741b6cf8a5
PIPE_MTX(). Since the pipe_present is cleared before (potentially) sleeping, the second thread may enter the pipeclose() for the reciprocal pipe end. The test at the end of the pipeclose() for the pipe_present == 0 would succeed, allowing the second thread to free the pipe memory. First threads then accesses the freed memory after being woken up. Properly track the closing state of the pipe in the pipe_present. Introduce the intermediate state that marks the pipe as mostly dismantled but might be sleeping waiting for the knote list to be cleared. Free the pipe pair memory only when both ends pass that point. Debugging help and tested by: pho Discussed with: jmg MFC after: 2 weeks
142 lines
4.2 KiB
C
142 lines
4.2 KiB
C
/*-
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* Copyright (c) 1996 John S. Dyson
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice immediately at the beginning of the file, without modification,
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* this list of conditions, and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Absolutely no warranty of function or purpose is made by the author
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* John S. Dyson.
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* 4. This work was done expressly for inclusion into FreeBSD. Other use
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* is allowed if this notation is included.
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* 5. Modifications may be freely made to this file if the above conditions
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* are met.
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*
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* $FreeBSD$
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*/
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#ifndef _SYS_PIPE_H_
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#define _SYS_PIPE_H_
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#ifndef _KERNEL
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#error "no user-servicable parts inside"
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#endif
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/*
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* Pipe buffer size, keep moderate in value, pipes take kva space.
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*/
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#ifndef PIPE_SIZE
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#define PIPE_SIZE 16384
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#endif
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#ifndef BIG_PIPE_SIZE
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#define BIG_PIPE_SIZE (64*1024)
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#endif
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#ifndef SMALL_PIPE_SIZE
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#define SMALL_PIPE_SIZE PAGE_SIZE
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#endif
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/*
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* PIPE_MINDIRECT MUST be smaller than PIPE_SIZE and MUST be bigger
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* than PIPE_BUF.
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*/
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#ifndef PIPE_MINDIRECT
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#define PIPE_MINDIRECT 8192
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#endif
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#define PIPENPAGES (BIG_PIPE_SIZE / PAGE_SIZE + 1)
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/*
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* See sys_pipe.c for info on what these limits mean.
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*/
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extern int maxpipekva;
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/*
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* Pipe buffer information.
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* Separate in, out, cnt are used to simplify calculations.
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* Buffered write is active when the buffer.cnt field is set.
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*/
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struct pipebuf {
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u_int cnt; /* number of chars currently in buffer */
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u_int in; /* in pointer */
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u_int out; /* out pointer */
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u_int size; /* size of buffer */
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caddr_t buffer; /* kva of buffer */
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};
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/*
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* Information to support direct transfers between processes for pipes.
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*/
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struct pipemapping {
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vm_size_t cnt; /* number of chars in buffer */
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vm_size_t pos; /* current position of transfer */
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int npages; /* number of pages */
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vm_page_t ms[PIPENPAGES]; /* pages in source process */
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};
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/*
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* Bits in pipe_state.
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*/
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#define PIPE_ASYNC 0x004 /* Async? I/O. */
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#define PIPE_WANTR 0x008 /* Reader wants some characters. */
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#define PIPE_WANTW 0x010 /* Writer wants space to put characters. */
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#define PIPE_WANT 0x020 /* Pipe is wanted to be run-down. */
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#define PIPE_SEL 0x040 /* Pipe has a select active. */
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#define PIPE_EOF 0x080 /* Pipe is in EOF condition. */
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#define PIPE_LOCKFL 0x100 /* Process has exclusive access to pointers/data. */
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#define PIPE_LWANT 0x200 /* Process wants exclusive access to pointers/data. */
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#define PIPE_DIRECTW 0x400 /* Pipe direct write active. */
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#define PIPE_DIRECTOK 0x800 /* Direct mode ok. */
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/*
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* Per-pipe data structure.
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* Two of these are linked together to produce bi-directional pipes.
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*/
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struct pipe {
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struct pipebuf pipe_buffer; /* data storage */
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struct pipemapping pipe_map; /* pipe mapping for direct I/O */
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struct selinfo pipe_sel; /* for compat with select */
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struct timespec pipe_atime; /* time of last access */
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struct timespec pipe_mtime; /* time of last modify */
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struct timespec pipe_ctime; /* time of status change */
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struct sigio *pipe_sigio; /* information for async I/O */
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struct pipe *pipe_peer; /* link with other direction */
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struct pipepair *pipe_pair; /* container structure pointer */
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u_int pipe_state; /* pipe status info */
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int pipe_busy; /* busy flag, mostly to handle rundown sanely */
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int pipe_present; /* still present? */
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};
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/*
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* Values for the pipe_present.
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*/
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#define PIPE_ACTIVE 1
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#define PIPE_CLOSING 2
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#define PIPE_FINALIZED 3
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/*
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* Container structure to hold the two pipe endpoints, mutex, and label
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* pointer.
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*/
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struct pipepair {
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struct pipe pp_rpipe;
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struct pipe pp_wpipe;
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struct mtx pp_mtx;
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struct label *pp_label;
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};
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#define PIPE_MTX(pipe) (&(pipe)->pipe_pair->pp_mtx)
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#define PIPE_LOCK(pipe) mtx_lock(PIPE_MTX(pipe))
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#define PIPE_UNLOCK(pipe) mtx_unlock(PIPE_MTX(pipe))
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#define PIPE_LOCK_ASSERT(pipe, type) mtx_assert(PIPE_MTX(pipe), (type))
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#endif /* !_SYS_PIPE_H_ */
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