From: "David S. Miller" <davem@redhat.com>
To: Mitchell Blank Jr <mitch@sfgoth.com>
Cc: chas3@users.sourceforge.net, chas@cmf.nrl.navy.mil, netdev@oss.sgi.com
Subject: Re: [RFC] add rtnl semaphore to linux-atm
Date: Fri, 3 Oct 2003 22:16:40 -0700 [thread overview]
Message-ID: <20031003221640.19aa485f.davem@redhat.com> (raw)
In-Reply-To: <20031003214541.GA73152@gaz.sfgoth.com>
On Fri, 3 Oct 2003 14:45:41 -0700
Mitchell Blank Jr <mitch@sfgoth.com> wrote:
> We *can't* use it to protect the state of the vcc list though because we
> need to do lookups in both interrupt and bh context. Using a sleeping
> lock alone is a non-starter.
>
> That's why we need to do the three-step spinlock->semaphore->spinlock
> dance in the vcc open and close paths.
The semaphore protects "modifications", it basically serializes them.
You still need a rwlock to protect the actual lists and this rwlock
is what the interrupt/bh context code takes to traverse the lists
and tables.
This is how the netdev list works, for example.
next prev parent reply other threads:[~2003-10-04 5:16 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-10-01 11:34 [RFC] add rtnl semaphore to linux-atm chas williams
2003-10-01 12:42 ` David S. Miller
2003-10-01 13:07 ` chas williams
2003-10-01 13:14 ` David S. Miller
2003-10-03 2:26 ` Mitchell Blank Jr
2003-10-03 13:58 ` David S. Miller
2003-10-03 21:45 ` Mitchell Blank Jr
2003-10-04 5:16 ` David S. Miller [this message]
2003-10-04 5:55 ` Mitchell Blank Jr
2003-10-04 6:56 ` Mitchell Blank Jr
2003-10-04 6:59 ` Mitchell Blank Jr
2003-10-04 12:50 ` chas williams
2003-10-04 19:42 ` Mitchell Blank Jr
2003-10-05 12:52 ` chas williams
2003-10-06 9:03 ` Mitchell Blank Jr
2003-10-06 14:46 ` chas williams
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