From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751401AbeEAVfM (ORCPT ); Tue, 1 May 2018 17:35:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:43545 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751079AbeEAVfL (ORCPT ); Tue, 1 May 2018 17:35:11 -0400 From: NeilBrown To: paulmck@linux.vnet.ibm.com Date: Wed, 02 May 2018 07:34:56 +1000 Cc: Steven Rostedt , Josh Triplett , Trond Myklebust , Mathieu Desnoyers , Anna Schumaker , linux-nfs@vger.kernel.org, Lai Jiangshan , linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4 v2] rculist: add list_for_each_entry_from_rcu() In-Reply-To: <20180501141404.GD26088@linux.vnet.ibm.com> References: <152506256513.7246.13171564155614823841.stgit@noble> <152506269061.7246.13075216914692813995.stgit@noble> <20180430052032.GA16963@localhost> <20180430134308.GT26088@linux.vnet.ibm.com> <20180430111454.722c2aa8@gandalf.local.home> <20180430153505.GW26088@linux.vnet.ibm.com> <87y3h4gjdq.fsf@notabene.neil.brown.name> <20180501141404.GD26088@linux.vnet.ibm.com> Message-ID: <87vac7giv3.fsf@notabene.neil.brown.name> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Tue, May 01 2018, Paul E. McKenney wrote: > On Tue, May 01, 2018 at 01:11:29PM +1000, NeilBrown wrote: >>=20 >> 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. >>=20 >> It is similar to list_for_each_entry_continue_rcu() but starts *at* >> the given position rather than *after* it. >>=20 >> Naturally, the start point must be known to be in the list. >>=20 >> Also update the documentation for list_for_each_entry_continue_rcu() >> to match the documentation for the new list_for_each_entry_from_rcu(), >> and add list_for_each_entry_from_rcu() and the already existing >> hlist_for_each_entry_from_rcu() to section 7 of whatisRCU.txt. >>=20 >> Signed-off-by: NeilBrown > > I am guessing that it would be more convenient for you to carry this > with the patches using it, so: > > Reviewed-by: Paul E. McKenney Thanks Paul, yes I do hope this patch will go in with the other NFS patches. I'll wait to see what Trond and Anna think before proceeding with anything myself. Thanks a lot, NeilBrown > > If not, please let me know. > > Thanx, Paul > >> --- >> Documentation/RCU/whatisRCU.txt | 2 ++ >> include/linux/rculist.h | 32 +++++++++++++++++++++++++++++++- >> 2 files changed, 33 insertions(+), 1 deletion(-) >>=20 >> diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisR= CU.txt >> index a27fbfb0efb8..b7d38bd212d2 100644 >> --- a/Documentation/RCU/whatisRCU.txt >> +++ b/Documentation/RCU/whatisRCU.txt >> @@ -814,11 +814,13 @@ RCU list traversal: >> list_next_rcu >> list_for_each_entry_rcu >> list_for_each_entry_continue_rcu >> + list_for_each_entry_from_rcu >> hlist_first_rcu >> hlist_next_rcu >> hlist_pprev_rcu >> hlist_for_each_entry_rcu >> hlist_for_each_entry_rcu_bh >> + hlist_for_each_entry_from_rcu >> hlist_for_each_entry_continue_rcu >> hlist_for_each_entry_continue_rcu_bh >> hlist_nulls_first_rcu >> diff --git a/include/linux/rculist.h b/include/linux/rculist.h >> index 127f534fec94..4786c2235b98 100644 >> --- a/include/linux/rculist.h >> +++ b/include/linux/rculist.h >> @@ -396,13 +396,43 @@ static inline void list_splice_tail_init_rcu(struc= t list_head *list, >> * @member: the name of the list_head within the struct. >> * >> * Continue to iterate over list of given type, continuing after >> - * the current position. >> + * the current position which must have been in the list when the RCU r= ead >> + * lock was taken. >> + * 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 co= unt) >> + * to keep the node alive *and* in the list. >> + * >> + * This iterator is similar to list_for_each_entry_from_rcu() except >> + * this starts after the given position and that one starts at the given >> + * position. >> */ >> #define list_for_each_entry_continue_rcu(pos, head, member) \ >> for (pos =3D list_entry_rcu(pos->member.next, typeof(*pos), member); \ >> &pos->member !=3D (head); \ >> pos =3D list_entry_rcu(pos->member.next, typeof(*pos), member)) >>=20=20 >> +/** >> + * list_for_each_entry_from_rcu - iterate over a list from current point >> + * @pos: the type * to use as a loop cursor. >> + * @head: the head for your list. >> + * @member: the name of the list_node within the struct. >> + * >> + * Iterate over the tail of a list starting from a given position, >> + * which must have been in the list when the RCU read lock was taken. >> + * 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 co= unt) >> + * to keep the node alive *and* in the list. >> + * >> + * This iterator is similar to list_for_each_entry_continue_rcu() except >> + * this starts from the given position and that one starts from the pos= ition >> + * after the given position. >> + */ >> +#define list_for_each_entry_from_rcu(pos, head, member) \ >> + for (; &(pos)->member !=3D (head); \ >> + pos =3D list_entry_rcu(pos->member.next, typeof(*(pos)), member)) >> + >> /** >> * hlist_del_rcu - deletes entry from hash list without re-initializati= on >> * @n: the element to delete from the hash list. >> --=20 >> 2.14.0.rc0.dirty >>=20 --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAlro3YAACgkQOeye3VZi gbn1cg/7B/lreIqWbpbNaUQLBofW0qaNYU+036XvxxEOioH0KIjJUlEGPlTQXAMf 6+CQzRZxDv40yY9Qhplmt+7NzKlwtmE0CKX91vA7eVBPsvEj4yMb+WtUFC3g84hP eqZW7E6KLMIT4WutuuuBnB0C6MIGvaNyRGZkZEEBdJKvCgsOjUEIuo7rrI0Vk5pR YALDOvoUgacG1zO43UFKLXTJOcRDX+2Rkaa8zxEGZbkdCA2CayqqYAhKbaDKNv+S WZM6C5+c/NKWqwug0g8u/7pu0RuAK1j87NSRQUwwvFYbK9LybNgI2dUjTBLbN8Zu xdI3yEnNIvxLi4Al2LgxwgcIuNgjabl60DYDaArIfTKDsW2mQphQU7X7A89JpnAP pesmeaaM4BeHrP6WMl3Ntl9jhYc+qupS3vgJLdiiMPHTbtqVw8Af+I9g+ieQMft2 j5936wSi6ES75qLAUrkWCEHSAZlPf4Uxaf8j1fjP9CdKvLGPanNz/VCAtb2ibvuf luprWq3JM2dT24hvZHhUSs4SvYizs3RFBdpbBH8fF5GoEC6Jg0d7i9ByVuaRKATi ZWMxRhsPw4hNs7DuQA4EnG91XskC9yk/b+Ri/Ma/GXTJVENDne+6Px4OqS4gsiDB lThL/T6+1xFKPgcPmWzX0szTt0iu0nrZ9Fwe70k0+c9OhWZx2u0= =UHW1 -----END PGP SIGNATURE----- --=-=-=--