mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-24 05:04:00 +08:00
9c3060bedd
This is an example about how to add eventfd support to the current KAIO code, in order to enable KAIO to post readiness events to a pollable fd (hence compatible with POSIX select/poll). The KAIO code simply signals the eventfd fd when events are ready, and this triggers a POLLIN in the fd. This patch uses a reserved for future use member of the struct iocb to pass an eventfd file descriptor, that KAIO will use to post events every time a request completes. At that point, an aio_getevents() will return the completed result to a struct io_event. I made a quick test program to verify the patch, and it runs fine here: http://www.xmailserver.org/eventfd-aio-test.c The test program uses poll(2), but it'd, of course, work with select and epoll too. This can allow to schedule both block I/O and other poll-able devices requests, and wait for results using select/poll/epoll. In a typical scenario, an application would submit KAIO request using aio_submit(), and will also use epoll_ctl() on the whole other class of devices (that with the addition of signals, timers and user events, now it's pretty much complete), and then would: epoll_wait(...); for_each_event { if (curr_event_is_kaiofd) { aio_getevents(); dispatch_aio_events(); } else { dispatch_epoll_event(); } } Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
111 lines
3.0 KiB
C
111 lines
3.0 KiB
C
/* include/linux/aio_abi.h
|
|
*
|
|
* Copyright 2000,2001,2002 Red Hat.
|
|
*
|
|
* Written by Benjamin LaHaise <bcrl@kvack.org>
|
|
*
|
|
* Distribute under the terms of the GPLv2 (see ../../COPYING) or under
|
|
* the following terms.
|
|
*
|
|
* Permission to use, copy, modify, and distribute this software and its
|
|
* documentation is hereby granted, provided that the above copyright
|
|
* notice appears in all copies. This software is provided without any
|
|
* warranty, express or implied. Red Hat makes no representations about
|
|
* the suitability of this software for any purpose.
|
|
*
|
|
* IN NO EVENT SHALL RED HAT BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
|
|
* SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF
|
|
* THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF RED HAT HAS BEEN ADVISED
|
|
* OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
* RED HAT DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
* PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND
|
|
* RED HAT HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
|
|
* ENHANCEMENTS, OR MODIFICATIONS.
|
|
*/
|
|
#ifndef __LINUX__AIO_ABI_H
|
|
#define __LINUX__AIO_ABI_H
|
|
|
|
#include <asm/byteorder.h>
|
|
|
|
typedef unsigned long aio_context_t;
|
|
|
|
enum {
|
|
IOCB_CMD_PREAD = 0,
|
|
IOCB_CMD_PWRITE = 1,
|
|
IOCB_CMD_FSYNC = 2,
|
|
IOCB_CMD_FDSYNC = 3,
|
|
/* These two are experimental.
|
|
* IOCB_CMD_PREADX = 4,
|
|
* IOCB_CMD_POLL = 5,
|
|
*/
|
|
IOCB_CMD_NOOP = 6,
|
|
IOCB_CMD_PREADV = 7,
|
|
IOCB_CMD_PWRITEV = 8,
|
|
};
|
|
|
|
/*
|
|
* Valid flags for the "aio_flags" member of the "struct iocb".
|
|
*
|
|
* IOCB_FLAG_RESFD - Set if the "aio_resfd" member of the "struct iocb"
|
|
* is valid.
|
|
*/
|
|
#define IOCB_FLAG_RESFD (1 << 0)
|
|
|
|
/* read() from /dev/aio returns these structures. */
|
|
struct io_event {
|
|
__u64 data; /* the data field from the iocb */
|
|
__u64 obj; /* what iocb this event came from */
|
|
__s64 res; /* result code for this event */
|
|
__s64 res2; /* secondary result */
|
|
};
|
|
|
|
#if defined(__LITTLE_ENDIAN)
|
|
#define PADDED(x,y) x, y
|
|
#elif defined(__BIG_ENDIAN)
|
|
#define PADDED(x,y) y, x
|
|
#else
|
|
#error edit for your odd byteorder.
|
|
#endif
|
|
|
|
/*
|
|
* we always use a 64bit off_t when communicating
|
|
* with userland. its up to libraries to do the
|
|
* proper padding and aio_error abstraction
|
|
*/
|
|
|
|
struct iocb {
|
|
/* these are internal to the kernel/libc. */
|
|
__u64 aio_data; /* data to be returned in event's data */
|
|
__u32 PADDED(aio_key, aio_reserved1);
|
|
/* the kernel sets aio_key to the req # */
|
|
|
|
/* common fields */
|
|
__u16 aio_lio_opcode; /* see IOCB_CMD_ above */
|
|
__s16 aio_reqprio;
|
|
__u32 aio_fildes;
|
|
|
|
__u64 aio_buf;
|
|
__u64 aio_nbytes;
|
|
__s64 aio_offset;
|
|
|
|
/* extra parameters */
|
|
__u64 aio_reserved2; /* TODO: use this for a (struct sigevent *) */
|
|
|
|
/* flags for the "struct iocb" */
|
|
__u32 aio_flags;
|
|
|
|
/*
|
|
* if the IOCB_FLAG_RESFD flag of "aio_flags" is set, this is an
|
|
* eventfd to signal AIO readiness to
|
|
*/
|
|
__u32 aio_resfd;
|
|
}; /* 64 bytes */
|
|
|
|
#undef IFBIG
|
|
#undef IFLITTLE
|
|
|
|
#endif /* __LINUX__AIO_ABI_H */
|
|
|