65a311fcb2
Add a MOD_QUIESCE event for modules. This should return error (EBUSY) of the module is in use. MOD_UNLOAD should now only fail if it is impossible (as opposed to inconvenient) to unload the module. Valid reasons are memory references into the module which cannot be tracked down and eliminated. When kldunloading, we abandon if MOD_UNLOAD fails, and if -force is not given, MOD_QUIESCE failing will also prevent the unload. For backwards compatibility, we treat EOPNOTSUPP from MOD_QUIESCE as success. Document that modules should return EOPNOTSUPP for unknown events.
113 lines
3.3 KiB
Groff
113 lines
3.3 KiB
Groff
.\" -*- nroff -*-
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.\"
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.\" Copyright (c) 2000 Alexander Langer
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.\"
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.\" All rights reserved.
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.\"
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.\" This program is free software.
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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, 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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd March 1, 2001
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.Dt MODULE 9
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.Os
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.Sh NAME
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.Nm module
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.Nd structure describing a kernel module
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.Sh DESCRIPTION
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Each module in the kernel is described by a
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.Vt module_t
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structure.
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The structure contains the name of the device, a unique ID number,
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a pointer to an event handler function and to an argument,
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which is given to the event handler,
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as well as some kernel internal data.
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.Pp
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The
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.Xr DECLARE_MODULE 9
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macro
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registers the module with the system.
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.Pp
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When the module is loaded, the event handler function is called with
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the
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.Fa what
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argument set to
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.Dv MOD_LOAD .
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.Pp
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On unload it is first called with
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.Fa what
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set to MOD_QUIESCE .
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If the unload was not forced, a non-zero return will prevent the
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unload from happening.
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.Pp
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If the unload continues
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.Fa what
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is set to
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.Dv MOD_UNLOAD .
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If the module returns non-zero to this, the unload will not happen.
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.Pp
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The difference between MOD_QUIESCE and MOD_UNLOAD is that the module
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should fail MOD_QUIESCE if it is currently in use, whereas MOD_UNLOAD
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should only fail if it is impossible to unload the module, for instance
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because there are memory references to the module which cannot be revoked.
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.Pp
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When the system is shutting down,
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.Fa what
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contains the value of
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.Dv MOD_SHUTDOWN .
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.Pp
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The module should return EOPNOTSUPP for unrecognized values of
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.Fa what .
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.Sh EXAMPLES
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.Bd -literal
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/module.h>
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static int foo_handler(module_t mod, int /*modeventtype_t*/ what,
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void *arg);
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static moduledata_t mod_data= {
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"foo",
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foo_handler,
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0
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};
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MODULE_VERSION(foo, 1);
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MODULE_DEPEND(foo, bar, 1, 3, 4);
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DECLARE_MODULE(foo, mod_data, SI_SUB_EXEC, SI_ORDER_ANY);
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.Ed
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.Sh SEE ALSO
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.Xr DECLARE_MODULE 9 ,
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.Xr DEV_MODULE 9 ,
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.Xr DRIVER_MODULE 9 ,
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.Xr MODULE_DEPEND 9 ,
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.Xr MODULE_VERSION 9 ,
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.Xr SYSCALL_MODULE 9
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.Pp
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.Pa /usr/share/examples/kld
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.Sh AUTHORS
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This man page was written by
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.An Alexander Langer Aq alex@FreeBSD.org .
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