Date: Wed, 16 Dec 1998 11:50:58 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: zhihuizhang <bf20761@binghamton.edu> Cc: hackers <freebsd-hackers@FreeBSD.ORG> Subject: Re: Question on lock Message-ID: <199812161950.LAA81012@apollo.backplane.com> References: <Pine.SOL.L3.93.981216141324.15319A-100000@bingsun2>
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:In the comment of vm_map_pageable() in file vm_map.c, there is a following
:sentence:
:
:"Because of problems in the recursive lock package, we cannot upgrade to a
:write lock in vm_map_lookup."
:
:Does the recursive lock package refer to kern_lock.c? There IS a
:lock_read_to_write() call in vm_map_lookup(). So why there is such a
:problem? Please give me some enlightenment.
:
:Any help is appreciated.
There are probably deadlock problems associated with trying to upgrade
the lock at that point.
The whole locking methodology used in the kernel really needs a complete
rewrite.
-Matt
:--------------------------------------------------
:| Zhihui Zhang, http://cs.binghamton.edu/~zzhang |
:| Dept. of Computer Science, SUNY at Binghamton |
:--------------------------------------------------
:
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Matthew Dillon Engineering, HiWay Technologies, Inc. & BEST Internet
Communications & God knows what else.
<dillon@backplane.com> (Please include original email in any response)
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