tools/usb/ffs-aio-example/multibuff/device_app/aio_multibuff.c - linux - Git at Google

 /*
  * This is free and unencumbered software released into the public domain.
  *
  * Anyone is free to copy, modify, publish, use, compile, sell, or
  * distribute this software, either in source code form or as a compiled
  * binary, for any purpose, commercial or non-commercial, and by any
  * means.
  *
  * In jurisdictions that recognize copyright laws, the author or authors
  * of this software dedicate any and all copyright interest in the
  * software to the public domain. We make this dedication for the benefit
  * of the public at large and to the detriment of our heirs and
  * successors. We intend this dedication to be an overt act of
  * relinquishment in perpetuity of all present and future rights to this
  * software under copyright law.
  *
  * 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 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.
  *
  * For more information, please refer to <http://unlicense.org/>
  */

 #define _BSD_SOURCE /* for endian.h */

 #include <endian.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/ioctl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/poll.h>
 #include <unistd.h>
 #include <stdbool.h>
 #include <sys/eventfd.h>

 #include "libaio.h"
 #define IOCB_FLAG_RESFD         (1 << 0)

 #include <linux/usb/functionfs.h>

 #define BUF_LEN		8192
 #define BUFS_MAX	128
 #define AIO_MAX		(BUFS_MAX*2)

 /******************** Descriptors and Strings *******************************/

 static const struct {
 	struct usb_functionfs_descs_head_v2 header;
 	__le32 fs_count;
 	__le32 hs_count;
 	struct {
 		struct usb_interface_descriptor intf;
 		struct usb_endpoint_descriptor_no_audio bulk_sink;
 		struct usb_endpoint_descriptor_no_audio bulk_source;
 	} __attribute__ ((__packed__)) fs_descs, hs_descs;
 } __attribute__ ((__packed__)) descriptors = {
 	.header = {
 		.magic = htole32(FUNCTIONFS_DESCRIPTORS_MAGIC_V2),
 		.flags = htole32(FUNCTIONFS_HAS_FS_DESC |
 				     FUNCTIONFS_HAS_HS_DESC),
 		.length = htole32(sizeof(descriptors)),
 	},
 	.fs_count = htole32(3),
 	.fs_descs = {
 		.intf = {
 			.bLength = sizeof(descriptors.fs_descs.intf),
 			.bDescriptorType = USB_DT_INTERFACE,
 			.bNumEndpoints = 2,
 			.bInterfaceClass = USB_CLASS_VENDOR_SPEC,
 			.iInterface = 1,
 		},
 		.bulk_sink = {
 			.bLength = sizeof(descriptors.fs_descs.bulk_sink),
 			.bDescriptorType = USB_DT_ENDPOINT,
 			.bEndpointAddress = 1 | USB_DIR_IN,
 			.bmAttributes = USB_ENDPOINT_XFER_BULK,
 		},
 		.bulk_source = {
 			.bLength = sizeof(descriptors.fs_descs.bulk_source),
 			.bDescriptorType = USB_DT_ENDPOINT,
 			.bEndpointAddress = 2 | USB_DIR_OUT,
 			.bmAttributes = USB_ENDPOINT_XFER_BULK,
 		},
 	},
 	.hs_count = htole32(3),
 	.hs_descs = {
 		.intf = {
 			.bLength = sizeof(descriptors.hs_descs.intf),
 			.bDescriptorType = USB_DT_INTERFACE,
 			.bNumEndpoints = 2,
 			.bInterfaceClass = USB_CLASS_VENDOR_SPEC,
 			.iInterface = 1,
 		},
 		.bulk_sink = {
 			.bLength = sizeof(descriptors.hs_descs.bulk_sink),
 			.bDescriptorType = USB_DT_ENDPOINT,
 			.bEndpointAddress = 1 | USB_DIR_IN,
 			.bmAttributes = USB_ENDPOINT_XFER_BULK,
 			.wMaxPacketSize = htole16(512),
 		},
 		.bulk_source = {
 			.bLength = sizeof(descriptors.hs_descs.bulk_source),
 			.bDescriptorType = USB_DT_ENDPOINT,
 			.bEndpointAddress = 2 | USB_DIR_OUT,
 			.bmAttributes = USB_ENDPOINT_XFER_BULK,
 			.wMaxPacketSize = htole16(512),
 		},
 	},
 };

 #define STR_INTERFACE "AIO Test"

 static const struct {
 	struct usb_functionfs_strings_head header;
 	struct {
 		__le16 code;
 		const char str1[sizeof(STR_INTERFACE)];
 	} __attribute__ ((__packed__)) lang0;
 } __attribute__ ((__packed__)) strings = {
 	.header = {
 		.magic = htole32(FUNCTIONFS_STRINGS_MAGIC),
 		.length = htole32(sizeof(strings)),
 		.str_count = htole32(1),
 		.lang_count = htole32(1),
 	},
 	.lang0 = {
 		htole16(0x0409), /* en-us */
 		STR_INTERFACE,
 	},
 };

 /********************** Buffer structure *******************************/

 struct io_buffer {
 	struct iocb **iocb;
 	unsigned char **buf;
 	unsigned cnt;
 	unsigned len;
 	unsigned requested;
 };

 /******************** Endpoints handling *******************************/

 static void display_event(struct usb_functionfs_event *event)
 {
 	static const char *const names[] = {
 		[FUNCTIONFS_BIND] = "BIND",
 		[FUNCTIONFS_UNBIND] = "UNBIND",
 		[FUNCTIONFS_ENABLE] = "ENABLE",
 		[FUNCTIONFS_DISABLE] = "DISABLE",
 		[FUNCTIONFS_SETUP] = "SETUP",
 		[FUNCTIONFS_SUSPEND] = "SUSPEND",
 		[FUNCTIONFS_RESUME] = "RESUME",
 	};
 	switch (event->type) {
 	case FUNCTIONFS_BIND:
 	case FUNCTIONFS_UNBIND:
 	case FUNCTIONFS_ENABLE:
 	case FUNCTIONFS_DISABLE:
 	case FUNCTIONFS_SETUP:
 	case FUNCTIONFS_SUSPEND:
 	case FUNCTIONFS_RESUME:
 		printf("Event %s\n", names[event->type]);
 	}
 }

 static void handle_ep0(int ep0, bool *ready)
 {
 	int ret;
 	struct usb_functionfs_event event;

 	ret = read(ep0, &event, sizeof(event));
 	if (!ret) {
 		perror("unable to read event from ep0");
 		return;
 	}
 	display_event(&event);
 	switch (event.type) {
 	case FUNCTIONFS_SETUP:
 		if (event.u.setup.bRequestType & USB_DIR_IN)
 			write(ep0, NULL, 0);
 		else
 			read(ep0, NULL, 0);
 		break;

 	case FUNCTIONFS_ENABLE:
 		*ready = true;
 		break;

 	case FUNCTIONFS_DISABLE:
 		*ready = false;
 		break;

 	default:
 		break;
 	}
 }

 void init_bufs(struct io_buffer *iobuf, unsigned n, unsigned len)
 {
 	unsigned i;
 	iobuf->buf = malloc(n*sizeof(*iobuf->buf));
 	iobuf->iocb = malloc(n*sizeof(*iobuf->iocb));
 	iobuf->cnt = n;
 	iobuf->len = len;
 	iobuf->requested = 0;
 	for (i = 0; i < n; ++i) {
 		iobuf->buf[i] = malloc(len*sizeof(**iobuf->buf));
 		iobuf->iocb[i] = malloc(sizeof(**iobuf->iocb));
 	}
 	iobuf->cnt = n;
 }

 void delete_bufs(struct io_buffer *iobuf)
 {
 	unsigned i;
 	for (i = 0; i < iobuf->cnt; ++i) {
 		free(iobuf->buf[i]);
 		free(iobuf->iocb[i]);
 	}
 	free(iobuf->buf);
 	free(iobuf->iocb);
 }

 int main(int argc, char *argv[])
 {
 	int ret;
 	unsigned i, j;
 	char *ep_path;

 	int ep0, ep1;

 	io_context_t ctx;

 	int evfd;
 	fd_set rfds;

 	struct io_buffer iobuf[2];
 	int actual = 0;
 	bool ready;

 	if (argc != 2) {
 		printf("ffs directory not specified!\n");
 		return 1;
 	}

 	ep_path = malloc(strlen(argv[1]) + 4 /* "/ep#" */ + 1 /* '\0' */);
 	if (!ep_path) {
 		perror("malloc");
 		return 1;
 	}

 	/* open endpoint files */
 	sprintf(ep_path, "%s/ep0", argv[1]);
 	ep0 = open(ep_path, O_RDWR);
 	if (ep0 < 0) {
 		perror("unable to open ep0");
 		return 1;
 	}
 	if (write(ep0, &descriptors, sizeof(descriptors)) < 0) {
 		perror("unable do write descriptors");
 		return 1;
 	}
 	if (write(ep0, &strings, sizeof(strings)) < 0) {
 		perror("unable to write strings");
 		return 1;
 	}
 	sprintf(ep_path, "%s/ep1", argv[1]);
 	ep1 = open(ep_path, O_RDWR);
 	if (ep1 < 0) {
 		perror("unable to open ep1");
 		return 1;
 	}

 	free(ep_path);

 	memset(&ctx, 0, sizeof(ctx));
 	/* setup aio context to handle up to AIO_MAX requests */
 	if (io_setup(AIO_MAX, &ctx) < 0) {
 		perror("unable to setup aio");
 		return 1;
 	}

 	evfd = eventfd(0, 0);
 	if (evfd < 0) {
 		perror("unable to open eventfd");
 		return 1;
 	}

 	for (i = 0; i < sizeof(iobuf)/sizeof(*iobuf); ++i)
 		init_bufs(&iobuf[i], BUFS_MAX, BUF_LEN);

 	while (1) {
 		FD_ZERO(&rfds);
 		FD_SET(ep0, &rfds);
 		FD_SET(evfd, &rfds);

 		ret = select(((ep0 > evfd) ? ep0 : evfd)+1,
 			     &rfds, NULL, NULL, NULL);
 		if (ret < 0) {
 			if (errno == EINTR)
 				continue;
 			perror("select");
 			break;
 		}

 		if (FD_ISSET(ep0, &rfds))
 			handle_ep0(ep0, &ready);

 		/* we are waiting for function ENABLE */
 		if (!ready)
 			continue;

 		/*
 		 * when we're preparing new data to submit,
 		 * second buffer being transmitted
 		 */
 		for (i = 0; i < sizeof(iobuf)/sizeof(*iobuf); ++i) {
 			if (iobuf[i].requested)
 				continue;
 			/* prepare requests */
 			for (j = 0; j < iobuf[i].cnt; ++j) {
 				io_prep_pwrite(iobuf[i].iocb[j], ep1,
 					       iobuf[i].buf[j],
 					       iobuf[i].len, 0);
 				/* enable eventfd notification */
 				iobuf[i].iocb[j]->u.c.flags |= IOCB_FLAG_RESFD;
 				iobuf[i].iocb[j]->u.c.resfd = evfd;
 			}
 			/* submit table of requests */
 			ret = io_submit(ctx, iobuf[i].cnt, iobuf[i].iocb);
 			if (ret >= 0) {
 				iobuf[i].requested = ret;
 				printf("submit: %d requests buf: %d\n", ret, i);
 			} else
 				perror("unable to submit requests");
 		}

 		/* if event is ready to read */
 		if (!FD_ISSET(evfd, &rfds))
 			continue;

 		uint64_t ev_cnt;
 		ret = read(evfd, &ev_cnt, sizeof(ev_cnt));
 		if (ret < 0) {
 			perror("unable to read eventfd");
 			break;
 		}

 		struct io_event e[BUFS_MAX];
 		/* we read aio events */
 		ret = io_getevents(ctx, 1, BUFS_MAX, e, NULL);
 		if (ret > 0) /* if we got events */
 			iobuf[actual].requested -= ret;

 		/* if all req's from iocb completed */
 		if (!iobuf[actual].requested)
 			actual = (actual + 1)%(sizeof(iobuf)/sizeof(*iobuf));
 	}

 	/* free resources */

 	for (i = 0; i < sizeof(iobuf)/sizeof(*iobuf); ++i)
 		delete_bufs(&iobuf[i]);
 	io_destroy(ctx);

 	close(ep1);
 	close(ep0);

 	return 0;
 }
	/*
	* This is free and unencumbered software released into the public domain.
	*
	* Anyone is free to copy, modify, publish, use, compile, sell, or
	* distribute this software, either in source code form or as a compiled
	* binary, for any purpose, commercial or non-commercial, and by any
	* means.
	*
	* In jurisdictions that recognize copyright laws, the author or authors
	* of this software dedicate any and all copyright interest in the
	* software to the public domain. We make this dedication for the benefit
	* of the public at large and to the detriment of our heirs and
	* successors. We intend this dedication to be an overt act of
	* relinquishment in perpetuity of all present and future rights to this
	* software under copyright law.
	*
	* 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 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.
	*
	* For more information, please refer to <http://unlicense.org/>
	*/

	#define _BSD_SOURCE /* for endian.h */

	#include <endian.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <stdarg.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/ioctl.h>
	#include <sys/stat.h>
	#include <sys/types.h>
	#include <sys/poll.h>
	#include <unistd.h>
	#include <stdbool.h>
	#include <sys/eventfd.h>

	#include "libaio.h"
	#define IOCB_FLAG_RESFD (1 << 0)

	#include <linux/usb/functionfs.h>

	#define BUF_LEN 8192
	#define BUFS_MAX 128
	#define AIO_MAX (BUFS_MAX*2)

	/****************** Descriptors and Strings *****************************/

	static const struct {
	struct usb_functionfs_descs_head_v2 header;
	__le32 fs_count;
	__le32 hs_count;
	struct {
	struct usb_interface_descriptor intf;
	struct usb_endpoint_descriptor_no_audio bulk_sink;
	struct usb_endpoint_descriptor_no_audio bulk_source;
	} __attribute__ ((__packed__)) fs_descs, hs_descs;
	} __attribute__ ((__packed__)) descriptors = {
	.header = {
	.magic = htole32(FUNCTIONFS_DESCRIPTORS_MAGIC_V2),
	.flags = htole32(FUNCTIONFS_HAS_FS_DESC \|
	FUNCTIONFS_HAS_HS_DESC),
	.length = htole32(sizeof(descriptors)),
	},
	.fs_count = htole32(3),
	.fs_descs = {
	.intf = {
	.bLength = sizeof(descriptors.fs_descs.intf),
	.bDescriptorType = USB_DT_INTERFACE,
	.bNumEndpoints = 2,
	.bInterfaceClass = USB_CLASS_VENDOR_SPEC,
	.iInterface = 1,
	},
	.bulk_sink = {
	.bLength = sizeof(descriptors.fs_descs.bulk_sink),
	.bDescriptorType = USB_DT_ENDPOINT,
	.bEndpointAddress = 1 \| USB_DIR_IN,
	.bmAttributes = USB_ENDPOINT_XFER_BULK,
	},
	.bulk_source = {
	.bLength = sizeof(descriptors.fs_descs.bulk_source),
	.bDescriptorType = USB_DT_ENDPOINT,
	.bEndpointAddress = 2 \| USB_DIR_OUT,
	.bmAttributes = USB_ENDPOINT_XFER_BULK,
	},
	},
	.hs_count = htole32(3),
	.hs_descs = {
	.intf = {
	.bLength = sizeof(descriptors.hs_descs.intf),
	.bDescriptorType = USB_DT_INTERFACE,
	.bNumEndpoints = 2,
	.bInterfaceClass = USB_CLASS_VENDOR_SPEC,
	.iInterface = 1,
	},
	.bulk_sink = {
	.bLength = sizeof(descriptors.hs_descs.bulk_sink),
	.bDescriptorType = USB_DT_ENDPOINT,
	.bEndpointAddress = 1 \| USB_DIR_IN,
	.bmAttributes = USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize = htole16(512),
	},
	.bulk_source = {
	.bLength = sizeof(descriptors.hs_descs.bulk_source),
	.bDescriptorType = USB_DT_ENDPOINT,
	.bEndpointAddress = 2 \| USB_DIR_OUT,
	.bmAttributes = USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize = htole16(512),
	},
	},
	};

	#define STR_INTERFACE "AIO Test"

	static const struct {
	struct usb_functionfs_strings_head header;
	struct {
	__le16 code;
	const char str1[sizeof(STR_INTERFACE)];
	} __attribute__ ((__packed__)) lang0;
	} __attribute__ ((__packed__)) strings = {
	.header = {
	.magic = htole32(FUNCTIONFS_STRINGS_MAGIC),
	.length = htole32(sizeof(strings)),
	.str_count = htole32(1),
	.lang_count = htole32(1),
	},
	.lang0 = {
	htole16(0x0409), /* en-us */
	STR_INTERFACE,
	},
	};

	/******************** Buffer structure *****************************/

	struct io_buffer {
	struct iocb **iocb;
	unsigned char **buf;
	unsigned cnt;
	unsigned len;
	unsigned requested;
	};

	/****************** Endpoints handling *****************************/

	static void display_event(struct usb_functionfs_event *event)
	{
	static const char *const names[] = {
	[FUNCTIONFS_BIND] = "BIND",
	[FUNCTIONFS_UNBIND] = "UNBIND",
	[FUNCTIONFS_ENABLE] = "ENABLE",
	[FUNCTIONFS_DISABLE] = "DISABLE",
	[FUNCTIONFS_SETUP] = "SETUP",
	[FUNCTIONFS_SUSPEND] = "SUSPEND",
	[FUNCTIONFS_RESUME] = "RESUME",
	};
	switch (event->type) {
	case FUNCTIONFS_BIND:
	case FUNCTIONFS_UNBIND:
	case FUNCTIONFS_ENABLE:
	case FUNCTIONFS_DISABLE:
	case FUNCTIONFS_SETUP:
	case FUNCTIONFS_SUSPEND:
	case FUNCTIONFS_RESUME:
	printf("Event %s\n", names[event->type]);
	}
	}

	static void handle_ep0(int ep0, bool *ready)
	{
	int ret;
	struct usb_functionfs_event event;

	ret = read(ep0, &event, sizeof(event));
	if (!ret) {
	perror("unable to read event from ep0");
	return;
	}
	display_event(&event);
	switch (event.type) {
	case FUNCTIONFS_SETUP:
	if (event.u.setup.bRequestType & USB_DIR_IN)
	write(ep0, NULL, 0);
	else
	read(ep0, NULL, 0);
	break;

	case FUNCTIONFS_ENABLE:
	*ready = true;
	break;

	case FUNCTIONFS_DISABLE:
	*ready = false;
	break;

	default:
	break;
	}
	}

	void init_bufs(struct io_buffer *iobuf, unsigned n, unsigned len)
	{
	unsigned i;
	iobuf->buf = malloc(nsizeof(iobuf->buf));
	iobuf->iocb = malloc(nsizeof(iobuf->iocb));
	iobuf->cnt = n;
	iobuf->len = len;
	iobuf->requested = 0;
	for (i = 0; i < n; ++i) {
	iobuf->buf[i] = malloc(lensizeof(*iobuf->buf));
	iobuf->iocb[i] = malloc(sizeof(**iobuf->iocb));
	}
	iobuf->cnt = n;
	}

	void delete_bufs(struct io_buffer *iobuf)
	{
	unsigned i;
	for (i = 0; i < iobuf->cnt; ++i) {
	free(iobuf->buf[i]);
	free(iobuf->iocb[i]);
	}
	free(iobuf->buf);
	free(iobuf->iocb);
	}

	int main(int argc, char *argv[])
	{
	int ret;
	unsigned i, j;
	char *ep_path;

	int ep0, ep1;

	io_context_t ctx;

	int evfd;
	fd_set rfds;

	struct io_buffer iobuf[2];
	int actual = 0;
	bool ready;

	if (argc != 2) {
	printf("ffs directory not specified!\n");
	return 1;
	}

	ep_path = malloc(strlen(argv[1]) + 4 /* "/ep#" / + 1 / '\0' */);
	if (!ep_path) {
	perror("malloc");
	return 1;
	}

	/* open endpoint files */
	sprintf(ep_path, "%s/ep0", argv[1]);
	ep0 = open(ep_path, O_RDWR);
	if (ep0 < 0) {
	perror("unable to open ep0");
	return 1;
	}
	if (write(ep0, &descriptors, sizeof(descriptors)) < 0) {
	perror("unable do write descriptors");
	return 1;
	}
	if (write(ep0, &strings, sizeof(strings)) < 0) {
	perror("unable to write strings");
	return 1;
	}
	sprintf(ep_path, "%s/ep1", argv[1]);
	ep1 = open(ep_path, O_RDWR);
	if (ep1 < 0) {
	perror("unable to open ep1");
	return 1;
	}

	free(ep_path);

	memset(&ctx, 0, sizeof(ctx));
	/* setup aio context to handle up to AIO_MAX requests */
	if (io_setup(AIO_MAX, &ctx) < 0) {
	perror("unable to setup aio");
	return 1;
	}

	evfd = eventfd(0, 0);
	if (evfd < 0) {
	perror("unable to open eventfd");
	return 1;
	}

	for (i = 0; i < sizeof(iobuf)/sizeof(*iobuf); ++i)
	init_bufs(&iobuf[i], BUFS_MAX, BUF_LEN);

	while (1) {
	FD_ZERO(&rfds);
	FD_SET(ep0, &rfds);
	FD_SET(evfd, &rfds);

	ret = select(((ep0 > evfd) ? ep0 : evfd)+1,
	&rfds, NULL, NULL, NULL);
	if (ret < 0) {
	if (errno == EINTR)
	continue;
	perror("select");
	break;
	}

	if (FD_ISSET(ep0, &rfds))
	handle_ep0(ep0, &ready);

	/* we are waiting for function ENABLE */
	if (!ready)
	continue;

	/*
	* when we're preparing new data to submit,
	* second buffer being transmitted
	*/
	for (i = 0; i < sizeof(iobuf)/sizeof(*iobuf); ++i) {
	if (iobuf[i].requested)
	continue;
	/* prepare requests */
	for (j = 0; j < iobuf[i].cnt; ++j) {
	io_prep_pwrite(iobuf[i].iocb[j], ep1,
	iobuf[i].buf[j],
	iobuf[i].len, 0);
	/* enable eventfd notification */
	iobuf[i].iocb[j]->u.c.flags \|= IOCB_FLAG_RESFD;
	iobuf[i].iocb[j]->u.c.resfd = evfd;
	}
	/* submit table of requests */
	ret = io_submit(ctx, iobuf[i].cnt, iobuf[i].iocb);
	if (ret >= 0) {
	iobuf[i].requested = ret;
	printf("submit: %d requests buf: %d\n", ret, i);
	} else
	perror("unable to submit requests");
	}

	/* if event is ready to read */
	if (!FD_ISSET(evfd, &rfds))
	continue;

	uint64_t ev_cnt;
	ret = read(evfd, &ev_cnt, sizeof(ev_cnt));
	if (ret < 0) {
	perror("unable to read eventfd");
	break;
	}

	struct io_event e[BUFS_MAX];
	/* we read aio events */
	ret = io_getevents(ctx, 1, BUFS_MAX, e, NULL);
	if (ret > 0) /* if we got events */
	iobuf[actual].requested -= ret;

	/* if all req's from iocb completed */
	if (!iobuf[actual].requested)
	actual = (actual + 1)%(sizeof(iobuf)/sizeof(*iobuf));
	}

	/* free resources */

	for (i = 0; i < sizeof(iobuf)/sizeof(*iobuf); ++i)
	delete_bufs(&iobuf[i]);
	io_destroy(ctx);

	close(ep1);
	close(ep0);

	return 0;
	}