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If a multithreaded app closes an fd while another thread is blocked in
read/write/accept, then the expectation is that the blocked thread will
exit and the close complete.
Since only one fd is affected, but many fd can refer to the same file,
the close code can only request the fs code unblock with ERESTART.
Fixed for pipes and sockets, ERESTART will only be generated after such
a close - so there should be no change for other programs.
Also rename fo_abort() to fo_restart() (this used to be fo_drain()).
Fixes PR/26567

/* $NetBSD: pipe.h,v 1.32 2009/12/20 09:36:06 dsl Exp $ */

/*
 * Copyright (c) 1996 John S. Dyson
 * 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 immediately at the beginning of the file, without modification,
 *    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.
 * 3. Absolutely no warranty of function or purpose is made by the author
 *    John S. Dyson.
 * 4. This work was done expressly for inclusion into FreeBSD.  Other use
 *    is allowed if this notation is included.
 * 5. Modifications may be freely made to this file if the above conditions
 *    are met.
 *
 * $FreeBSD: src/sys/sys/pipe.h,v 1.18 2002/02/27 07:35:59 alfred Exp $
 */

#ifndef _SYS_PIPE_H_
#define _SYS_PIPE_H_

#include <sys/selinfo.h>		/* for struct selinfo */

#include <uvm/uvm_extern.h>

/*
 * Pipe buffer size, keep moderate in value, pipes take kva space.
 */
#ifndef PIPE_SIZE
#define PIPE_SIZE	16384
#endif

#ifndef BIG_PIPE_SIZE
#define BIG_PIPE_SIZE	(4*PIPE_SIZE)
#endif

/*
 * Maximum size of kva for direct write transfer. If the amount
 * of data in buffer is larger, it would be transferred in chunks of this
 * size. This kva memory is freed after use if amount of pipe kva memory
 * is bigger than limitpipekva.
 */
#ifndef PIPE_DIRECT_CHUNK
#define PIPE_DIRECT_CHUNK	(1*1024*1024)
#endif

/*
 * PIPE_MINDIRECT MUST be smaller than PIPE_SIZE and MUST be bigger
 * than PIPE_BUF.
 */
#ifndef PIPE_MINDIRECT
#define PIPE_MINDIRECT	8192
#endif

/*
 * Pipe buffer information.
 * Separate in, out, cnt are used to simplify calculations.
 * Buffered write is active when the buffer.cnt field is set.
 */
struct pipebuf {
	size_t	cnt;		/* number of chars currently in buffer */
	u_int	in;		/* in pointer */
	u_int	out;		/* out pointer */
	size_t	size;		/* size of buffer */
	void *	buffer;		/* kva of buffer */
};

/*
 * Information to support direct transfers between processes for pipes.
 */
struct pipemapping {
	vaddr_t		kva;		/* kernel virtual address */
	vsize_t		cnt;		/* number of chars in buffer */
	voff_t		pos;		/* current position within page */
	int		npages;		/* how many pages allocated */
	struct vm_page	**pgs;		/* pointers to the pages */
	u_int		egen;		/* emap generation number */
};

/*
 * Bits in pipe_state.
 */
#define PIPE_ASYNC	0x001	/* Async I/O */
#define PIPE_EOF	0x010	/* Pipe is in EOF condition */
#define PIPE_SIGNALR	0x020	/* Do selwakeup() on read(2) */
#define PIPE_DIRECTW	0x040	/* Pipe in direct write mode setup */
#define PIPE_DIRECTR	0x080	/* Pipe direct read request (setup complete) */
#define	PIPE_LOCKFL	0x100	/* Process has exclusive access to
				   pointers/data. */
#define	PIPE_LWANT	0x200	/* Process wants exclusive access to
				   pointers/data. */
#define	PIPE_RESTART	0x400	/* Return ERESTART to blocked syscalls */

/*
 * Per-pipe data structure.
 * Two of these are linked together to produce bi-directional pipes.
 */
struct pipe {
	kmutex_t *pipe_lock;		/* pipe mutex */
	kcondvar_t pipe_rcv;		/* cv for readers */
	kcondvar_t pipe_wcv;		/* cv for writers */
	kcondvar_t pipe_draincv;	/* cv for close */
	kcondvar_t pipe_lkcv;		/* locking */
	struct	pipebuf pipe_buffer;	/* data storage */
	struct	pipemapping pipe_map;	/* pipe mapping for direct I/O */
	struct	selinfo pipe_sel;	/* for compat with select */
	struct	timespec pipe_atime;	/* time of last access */
	struct	timespec pipe_mtime;	/* time of last modify */
	struct	timespec pipe_btime;	/* time of creation */
	pid_t	pipe_pgid;		/* process group for sigio */
	struct	pipe *pipe_peer;	/* link with other direction */
	u_int	pipe_state;		/* pipe status info */
	int	pipe_busy;		/* busy flag, to handle rundown */
	vaddr_t	pipe_kmem;		/* preallocated PIPE_SIZE buffer */
};

/*
 * KERN_PIPE subtypes
 */
#define	KERN_PIPE_MAXKVASZ		1	/* maximum kva size */
#define	KERN_PIPE_LIMITKVA		2	/* */
#define	KERN_PIPE_MAXBIGPIPES		3	/* maximum # of "big" pipes */
#define	KERN_PIPE_NBIGPIPES		4	/* current number of "big" p. */
#define	KERN_PIPE_KVASIZE		5	/* current pipe kva size */
#define	KERN_PIPE_MAXID			6

#define	CTL_PIPE_NAMES { \
	{ 0, 0 }, \
	{ "maxkvasz", CTLTYPE_INT }, \
	{ "maxloankvasz", CTLTYPE_INT }, \
	{ "maxbigpipes", CTLTYPE_INT }, \
	{ "nbigpipes", CTLTYPE_INT }, \
	{ "kvasize", CTLTYPE_INT }, \
}

#ifdef _KERNEL
int	sysctl_dopipe(int *, u_int, void *, size_t *, void *, size_t);
void	pipe_init(void);
#endif /* _KERNEL */

#endif /* !_SYS_PIPE_H_ */