From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:35834 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726128AbeKRBOj (ORCPT ); Sat, 17 Nov 2018 20:14:39 -0500 Date: Sat, 17 Nov 2018 09:57:37 -0500 From: Sasha Levin To: Chenbo Feng Cc: stable@vger.kernel.org, gregkh@linuxfoundation.org, kernel-team@android.com, Daniel Colascione , Joel Fernandes , Alexei Starovoitov Subject: Re: [PATCH 4.19.y] bpf: wait for running BPF programs when updating map-in-map Message-ID: <20181117145737.GS1706@sasha-vm> References: <20181110235215.1263-1-fengc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20181110235215.1263-1-fengc@google.com> Sender: stable-owner@vger.kernel.org List-ID: On Sat, Nov 10, 2018 at 03:52:13PM -0800, Chenbo Feng wrote: >From: Daniel Colascione > >commit 1ae80cf31938c8f77c37a29bbe29e7f1cd492be8 upstream. > >The map-in-map frequently serves as a mechanism for atomic >snapshotting of state that a BPF program might record. The current >implementation is dangerous to use in this way, however, since >userspace has no way of knowing when all programs that might have >retrieved the "old" value of the map may have completed. > >This change ensures that map update operations on map-in-map map types >always wait for all references to the old map to drop before returning >to userspace. > >Signed-off-by: Daniel Colascione >Reviewed-by: Joel Fernandes (Google) >Signed-off-by: Alexei Starovoitov > >[fengc@google.com: 4.19 clean cherry-picks, no modification] >Signed-off-by: Chenbo Feng Greg has queued all 3 patches in this series to their respective trees, but I didn't see a mail from him. Thank you for the backports. -- Thanks, Sasha