Re: Another idea for simplifying locking in kernel/module.c

Andre Hedrick (andre@linux-ide.org)
Fri, 10 Jan 2003 01:38:56 -0800 (PST)


I'll bite .... what the flip is [unsafe] ??

On Fri, 10 Jan 2003, Adam J. Richter wrote:

> Rusty Russell wrote:
> >In message <200301070219.SAA12905@adam.yggdrasil.com> you write:
> >> Here is a way to replace all of the specialized "stop CPU"
> >> locking code in kernel/module.c with an rw_semaphore by using
> >> down_read_trylock in try_module_get() and down_write when beginning to
> >> unload the module.
>
> >And now you can't modularize netfilter modules.
>
> Why not? Last time you went looking in the networking code
> for an example of something that had to increment a module reference
> in a context where blocking was not allowed you ended up conceding
> that you example was incorrect. If you've now found an example,
> please let me know.
>
> I just booted my gateway machine to a kernel using my
> aforemetioned patch and various netfilter modules. I've surfed the
> web, FTP'ed file and run irc through it. It seems to be okay.
> Here is the lsmod listing from it.
>
> Module Size Used by
> iptable_nat 28324 1 [unsafe],
> ip_conntrack 39788 2 iptable_nat,[unsafe],
> ext2 60712 0 -
> pcmcia_core 55744 0 -
> i810 65816 0 -
> atkbd 6820 0 -
> i8042 8864 0 -
> serio 4564 2 atkbd,i8042,
> autofs 14992 1 -
> ipt_TCPMSS 3568 1 [unsafe],
> iptable_filter 2272 1 [unsafe],
> ip_tables 17296 8 iptable_nat,ipt_TCPMSS,iptable_filter,[unsafe],
> nfsd 111824 1 [unsafe],
> exportfs 6160 1 nfsd,
> nfs 132092 0 -
> lockd 58736 3 nfsd,nfs,[unsafe],
> sunrpc 114136 4 nfsd,nfs,lockd,[unsafe],
> pppoe 14336 1 [unsafe],
> pppox 3480 1 pppoe,
> af_packet 20760 2 [unsafe],
> ppp_async 11296 0 -
> ppp_generic 30264 5 pppoe,pppox,ppp_async,
> slhc 6576 1 ppp_generic,
> ipv4 392804 88 iptable_nat,ip_conntrack,sunrpc,af_packet,[unsafe],
> unix 23884 11 [unsafe],
> sis_agp 4224 0 -
> agpgart 23248 2 sis_agp,
> ohci_hcd 28400 0 -
> usbcore 101108 3 ohci_hcd,
> ac97_codec 12432 0 -
> sis900 16548 0 -
> tulip 52960 2 [unsafe],
> crc32 4272 2 sis900,tulip,
> ext3 112232 3 -
> jbd 65840 1 ext3,
> mbcache 7764 2 ext2,ext3,
> ide_disk 17332 5 -
> ide_mod 143684 1 ide_disk,[unsafe],
>
>
> Adam J. Richter __ ______________ 575 Oroville Road
> adam@yggdrasil.com \ / Milpitas, California 95035
> +1 408 309-6081 | g g d r a s i l United States of America
> "Free Software For The Rest Of Us."
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Andre Hedrick
LAD Storage Consulting Group

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