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freebsd-dev/sys/sys/sockbuf.h
John Baldwin f3215338ef Refactor the AIO subsystem to permit file-type-specific handling and 
improve cancellation robustness.

Introduce a new file operation, fo_aio_queue, which is responsible for
queueing and completing an asynchronous I/O request for a given file.
The AIO subystem now exports library of routines to manipulate AIO
requests as well as the ability to run a handler function in the
"default" pool of AIO daemons to service a request.

A default implementation for file types which do not include an
fo_aio_queue method queues requests to the "default" pool invoking the
fo_read or fo_write methods as before.

The AIO subsystem permits file types to install a private "cancel"
routine when a request is queued to permit safe dequeueing and cleanup
of cancelled requests.

Sockets now use their own pool of AIO daemons and service per-socket
requests in FIFO order.  Socket requests will not block indefinitely
permitting timely cancellation of all requests.

Due to the now-tight coupling of the AIO subsystem with file types,
the AIO subsystem is now a standard part of all kernels.  The VFS_AIO
kernel option and aio.ko module are gone.

Many file types may block indefinitely in their fo_read or fo_write
callbacks resulting in a hung AIO daemon.  This can result in hung
user processes (when processes attempt to cancel all outstanding
requests during exit) or a hung system.  To protect against this, AIO
requests are only permitted for known "safe" files by default.  AIO
requests for all file types can be enabled by setting the new
vfs.aio.enable_usafe sysctl to a non-zero value.  The AIO tests have
been updated to skip operations on unsafe file types if the sysctl is
zero.

Currently, AIO requests on sockets and raw disks are considered safe
and are enabled by default.  aio_mlock() is also enabled by default.

Reviewed by:	cem, jilles
Discussed with:	kib (earlier version)
Sponsored by:	Chelsio Communications
Differential Revision:	https://reviews.freebsd.org/D5289
2016-03-01 18:12:14 +00:00

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/*-
* Copyright (c) 1982, 1986, 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)socketvar.h 8.3 (Berkeley) 2/19/95
*
* $FreeBSD$
*/
#ifndef _SYS_SOCKBUF_H_
#define _SYS_SOCKBUF_H_
#include <sys/selinfo.h> /* for struct selinfo */
#include <sys/_lock.h>
#include <sys/_mutex.h>
#include <sys/_sx.h>
#include <sys/_task.h>
#define SB_MAX (2*1024*1024) /* default for max chars in sockbuf */
/*
* Constants for sb_flags field of struct sockbuf.
*/
#define SB_WAIT 0x04 /* someone is waiting for data/space */
#define SB_SEL 0x08 /* someone is selecting */
#define SB_ASYNC 0x10 /* ASYNC I/O, need signals */
#define SB_UPCALL 0x20 /* someone wants an upcall */
#define SB_NOINTR 0x40 /* operations not interruptible */
#define SB_AIO 0x80 /* AIO operations queued */
#define SB_KNOTE 0x100 /* kernel note attached */
#define SB_NOCOALESCE 0x200 /* don't coalesce new data into existing mbufs */
#define SB_IN_TOE 0x400 /* socket buffer is in the middle of an operation */
#define SB_AUTOSIZE 0x800 /* automatically size socket buffer */
#define SB_STOP 0x1000 /* backpressure indicator */
#define SB_AIO_RUNNING 0x2000 /* AIO operation running */
#define SBS_CANTSENDMORE 0x0010 /* can't send more data to peer */
#define SBS_CANTRCVMORE 0x0020 /* can't receive more data from peer */
#define SBS_RCVATMARK 0x0040 /* at mark on input */
struct mbuf;
struct sockaddr;
struct socket;
struct thread;
struct xsockbuf {
u_int sb_cc;
u_int sb_hiwat;
u_int sb_mbcnt;
u_int sb_mcnt;
u_int sb_ccnt;
u_int sb_mbmax;
int sb_lowat;
int sb_timeo;
short sb_flags;
};
/*
* Variables for socket buffering.
*
* Locking key to struct sockbuf:
* (a) locked by SOCKBUF_LOCK().
*/
struct sockbuf {
struct selinfo sb_sel; /* process selecting read/write */
struct mtx sb_mtx; /* sockbuf lock */
struct sx sb_sx; /* prevent I/O interlacing */
short sb_state; /* (a) socket state on sockbuf */
#define sb_startzero sb_mb
struct mbuf *sb_mb; /* (a) the mbuf chain */
struct mbuf *sb_mbtail; /* (a) the last mbuf in the chain */
struct mbuf *sb_lastrecord; /* (a) first mbuf of last
* record in socket buffer */
struct mbuf *sb_sndptr; /* (a) pointer into mbuf chain */
struct mbuf *sb_fnrdy; /* (a) pointer to first not ready buffer */
u_int sb_sndptroff; /* (a) byte offset of ptr into chain */
u_int sb_acc; /* (a) available chars in buffer */
u_int sb_ccc; /* (a) claimed chars in buffer */
u_int sb_hiwat; /* (a) max actual char count */
u_int sb_mbcnt; /* (a) chars of mbufs used */
u_int sb_mcnt; /* (a) number of mbufs in buffer */
u_int sb_ccnt; /* (a) number of clusters in buffer */
u_int sb_mbmax; /* (a) max chars of mbufs to use */
u_int sb_ctl; /* (a) non-data chars in buffer */
int sb_lowat; /* (a) low water mark */
sbintime_t sb_timeo; /* (a) timeout for read/write */
short sb_flags; /* (a) flags, see below */
int (*sb_upcall)(struct socket *, void *, int); /* (a) */
void *sb_upcallarg; /* (a) */
TAILQ_HEAD(, kaiocb) sb_aiojobq; /* (a) pending AIO ops */
struct task sb_aiotask; /* AIO task */
};
#ifdef _KERNEL
/*
* Per-socket buffer mutex used to protect most fields in the socket
* buffer.
*/
#define SOCKBUF_MTX(_sb) (&(_sb)->sb_mtx)
#define SOCKBUF_LOCK_INIT(_sb, _name) \
mtx_init(SOCKBUF_MTX(_sb), _name, NULL, MTX_DEF)
#define SOCKBUF_LOCK_DESTROY(_sb) mtx_destroy(SOCKBUF_MTX(_sb))
#define SOCKBUF_LOCK(_sb) mtx_lock(SOCKBUF_MTX(_sb))
#define SOCKBUF_OWNED(_sb) mtx_owned(SOCKBUF_MTX(_sb))
#define SOCKBUF_UNLOCK(_sb) mtx_unlock(SOCKBUF_MTX(_sb))
#define SOCKBUF_LOCK_ASSERT(_sb) mtx_assert(SOCKBUF_MTX(_sb), MA_OWNED)
#define SOCKBUF_UNLOCK_ASSERT(_sb) mtx_assert(SOCKBUF_MTX(_sb), MA_NOTOWNED)
/*
* Socket buffer private mbuf(9) flags.
*/
#define M_NOTREADY M_PROTO1 /* m_data not populated yet */
#define M_BLOCKED M_PROTO2 /* M_NOTREADY in front of m */
#define M_NOTAVAIL (M_NOTREADY | M_BLOCKED)
void sbappend(struct sockbuf *sb, struct mbuf *m, int flags);
void sbappend_locked(struct sockbuf *sb, struct mbuf *m, int flags);
void sbappendstream(struct sockbuf *sb, struct mbuf *m, int flags);
void sbappendstream_locked(struct sockbuf *sb, struct mbuf *m, int flags);
int sbappendaddr(struct sockbuf *sb, const struct sockaddr *asa,
struct mbuf *m0, struct mbuf *control);
int sbappendaddr_locked(struct sockbuf *sb, const struct sockaddr *asa,
struct mbuf *m0, struct mbuf *control);
int sbappendaddr_nospacecheck_locked(struct sockbuf *sb,
const struct sockaddr *asa, struct mbuf *m0, struct mbuf *control);
int sbappendcontrol(struct sockbuf *sb, struct mbuf *m0,
struct mbuf *control);
int sbappendcontrol_locked(struct sockbuf *sb, struct mbuf *m0,
struct mbuf *control);
void sbappendrecord(struct sockbuf *sb, struct mbuf *m0);
void sbappendrecord_locked(struct sockbuf *sb, struct mbuf *m0);
void sbcompress(struct sockbuf *sb, struct mbuf *m, struct mbuf *n);
struct mbuf *
sbcreatecontrol(caddr_t p, int size, int type, int level);
void sbdestroy(struct sockbuf *sb, struct socket *so);
void sbdrop(struct sockbuf *sb, int len);
void sbdrop_locked(struct sockbuf *sb, int len);
struct mbuf *
sbcut_locked(struct sockbuf *sb, int len);
void sbdroprecord(struct sockbuf *sb);
void sbdroprecord_locked(struct sockbuf *sb);
void sbflush(struct sockbuf *sb);
void sbflush_locked(struct sockbuf *sb);
void sbrelease(struct sockbuf *sb, struct socket *so);
void sbrelease_internal(struct sockbuf *sb, struct socket *so);
void sbrelease_locked(struct sockbuf *sb, struct socket *so);
int sbreserve(struct sockbuf *sb, u_long cc, struct socket *so,
struct thread *td);
int sbreserve_locked(struct sockbuf *sb, u_long cc, struct socket *so,
struct thread *td);
struct mbuf *
sbsndptr(struct sockbuf *sb, u_int off, u_int len, u_int *moff);
struct mbuf *
sbsndmbuf(struct sockbuf *sb, u_int off, u_int *moff);
void sbtoxsockbuf(struct sockbuf *sb, struct xsockbuf *xsb);
int sbwait(struct sockbuf *sb);
int sblock(struct sockbuf *sb, int flags);
void sbunlock(struct sockbuf *sb);
void sballoc(struct sockbuf *, struct mbuf *);
void sbfree(struct sockbuf *, struct mbuf *);
int sbready(struct sockbuf *, struct mbuf *, int);
/*
* Return how much data is available to be taken out of socket
* buffer right now.
*/
static inline u_int
sbavail(struct sockbuf *sb)
{
#if 0
SOCKBUF_LOCK_ASSERT(sb);
#endif
return (sb->sb_acc);
}
/*
* Return how much data sits there in the socket buffer
* It might be that some data is not yet ready to be read.
*/
static inline u_int
sbused(struct sockbuf *sb)
{
#if 0
SOCKBUF_LOCK_ASSERT(sb);
#endif
return (sb->sb_ccc);
}
/*
* How much space is there in a socket buffer (so->so_snd or so->so_rcv)?
* This is problematical if the fields are unsigned, as the space might
* still be negative (ccc > hiwat or mbcnt > mbmax).
*/
static inline long
sbspace(struct sockbuf *sb)
{
int bleft, mleft; /* size should match sockbuf fields */
#if 0
SOCKBUF_LOCK_ASSERT(sb);
#endif
if (sb->sb_flags & SB_STOP)
return(0);
bleft = sb->sb_hiwat - sb->sb_ccc;
mleft = sb->sb_mbmax - sb->sb_mbcnt;
return ((bleft < mleft) ? bleft : mleft);
}
#define SB_EMPTY_FIXUP(sb) do { \
if ((sb)->sb_mb == NULL) { \
(sb)->sb_mbtail = NULL; \
(sb)->sb_lastrecord = NULL; \
} \
} while (/*CONSTCOND*/0)
#ifdef SOCKBUF_DEBUG
void sblastrecordchk(struct sockbuf *, const char *, int);
void sblastmbufchk(struct sockbuf *, const char *, int);
void sbcheck(struct sockbuf *, const char *, int);
#define SBLASTRECORDCHK(sb) sblastrecordchk((sb), __FILE__, __LINE__)
#define SBLASTMBUFCHK(sb) sblastmbufchk((sb), __FILE__, __LINE__)
#define SBCHECK(sb) sbcheck((sb), __FILE__, __LINE__)
#else
#define SBLASTRECORDCHK(sb) do {} while (0)
#define SBLASTMBUFCHK(sb) do {} while (0)
#define SBCHECK(sb) do {} while (0)
#endif /* SOCKBUF_DEBUG */
#endif /* _KERNEL */
#endif /* _SYS_SOCKBUF_H_ */
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