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Subject[RFC PATCH v2 8/9] hyper_dmabuf: event-polling mechanism for detecting a new hyper_DMABUF
Date
New method based on polling for a importing VM to know about a new
hyper_DMABUF exported to it.

For this, the userspace now can poll the device node to check if
there a new event, which is created if there's a new hyper_DMABUF
available in importing VM (just exported).

A poll function call was added to the device driver interface for this
new functionality. Event-generation functionalitywas also implemented in
all other relavant parts of driver.

This "event-polling" mechanism is optional feature and can be enabled
by setting a Kernel config option, "HYPER_DMABUF_EVENT_GEN".

Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
Signed-off-by: Mateusz Polrola <mateuszx.potrola@intel.com>
---
drivers/dma-buf/hyper_dmabuf/Kconfig | 20 +++
drivers/dma-buf/hyper_dmabuf/Makefile | 1 +
drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_drv.c | 146 ++++++++++++++++++++++
drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_drv.h | 11 ++
drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_event.c | 122 ++++++++++++++++++
drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_event.h | 38 ++++++
drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_list.c | 1 +
drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_msg.c | 11 ++
include/uapi/linux/hyper_dmabuf.h | 11 ++
9 files changed, 361 insertions(+)
create mode 100644 drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_event.c
create mode 100644 drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_event.h

diff --git a/drivers/dma-buf/hyper_dmabuf/Kconfig b/drivers/dma-buf/hyper_dmabuf/Kconfig
index 68f3d6ce2c1f..92510731af25 100644
--- a/drivers/dma-buf/hyper_dmabuf/Kconfig
+++ b/drivers/dma-buf/hyper_dmabuf/Kconfig
@@ -20,6 +20,16 @@ config HYPER_DMABUF_SYSFS

The location of sysfs is under "...."

+config HYPER_DMABUF_EVENT_GEN
+ bool "Enable event-generation and polling operation"
+ default n
+ depends on HYPER_DMABUF
+ help
+ With this config enabled, hyper_dmabuf driver on the importer side
+ generates events and queue those up in the event list whenever a new
+ shared DMA-BUF is available. Events in the list can be retrieved by
+ read operation.
+
config HYPER_DMABUF_XEN
bool "Configure hyper_dmabuf for XEN hypervisor"
default y
@@ -27,4 +37,14 @@ config HYPER_DMABUF_XEN
help
Enabling Hyper_DMABUF Backend for XEN hypervisor

+config HYPER_DMABUF_XEN_AUTO_RX_CH_ADD
+ bool "Enable automatic rx-ch add with 10 secs interval"
+ default y
+ depends on HYPER_DMABUF && HYPER_DMABUF_XEN
+ help
+ If enabled, driver reads a node in xenstore every 10 seconds
+ to check whether there is any tx comm ch configured by another
+ domain then initialize matched rx comm ch automatically for any
+ existing tx comm chs.
+
endmenu
diff --git a/drivers/dma-buf/hyper_dmabuf/Makefile b/drivers/dma-buf/hyper_dmabuf/Makefile
index 578a669a0d3e..f573dd5c4054 100644
--- a/drivers/dma-buf/hyper_dmabuf/Makefile
+++ b/drivers/dma-buf/hyper_dmabuf/Makefile
@@ -11,6 +11,7 @@ ifneq ($(KERNELRELEASE),)
hyper_dmabuf_id.o \
hyper_dmabuf_remote_sync.o \
hyper_dmabuf_query.o \
+ hyper_dmabuf_event.o \

ifeq ($(CONFIG_HYPER_DMABUF_XEN), y)
$(TARGET_MODULE)-objs += backends/xen/hyper_dmabuf_xen_comm.o \
diff --git a/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_drv.c b/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_drv.c
index 3320f9dcc769..087f091ccae9 100644
--- a/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_drv.c
+++ b/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_drv.c
@@ -41,6 +41,7 @@
#include "hyper_dmabuf_ioctl.h"
#include "hyper_dmabuf_list.h"
#include "hyper_dmabuf_id.h"
+#include "hyper_dmabuf_event.h"

#ifdef CONFIG_HYPER_DMABUF_XEN
#include "backends/xen/hyper_dmabuf_xen_drv.h"
@@ -91,10 +92,138 @@ static int hyper_dmabuf_release(struct inode *inode, struct file *filp)
return 0;
}

+#ifdef CONFIG_HYPER_DMABUF_EVENT_GEN
+
+static unsigned int hyper_dmabuf_event_poll(struct file *filp,
+ struct poll_table_struct *wait)
+{
+ poll_wait(filp, &hy_drv_priv->event_wait, wait);
+
+ if (!list_empty(&hy_drv_priv->event_list))
+ return POLLIN | POLLRDNORM;
+
+ return 0;
+}
+
+static ssize_t hyper_dmabuf_event_read(struct file *filp, char __user *buffer,
+ size_t count, loff_t *offset)
+{
+ int ret;
+
+ /* only root can read events */
+ if (!capable(CAP_DAC_OVERRIDE)) {
+ dev_err(hy_drv_priv->dev,
+ "Only root can read events\n");
+ return -EPERM;
+ }
+
+ /* make sure user buffer can be written */
+ if (!access_ok(VERIFY_WRITE, buffer, count)) {
+ dev_err(hy_drv_priv->dev,
+ "User buffer can't be written.\n");
+ return -EINVAL;
+ }
+
+ ret = mutex_lock_interruptible(&hy_drv_priv->event_read_lock);
+ if (ret)
+ return ret;
+
+ while (1) {
+ struct hyper_dmabuf_event *e = NULL;
+
+ spin_lock_irq(&hy_drv_priv->event_lock);
+ if (!list_empty(&hy_drv_priv->event_list)) {
+ e = list_first_entry(&hy_drv_priv->event_list,
+ struct hyper_dmabuf_event, link);
+ list_del(&e->link);
+ }
+ spin_unlock_irq(&hy_drv_priv->event_lock);
+
+ if (!e) {
+ if (ret)
+ break;
+
+ if (filp->f_flags & O_NONBLOCK) {
+ ret = -EAGAIN;
+ break;
+ }
+
+ mutex_unlock(&hy_drv_priv->event_read_lock);
+ ret = wait_event_interruptible(hy_drv_priv->event_wait,
+ !list_empty(&hy_drv_priv->event_list));
+
+ if (ret == 0)
+ ret = mutex_lock_interruptible(
+ &hy_drv_priv->event_read_lock);
+
+ if (ret)
+ return ret;
+ } else {
+ unsigned int length = (sizeof(e->event_data.hdr) +
+ e->event_data.hdr.size);
+
+ if (length > count - ret) {
+put_back_event:
+ spin_lock_irq(&hy_drv_priv->event_lock);
+ list_add(&e->link, &hy_drv_priv->event_list);
+ spin_unlock_irq(&hy_drv_priv->event_lock);
+ break;
+ }
+
+ if (copy_to_user(buffer + ret, &e->event_data.hdr,
+ sizeof(e->event_data.hdr))) {
+ if (ret == 0)
+ ret = -EFAULT;
+
+ goto put_back_event;
+ }
+
+ ret += sizeof(e->event_data.hdr);
+
+ if (copy_to_user(buffer + ret, e->event_data.data,
+ e->event_data.hdr.size)) {
+ /* error while copying void *data */
+
+ struct hyper_dmabuf_event_hdr dummy_hdr = {0};
+
+ ret -= sizeof(e->event_data.hdr);
+
+ /* nullifying hdr of the event in user buffer */
+ if (copy_to_user(buffer + ret, &dummy_hdr,
+ sizeof(dummy_hdr))) {
+ dev_err(hy_drv_priv->dev,
+ "failed to nullify invalid hdr already in userspace\n");
+ }
+
+ ret = -EFAULT;
+
+ goto put_back_event;
+ }
+
+ ret += e->event_data.hdr.size;
+ hy_drv_priv->pending--;
+ kfree(e);
+ }
+ }
+
+ mutex_unlock(&hy_drv_priv->event_read_lock);
+
+ return ret;
+}
+
+#endif
+
static const struct file_operations hyper_dmabuf_driver_fops = {
.owner = THIS_MODULE,
.open = hyper_dmabuf_open,
.release = hyper_dmabuf_release,
+
+/* poll and read interfaces are needed only for event-polling */
+#ifdef CONFIG_HYPER_DMABUF_EVENT_GEN
+ .read = hyper_dmabuf_event_read,
+ .poll = hyper_dmabuf_event_poll,
+#endif
+
.unlocked_ioctl = hyper_dmabuf_ioctl,
};

@@ -194,6 +323,18 @@ static int __init hyper_dmabuf_drv_init(void)
}
#endif

+#ifdef CONFIG_HYPER_DMABUF_EVENT_GEN
+ mutex_init(&hy_drv_priv->event_read_lock);
+ spin_lock_init(&hy_drv_priv->event_lock);
+
+ /* Initialize event queue */
+ INIT_LIST_HEAD(&hy_drv_priv->event_list);
+ init_waitqueue_head(&hy_drv_priv->event_wait);
+
+ /* resetting number of pending events */
+ hy_drv_priv->pending = 0;
+#endif
+
if (hy_drv_priv->bknd_ops->init) {
ret = hy_drv_priv->bknd_ops->init();

@@ -250,6 +391,11 @@ static void hyper_dmabuf_drv_exit(void)
if (hy_drv_priv->id_queue)
hyper_dmabuf_free_hid_list();

+#ifdef CONFIG_HYPER_DMABUF_EVENT_GEN
+ /* clean up event queue */
+ hyper_dmabuf_events_release();
+#endif
+
mutex_unlock(&hy_drv_priv->lock);

dev_info(hy_drv_priv->dev,
diff --git a/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_drv.h b/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_drv.h
index 46119d762430..282a507b33bc 100644
--- a/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_drv.h
+++ b/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_drv.h
@@ -32,6 +32,11 @@

struct hyper_dmabuf_req;

+struct hyper_dmabuf_event {
+ struct hyper_dmabuf_event_data event_data;
+ struct list_head link;
+};
+
struct hyper_dmabuf_private {
struct device *dev;

@@ -54,6 +59,12 @@ struct hyper_dmabuf_private {
/* flag that shows whether backend is initialized */
bool initialized;

+ wait_queue_head_t event_wait;
+ struct list_head event_list;
+
+ spinlock_t event_lock;
+ struct mutex event_read_lock;
+
/* # of pending events */
int pending;
};
diff --git a/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_event.c b/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_event.c
new file mode 100644
index 000000000000..942a1bb78755
--- /dev/null
+++ b/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_event.c
@@ -0,0 +1,122 @@
+/*
+ * Copyright © 2018 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ * Dongwon Kim <dongwon.kim@intel.com>
+ * Mateusz Polrola <mateuszx.potrola@intel.com>
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include "hyper_dmabuf_drv.h"
+#include "hyper_dmabuf_struct.h"
+#include "hyper_dmabuf_list.h"
+#include "hyper_dmabuf_event.h"
+
+static void send_event(struct hyper_dmabuf_event *e)
+{
+ struct hyper_dmabuf_event *oldest;
+ unsigned long irqflags;
+
+ spin_lock_irqsave(&hy_drv_priv->event_lock, irqflags);
+
+ /* check current number of event then if it hits the max num allowed
+ * then remove the oldest event in the list
+ */
+ if (hy_drv_priv->pending > MAX_DEPTH_EVENT_QUEUE - 1) {
+ oldest = list_first_entry(&hy_drv_priv->event_list,
+ struct hyper_dmabuf_event, link);
+ list_del(&oldest->link);
+ hy_drv_priv->pending--;
+ kfree(oldest);
+ }
+
+ list_add_tail(&e->link,
+ &hy_drv_priv->event_list);
+
+ hy_drv_priv->pending++;
+
+ wake_up_interruptible(&hy_drv_priv->event_wait);
+
+ spin_unlock_irqrestore(&hy_drv_priv->event_lock, irqflags);
+}
+
+void hyper_dmabuf_events_release(void)
+{
+ struct hyper_dmabuf_event *e, *et;
+ unsigned long irqflags;
+
+ spin_lock_irqsave(&hy_drv_priv->event_lock, irqflags);
+
+ list_for_each_entry_safe(e, et, &hy_drv_priv->event_list,
+ link) {
+ list_del(&e->link);
+ kfree(e);
+ hy_drv_priv->pending--;
+ }
+
+ if (hy_drv_priv->pending) {
+ dev_err(hy_drv_priv->dev,
+ "possible leak on event_list\n");
+ }
+
+ spin_unlock_irqrestore(&hy_drv_priv->event_lock, irqflags);
+}
+
+int hyper_dmabuf_import_event(hyper_dmabuf_id_t hid)
+{
+ struct hyper_dmabuf_event *e;
+ struct imported_sgt_info *imported;
+
+ imported = hyper_dmabuf_find_imported(hid);
+
+ if (!imported) {
+ dev_err(hy_drv_priv->dev,
+ "can't find imported_sgt_info in the list\n");
+ return -EINVAL;
+ }
+
+ e = kzalloc(sizeof(*e), GFP_KERNEL);
+
+ if (!e)
+ return -ENOMEM;
+
+ e->event_data.hdr.event_type = HYPER_DMABUF_NEW_IMPORT;
+ e->event_data.hdr.hid = hid;
+ e->event_data.data = (void *)imported->priv;
+ e->event_data.hdr.size = imported->sz_priv;
+
+ send_event(e);
+
+ dev_dbg(hy_drv_priv->dev,
+ "event number = %d :", hy_drv_priv->pending);
+
+ dev_dbg(hy_drv_priv->dev,
+ "generating events for {%d, %d, %d, %d}\n",
+ imported->hid.id, imported->hid.rng_key[0],
+ imported->hid.rng_key[1], imported->hid.rng_key[2]);
+
+ return 0;
+}
diff --git a/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_event.h b/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_event.h
new file mode 100644
index 000000000000..8f61198e623c
--- /dev/null
+++ b/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_event.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright © 2018 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#ifndef __HYPER_DMABUF_EVENT_H__
+#define __HYPER_DMABUF_EVENT_H__
+
+#define MAX_DEPTH_EVENT_QUEUE 32
+
+enum hyper_dmabuf_event_type {
+ HYPER_DMABUF_NEW_IMPORT = 0x10000,
+};
+
+void hyper_dmabuf_events_release(void);
+
+int hyper_dmabuf_import_event(hyper_dmabuf_id_t hid);
+
+#endif /* __HYPER_DMABUF_EVENT_H__ */
diff --git a/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_list.c b/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_list.c
index f2f65a8ec47f..30c3af65fcde 100644
--- a/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_list.c
+++ b/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_list.c
@@ -36,6 +36,7 @@
#include "hyper_dmabuf_drv.h"
#include "hyper_dmabuf_list.h"
#include "hyper_dmabuf_id.h"
+#include "hyper_dmabuf_event.h"

DECLARE_HASHTABLE(hyper_dmabuf_hash_imported, MAX_ENTRY_IMPORTED);
DECLARE_HASHTABLE(hyper_dmabuf_hash_exported, MAX_ENTRY_EXPORTED);
diff --git a/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_msg.c b/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_msg.c
index 1592d5cfaa52..8f2cf7ea827d 100644
--- a/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_msg.c
+++ b/drivers/dma-buf/hyper_dmabuf/hyper_dmabuf_msg.c
@@ -35,6 +35,7 @@
#include "hyper_dmabuf_drv.h"
#include "hyper_dmabuf_msg.h"
#include "hyper_dmabuf_remote_sync.h"
+#include "hyper_dmabuf_event.h"
#include "hyper_dmabuf_list.h"

struct cmd_process {
@@ -179,6 +180,11 @@ static void cmd_process_work(struct work_struct *work)
/* updating priv data */
memcpy(imported->priv, &req->op[9], req->op[8]);

+#ifdef CONFIG_HYPER_DMABUF_EVENT_GEN
+ /* generating import event */
+ hyper_dmabuf_import_event(imported->hid);
+#endif
+
break;
}

@@ -219,6 +225,11 @@ static void cmd_process_work(struct work_struct *work)
imported->valid = true;
hyper_dmabuf_register_imported(imported);

+#ifdef CONFIG_HYPER_DMABUF_EVENT_GEN
+ /* generating import event */
+ hyper_dmabuf_import_event(imported->hid);
+#endif
+
break;

case HYPER_DMABUF_OPS_TO_REMOTE:
diff --git a/include/uapi/linux/hyper_dmabuf.h b/include/uapi/linux/hyper_dmabuf.h
index 4f8e8ac0375b..dd73db9bf37d 100644
--- a/include/uapi/linux/hyper_dmabuf.h
+++ b/include/uapi/linux/hyper_dmabuf.h
@@ -32,6 +32,17 @@ typedef struct {
int rng_key[3]; /* 12bytes long random number */
} hyper_dmabuf_id_t;

+struct hyper_dmabuf_event_hdr {
+ int event_type; /* one type only for now - new import */
+ hyper_dmabuf_id_t hid; /* hyper_dmabuf_id of specific hyper_dmabuf */
+ int size; /* size of data */
+};
+
+struct hyper_dmabuf_event_data {
+ struct hyper_dmabuf_event_hdr hdr;
+ void *data; /* private data */
+};
+
#define IOCTL_HYPER_DMABUF_TX_CH_SETUP \
_IOC(_IOC_NONE, 'G', 0, sizeof(struct ioctl_hyper_dmabuf_tx_ch_setup))
struct ioctl_hyper_dmabuf_tx_ch_setup {
--
2.16.1
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