
transmit ? "TX" : "RX", hop, size);
+ if ((flags & RING_FLAG_NO_INTERRUPT) && start_poll) {
+ dev_WARN(nhi->dev,
+ "start_poll() and NO_INTERRUPT cannot be used at the same time\n");
+ return NULL;
+ }
+
ring = kzalloc_obj(*ring);
if (!ring)
return NULL;
@@ -568,7 +581,7 @@ static struct tb_ring *tb_ring_alloc(struct tb_nhi *nhi, u32 hop, int size,
if (!ring->descriptors)
goto err_free_ring;
- if (nhi->ops->request_ring_irq) {
+ if (!(flags & RING_FLAG_NO_INTERRUPT) && nhi->ops->request_ring_irq) {
if (nhi->ops->request_ring_irq(ring, flags & RING_FLAG_NO_SUSPEND))
goto err_free_descs;
}
@@ -701,7 +714,8 @@ void tb_ring_start(struct tb_ring *ring)
ring_iowrite32options(ring, flags, 0);
}
- ring_interrupt_active(ring, true);
+ if (!(ring->flags & RING_FLAG_NO_INTERRUPT))
+ ring_interrupt_active(ring, true);
ring->running = true;
err:
spin_unlock(&ring->lock);
@@ -761,7 +775,8 @@ void tb_ring_stop(struct tb_ring *ring)
RING_TYPE(ring), ring->hop);
goto err;
}
- ring_interrupt_active(ring, false);
+ if (!(ring->flags & RING_FLAG_NO_INTERRUPT))
+ ring_interrupt_active(ring, false);
ring_iowrite32options(ring, 0, 0);
ring_iowrite64desc(ring, 0, 0);
diff --git a/drivers/thunderbolt/stream.c b/drivers/thunderbolt/stream.c
index 43d29d69dcdb..a7d9fda66875 100644
--- a/drivers/thunderbolt/stream.c
+++ b/drivers/thunderbolt/stream.c
@@ -9,10 +9,12 @@
#define pr_fmt(fmt) "tbstream: " fmt
+#include <linux/delay.h>
#include <linux/configfs.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/idr.h>
+#include <linux/ktime.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mutex.h>
@@ -128,6 +130,7 @@ struct tbstream_ring {
* @out_hopid: Out HopID
* @ring_size: Size of the rings
* @throttling: Interrupt throttling rate in ns
+ * @busy_poll: Instead of interrupts, busy poll the rings
* @users: Number of times @cdev has been opened
* @closed: CLOSE packet was received
* @removed: Userspace removed the ConfigFS group underneath.
@@ -147,6 +150,7 @@ struct tbstream_dev {
int out_hopid;
unsigned int ring_size;
unsigned int throttling;
+ bool busy_poll;
int users;
bool closed;
bool removed;
@@ -536,10 +540,39 @@ tbstream_dev_send_data(struct tbstream_dev *sdev, struct iov_iter *from,
return tb_ring_tx(sdev->tx_ring.ring, &sf->frame);
}
+static void
+tbstream_dev_poll_ring(struct tbstream_dev *sdev, struct tbstream_ring *ring)
+{
+ struct ring_frame *frame;
+
+ if (!sdev->busy_poll)
+ return;
+
+ while ((frame = tb_ring_poll(ring->ring)))
+ frame->callback(ring->ring, frame, false);
+}
+
static int tbstream_dev_send_close(struct tbstream_dev *sdev)
{
struct tbstream_frame *sf;
+ if (sdev->busy_poll) {
+ /*
+ * When busy polling it's the write(2) path that
+ * advances the completions so it is possible that the
+ * ring is full at this point. Advance the ring here so
+ * that there is room for the CLOSE packet to be sent.
+ */
+ ktime_t timeout = ktime_add_ms(ktime_get(), 500);
+
+ do {
+ if (tbstream_ring_available(&sdev->tx_ring))
+ break;
+ tbstream_dev_poll_ring(sdev, &sdev->tx_ring);
+ fsleep(15);
+ } while (ktime_before(ktime_get(), timeout));
+ }
+
sf = tbstream_dev_alloc_tx(sdev, TBSTREAM_CLOSE, NULL, SZ_256);
if (IS_ERR(sf))
return PTR_ERR(sf);
@@ -549,12 +582,15 @@ static int tbstream_dev_send_close(struct tbstream_dev *sdev)
static int tbstream_dev_start(struct tbstream_dev *sdev)
{
struct tb_xdomain *xd = tbstream_dev_xdomain(sdev);
+ unsigned int flags = RING_FLAG_FRAME | RING_FLAG_E2E;
u16 sof_mask, eof_mask;
struct tb_ring *ring;
int ret, e2e_tx_hop;
- ring = tb_ring_alloc_tx(xd->tb->nhi, -1, sdev->ring_size,
- RING_FLAG_FRAME | RING_FLAG_E2E);
+ if (sdev->busy_poll)
+ flags |= RING_FLAG_NO_INTERRUPT;
+
+ ring = tb_ring_alloc_tx(xd->tb->nhi, -1, sdev->ring_size, flags);
if (!ring)
return -ENOMEM;
sdev->tx_ring.ring = ring;
@@ -567,9 +603,8 @@ static int tbstream_dev_start(struct tbstream_dev *sdev)
sof_mask = BIT(TBSTREAM_FRAME_START);
eof_mask = BIT(TBSTREAM_DATA) | BIT(TBSTREAM_CLOSE);
- ring = tb_ring_alloc_rx(xd->tb->nhi, -1, sdev->ring_size,
- RING_FLAG_FRAME | RING_FLAG_E2E, e2e_tx_hop,
- sof_mask, eof_mask, NULL, NULL);
+ ring = tb_ring_alloc_rx(xd->tb->nhi, -1, sdev->ring_size, flags,
+ e2e_tx_hop, sof_mask, eof_mask, NULL, NULL);
if (!ring) {
ret = -ENOMEM;
goto err_free_tx_buffers;
@@ -607,15 +642,43 @@ static int tbstream_dev_start(struct tbstream_dev *sdev)
return ret;
}
+static bool tbstream_dev_tx_drained(const struct tbstream_dev *sdev)
+{
+ const struct tbstream_ring *ring = &sdev->tx_ring;
+
+ /*
+ * Everything is completed when number of free TX slots is back
+ * to the maximum.
+ */
+ return ring->prod - ring->cons == tb_ring_size(ring->ring) - 1;
+}
+
static void tbstream_dev_stop(struct tbstream_dev *sdev)
{
struct tb_xdomain *xd;
- /* Wait for the ring to complete any outstanding frames */
- tb_ring_flush(sdev->tx_ring.ring, 500);
- tb_ring_stop(sdev->tx_ring.ring);
- tb_ring_flush(sdev->rx_ring.ring, 500);
- tb_ring_stop(sdev->rx_ring.ring);
+ if (sdev->busy_poll) {
+ /*
+ * When busy polling we must advance the ring ourselves
+ * to push all outstanding frames on the wire.
+ */
+ ktime_t timeout = ktime_add_ms(ktime_get(), 500);
+
+ do {
+ if (tbstream_dev_tx_drained(sdev))
+ break;
+ tbstream_dev_poll_ring(sdev, &sdev->tx_ring);
+ fsleep(15);
+ } while (ktime_before(ktime_get(), timeout));
+
+ tb_ring_stop(sdev->tx_ring.ring);
+ tb_ring_stop(sdev->rx_ring.ring);
+ } else {
+ tb_ring_flush(sdev->tx_ring.ring, 500);
+ tb_ring_stop(sdev->tx_ring.ring);
+ tb_ring_flush(sdev->rx_ring.ring, 500);
+ tb_ring_stop(sdev->rx_ring.ring);
+ }
xd = tbstream_dev_xdomain(sdev);
if (xd) {
@@ -633,10 +696,24 @@ static void tbstream_dev_stop(struct tbstream_dev *sdev)
sdev->tx_ring.ring = NULL;
}
+/* Use only with read_iter/write_iter() to handle nowait */
+static int tbstream_dev_lock(struct tbstream_dev *sdev, bool nowait)
+{
+ if (nowait) {
+ if (!mutex_trylock(&sdev->lock))
+ return -EAGAIN;
+ } else {
+ if (mutex_lock_interruptible(&sdev->lock))
+ return -ERESTARTSYS;
+ }
+ return 0;
+}
+
static ssize_t
tbstream_dev_fops_read_iter(struct kiocb *kiocb, struct iov_iter *to)
{
struct file *file = kiocb->ki_filp;
+ bool nowait = file->f_flags & O_NONBLOCK || kiocb->ki_flags & IOCB_NOWAIT;
struct tbstream_dev *sdev = to_tbstream_dev(file->private_data);
size_t nbytes;
int ret;
@@ -645,31 +722,50 @@ tbstream_dev_fops_read_iter(struct kiocb *kiocb, struct iov_iter *to)
if (ret)
return ret;
- if (mutex_lock_interruptible(&sdev->lock))
- return -ERESTARTSYS;
+ ret = tbstream_dev_lock(sdev, nowait);
+ if (ret)
+ return ret;
- while (!tbstream_ring_available(&sdev->rx_ring)) {
- mutex_unlock(&sdev->lock);
-
- if (file->f_flags & O_NONBLOCK)
- return -EAGAIN;
- ret = wait_event_interruptible(sdev->wait,
- tbstream_ring_available(&sdev->rx_ring) ||
- tbstream_dev_valid(sdev) != 0 ||
- tbstream_dev_closed(sdev) ||
- tbstream_dev_removed(sdev));
- if (ret)
- return ret;
+ for (;;) {
+ /* When busy polling, advance any completions manually */
+ tbstream_dev_poll_ring(sdev, &sdev->rx_ring);
ret = tbstream_dev_valid(sdev);
+ if (ret) {
+ mutex_unlock(&sdev->lock);
+ return ret;
+ }
+
+ if (tbstream_dev_closed(sdev) || tbstream_dev_removed(sdev)) {
+ mutex_unlock(&sdev->lock);
+ return 0;
+ }
+
+ if (tbstream_ring_available(&sdev->rx_ring))
+ break;
+
+ mutex_unlock(&sdev->lock);
+
+ if (nowait)
+ return -EAGAIN;
+
+ if (sdev->busy_poll) {
+ if (signal_pending(current))
+ return -ERESTARTSYS;
+ cond_resched();
+ } else {
+ ret = wait_event_interruptible(sdev->wait,
+ tbstream_ring_available(&sdev->rx_ring) ||
+ tbstream_dev_valid(sdev) != 0 ||
+ tbstream_dev_closed(sdev) ||
+ tbstream_dev_removed(sdev));
+ if (ret)
+ return ret;
+ }
+
+ ret = tbstream_dev_lock(sdev, nowait);
if (ret)
return ret;
-
- if (tbstream_dev_closed(sdev) || tbstream_dev_removed(sdev))
- return 0;
-
- if (mutex_lock_interruptible(&sdev->lock))
- return -ERESTARTSYS;
}
nbytes = 0;
@@ -729,6 +825,7 @@ static ssize_t
tbstream_dev_fops_write_iter(struct kiocb *kiocb, struct iov_iter *from)
{
struct file *file = kiocb->ki_filp;
+ bool nowait = file->f_flags & O_NONBLOCK || kiocb->ki_flags & IOCB_NOWAIT;
struct tbstream_dev *sdev = to_tbstream_dev(file->private_data);
size_t nbytes;
int ret;
@@ -737,31 +834,49 @@ tbstream_dev_fops_write_iter(struct kiocb *kiocb, struct iov_iter *from)
if (ret)
return ret;
- if (mutex_lock_interruptible(&sdev->lock))
- return -ERESTARTSYS;
+ ret = tbstream_dev_lock(sdev, nowait);
+ if (ret)
+ return ret;
- while (!tbstream_ring_available(&sdev->tx_ring)) {
- mutex_unlock(&sdev->lock);
-
- if (file->f_flags & O_NONBLOCK)
- return -EAGAIN;
- ret = wait_event_interruptible(sdev->wait,
- tbstream_ring_available(&sdev->tx_ring) ||
- tbstream_dev_valid(sdev) != 0 ||
- tbstream_dev_closed(sdev) ||
- tbstream_dev_removed(sdev));
- if (ret)
- return ret;
+ for (;;) {
+ tbstream_dev_poll_ring(sdev, &sdev->tx_ring);
ret = tbstream_dev_valid(sdev);
+ if (ret) {
+ mutex_unlock(&sdev->lock);
+ return ret;
+ }
+
+ if (tbstream_dev_closed(sdev) || tbstream_dev_removed(sdev)) {
+ mutex_unlock(&sdev->lock);
+ return -ENXIO;
+ }
+
+ if (tbstream_ring_available(&sdev->tx_ring))
+ break;
+
+ mutex_unlock(&sdev->lock);
+
+ if (nowait)
+ return -EAGAIN;
+
+ if (sdev->busy_poll) {
+ if (signal_pending(current))
+ return -ERESTARTSYS;
+ cond_resched();
+ } else {
+ ret = wait_event_interruptible(sdev->wait,
+ tbstream_ring_available(&sdev->tx_ring) ||
+ tbstream_dev_valid(sdev) != 0 ||
+ tbstream_dev_closed(sdev) ||
+ tbstream_dev_removed(sdev));
+ if (ret)
+ return ret;
+ }
+
+ ret = tbstream_dev_lock(sdev, nowait);
if (ret)
return ret;
-
- if (tbstream_dev_closed(sdev) || tbstream_dev_removed(sdev))
- return -ENXIO;
-
- if (mutex_lock_interruptible(&sdev->lock))
- return -ERESTARTSYS;
}
nbytes = 0;
@@ -795,6 +910,13 @@ tbstream_dev_fops_poll(struct file *file, struct poll_table_struct *wait)
struct tbstream_dev *sdev = to_tbstream_dev(file->private_data);
__poll_t mask = 0;
+ /*
+ * Without interrupts there is nothing that can wake us up so
+ * return failure instead.
+ */
+ if (sdev->busy_poll)
+ return EPOLLERR;
+
poll_wait(file, &sdev->wait, wait);
guard(mutex)(&sdev->lock);
if (tbstream_dev_valid(sdev) != 0) {
@@ -904,6 +1026,35 @@ tbstream_dev_from_group(struct config_group *group)
return container_of(group, struct tbstream_dev, group);
}
+static ssize_t tbstream_dev_busy_poll_show(struct config_item *item, char *buf)
+{
+ struct config_group *group = to_config_group(item);
+ struct tbstream_dev *sdev = tbstream_dev_from_group(group);
+
+ return sysfs_emit(buf, "%u\n", sdev->busy_poll);
+}
+
+static ssize_t
+tbstream_dev_busy_poll_store(struct config_item *item, const char *buf,
+ size_t count)
+{
+ struct config_group *group = to_config_group(item);
+ struct tbstream_dev *sdev = tbstream_dev_from_group(group);
+ bool busy_poll;
+ int ret;
+
+ ret = kstrtobool(buf, &busy_poll);
+ if (ret)
+ return ret;
+
+ guard(mutex)(&sdev->lock);
+ if (sdev->users)
+ return -EBUSY;
+ sdev->busy_poll = busy_poll;
+ return count;
+}
+CONFIGFS_ATTR(tbstream_dev_, busy_poll);
+
static ssize_t tbstream_dev_index_show(struct config_item *item, char *buf)
{
struct config_group *group = to_config_group(item);
@@ -1210,6 +1361,7 @@ tbstream_dev_throttling_store(struct config_item *item, const char *buf,
CONFIGFS_ATTR(tbstream_dev_, throttling);
static struct configfs_attribute *tbstream_dev_attrs[] = {
+ &tbstream_dev_attr_busy_poll,
&tbstream_dev_attr_index,
&tbstream_dev_attr_in_hopid,
&tbstream_dev_attr_out_hopid,
diff --git a/include/linux/thunderbolt.h b/include/linux/thunderbolt.h
index 557288c0274b..8367d106d81b 100644
--- a/include/linux/thunderbolt.h
+++ b/include/linux/thunderbolt.h
@@ -592,6 +592,8 @@ struct tb_ring {
#define RING_FLAG_FRAME BIT(1)
/* Enable end-to-end flow control */
#define RING_FLAG_E2E BIT(2)
+/* Do not enable interrupt for the ring */
+#define RING_FLAG_NO_INTERRUPT BIT(3)
struct ring_frame;
typedef void (*ring_cb)(struct tb_ring *, struct ring_frame *, bool canceled);
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