Return-Path: Received: from mx2.suse.de ([195.135.220.15]:58189 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753569AbeFREWt (ORCPT ); Mon, 18 Jun 2018 00:22:49 -0400 From: NeilBrown To: paulmck@linux.vnet.ibm.com Date: Mon, 18 Jun 2018 14:22:40 +1000 Cc: Linus Torvalds , trondmy@hammerspace.com, Linux Kernel Mailing List , Linux NFS Mailing List Subject: [PATCH] rculist: improve documentation for list_for_each_entry_from_rcu() In-Reply-To: <20180613100607.GH3593@linux.vnet.ibm.com> References: <20180613010427.GD3593@linux.vnet.ibm.com> <20180613013914.GE3593@linux.vnet.ibm.com> <87muvzihr8.fsf@notabene.neil.brown.name> <20180613100607.GH3593@linux.vnet.ibm.com> Message-ID: <874li0g1v3.fsf@notabene.neil.brown.name> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Sender: linux-nfs-owner@vger.kernel.org List-ID: --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Unfortunately the patch for adding list_for_each_entry_from_rcu() wasn't the final patch after all review. It is functionally correct but the documentation was incomplete. This patch adds this missing documentation which includes an update to the documentation for list_for_each_entry_continue_rcu() to match the documentation for the new list_for_each_entry_from_rcu(), and adds list_for_each_entry_from_rcu() and the already existing hlist_for_each_entry_from_rcu() to section 7 of whatisRCU.txt. Reviewed-by: Paul E. McKenney Signed-off-by: NeilBrown =2D-- Documentation/RCU/whatisRCU.txt | 2 ++ include/linux/rculist.h | 19 ++++++++++++++++++- 2 files changed, 20 insertions(+), 1 deletion(-) diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.= txt index 65eb856526b7..d43524493fb3 100644 =2D-- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -816,11 +816,13 @@ 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 36df6ccbc874..4786c2235b98 100644 =2D-- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -396,7 +396,16 @@ static inline void list_splice_tail_init_rcu(struct li= st_head *list, * @member: the name of the list_head within the struct. * * Continue to iterate over list of given type, continuing after =2D * the current position. + * the current 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 count) + * 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); \ @@ -411,6 +420,14 @@ static inline void list_splice_tail_init_rcu(struct li= st_head *list, * * 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 count) + * 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 positi= on + * after the given position. */ #define list_for_each_entry_from_rcu(pos, head, member) \ for (; &(pos)->member !=3D (head); \ =2D-=20 2.14.0.rc0.dirty --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAlsnM5AACgkQOeye3VZi gbmEsQ/+MSPCAMzBIMqVEHJKY0GyWBgmBMOg0Rv+BMTSM3rN67iuafzsYH1cEbsB O+c7RvtgDUdWxYfLAhNs1w+PlgmTruV48+pnfbLx1zR+O3sjir3Pm82u6VZigeNt icv+kOBWH0fLQZaRvmTvzLCy9TpwBJ937iDPW0Rl0rNlbAFPBBRTf2WnovaTKRk3 yNM6FfVj6SjGFXnfBv7JtKMLhFhL9gJ5q+kf0ygyOKZtcSkPTSa+EkSaEJ/AAaIT h50P6xrUtY1yRvvXbwKb/LqNq3XpJXkCfmAh++EUW7AreauyJokP4RHbVg92t0MG s7xMt0taFjqakJt/892c8fiw/85M3Ln4I4ztI34FDmAo2RXTeqjwtXasEQ+85FDs 8ic2GIHxXBfEgPkROwC6tfEDHSQyU5M3Kwb37XTJYnEKsIa+F4mNJQWfQkdC8JKw OtZhalvmuZvmjQsst2xyM4LiZzJvP3UApo2N9ZQu1pmCvzqW/9cfNQgFyv/+4ZtZ ngWqDEQ3yaDw9czMaGasuRyJefKxYXjLTSBjmSy0XpuXwlUQFMB8Brm3C4AvpGV0 q6P3hmbYJH1y77TCA6XaR9KR745XigNutgMSlM6K6bsQIdcZMWSPF7AKZCmtKxRO oWHK0EeZyNsiV7NybSr+9rzUlL1JNl861837LqSwAzrcqFKjgeM= =A31H -----END PGP SIGNATURE----- --=-=-=--