PR/38098 CVS commit: src/sys

[Andrew Doran <ad%netbsd.org@localhost>]

The following reply was made to PR kern/38098; it has been noted by GNATS.

From: Andrew Doran <ad%netbsd.org@localhost>
To: gnats-bugs%gnats.NetBSD.org@localhost
Cc: 
Subject: PR/38098 CVS commit: src/sys
Date: Fri, 21 Mar 2008 21:53:35 +0000 (UTC)

 Module Name:   src
 Committed By:  ad
 Date:          Fri Mar 21 21:53:35 UTC 2008
 
 Modified Files:
        src/sys/kern: kern_descrip.c kern_event.c
        src/sys/sys: event.h eventvar.h file.h filedesc.h
 Added Files:
        src/sys/kern: sys_descrip.c
 
 Log Message:
 File descriptor changes, discussed on tech-kern:
 
 - Redo reference counting to be sane.  LWPs accessing files take a short
   term reference on the local file descriptor.  This is the most common
   case.  While a file is in a process descriptor table, a reference is
   held to the file.  The file reference count only changes during control
   operations like open() or close().  Code that comes at files from an
   unusual direction (i.e. foreign to the process) like procfs or sysctl
   takes a reference on the file (f_count), and not on a descriptor.
 
 - Remove knowledge of reference counting and locking from most code that
   deals with files.
 
 - Make the usual case of file descriptor lookup lockless.
 
 - Make kqueue MP and MT safe. PR kern/38098, PR kern/38137.
 
 - Fix numerous file handling bugs, and bugs in the descriptor code that
   affected multithreaded processes.
 
 - Split descriptor system calls out into sys_descrip.c.
 
 - A few stylistic changes: KNF, remove unused casts now that caddr_t is
   gone. Replace dumb gotos with loop control in a few places.
 
 - Don't do redundant pointer passing (struct proc, lwp, filedesc *) unless
   the routine is likely to be inlined.  Most of the time it's about the
   current process.
 
 
 To generate a diff of this commit:
 cvs rdiff -r1.172 -r1.173 src/sys/kern/kern_descrip.c
 cvs rdiff -r1.48 -r1.49 src/sys/kern/kern_event.c
 cvs rdiff -r0 -r1.1 src/sys/kern/sys_descrip.c
 cvs rdiff -r1.19 -r1.20 src/sys/sys/event.h
 cvs rdiff -r1.7 -r1.8 src/sys/sys/eventvar.h
 cvs rdiff -r1.63 -r1.64 src/sys/sys/file.h
 cvs rdiff -r1.45 -r1.46 src/sys/sys/filedesc.h
 
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.