LKML Archive on
help / color / mirror / Atom feed
From: Christoph Hellwig <>
To: Peter Zijlstra <>
Subject: Re: [Fwd: [PATCH 2/7] lock_list: a fine grain locked double linked list]
Date: Sun, 28 Jan 2007 17:20:27 +0000	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <1169999597.10987.33.camel@lappy>

> Provide a simple fine grain locked double link list.
> It is build upon the regular double linked list primitives, spinlocks and RCU.
> Locking is peculiar in that edges are locked, this avoid the circular lock
> dependancy created by the fact that the regular linked lists are circular.
> Item deletion requires that both surrounding elements are locked, however since
> the locking rules dictate that we lock elements in a single direction we have
> to lock the previous element while it might be deleted under us. Hence the
> requirement that all elements are RCU freed.

I think implicitly locked data structures are very bad for code readability
and debugability.  What's even worse here is that we have a requirement that
all members are RCU freed.

Note that we also have another implicitly locked (and refcounted) list
implementation in klist.[ch] - if we find consensus that we want implicitly
locked list we should figure out whether we want lock_list or klist semantics
and stick to one of them.

What uses do you have planned for this data structure?  In general I think
we'd be better off to simplify the data structures as in my files_list_lock
proposal instead of complicating the locking.

  reply	other threads:[~2007-01-28 17:20 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-28 15:53 Peter Zijlstra
2007-01-28 17:20 ` Christoph Hellwig [this message]
2007-01-29 10:20   ` Peter Zijlstra
2007-01-29 10:25     ` Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \
    --subject='Re: [Fwd: [PATCH 2/7] lock_list: a fine grain locked double linked list]' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).