LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Josh Triplett <josh@joshtriplett.org>
To: NeilBrown <neilb@suse.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Trond Myklebust <trond.myklebust@primarydata.com>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	linux-nfs@vger.kernel.org, Lai Jiangshan <jiangshanlai@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/4] rculist: add list_for_each_entry_from_rcu()
Date: Sun, 29 Apr 2018 22:20:33 -0700	[thread overview]
Message-ID: <20180430052032.GA16963@localhost> (raw)
In-Reply-To: <152506269061.7246.13075216914692813995.stgit@noble>

On Mon, Apr 30, 2018 at 02:31:30PM +1000, NeilBrown wrote:
> list_for_each_entry_from_rcu() is an RCU version of
> list_for_each_entry_from().  It walks a linked list under rcu
> protection, from a given start point.
> 
> It is similar to list_for_each_entry_continue_rcu() but starts *at*
> the given position rather than *after* it.
> 
> Naturally, the start point must be known to be in the list.

I'd suggest giving an explicit advisory comment to clarify and suggest
correct usage:

"This would typically require either that you obtained the node from a
previous walk of the list in the same RCU read-side critical section, or
that you held some sort of non-RCU reference (such as a reference count)
to keep the node alive *and* in the list."

(Feel free to wordsmith the exact wording, but something like that seems
like it would help people understand how to use this correctly, and make
it less likely that they'd use it incorrectly.)

  reply	other threads:[~2018-04-30  5:49 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-30  4:31 [PATCH 0/4 V2] Avoid quadratic search when freeing delegations NeilBrown
2018-04-30  4:31 ` [PATCH 3/4] rculist: add list_for_each_entry_from_rcu() NeilBrown
2018-04-30  5:20   ` Josh Triplett [this message]
2018-04-30 13:43     ` Paul E. McKenney
2018-04-30 15:14       ` Steven Rostedt
2018-04-30 15:35         ` Paul E. McKenney
2018-05-01  3:11           ` [PATCH 3/4 v2] " NeilBrown
2018-05-01 14:14             ` Paul E. McKenney
2018-05-01 21:34               ` NeilBrown
2018-04-30  4:31 ` [PATCH 1/4] NFS: slight optimization for walking list for delegations NeilBrown
2018-04-30 15:17   ` Steven Rostedt
2018-05-31  5:23     ` [PATCH 1/4 v2] " NeilBrown
2018-06-04 21:31       ` Steven Rostedt
2018-04-30  4:31 ` [PATCH 2/4] NFS: use cond_resched() when restarting walk of delegation list NeilBrown
2018-04-30  4:31 ` [PATCH 4/4] NFS: Avoid quadratic search when freeing delegations NeilBrown

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:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

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

  git send-email \
    --in-reply-to=20180430052032.GA16963@localhost \
    --to=josh@joshtriplett.org \
    --cc=anna.schumaker@netapp.com \
    --cc=jiangshanlai@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-nfs@vger.kernel.org \
    --cc=mathieu.desnoyers@efficios.com \
    --cc=neilb@suse.com \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=rostedt@goodmis.org \
    --cc=trond.myklebust@primarydata.com \
    --subject='Re: [PATCH 3/4] rculist: add list_for_each_entry_from_rcu()' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* 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).