From: Sasha Levin <sashal@kernel.org>
To: Chenbo Feng <fengc@google.com>
Cc: stable@vger.kernel.org, gregkh@linuxfoundation.org,
kernel-team@android.com, Daniel Colascione <dancol@google.com>,
Joel Fernandes <joel@joelfernandes.org>,
Alexei Starovoitov <ast@kernel.org>
Subject: Re: [PATCH 4.19.y] bpf: wait for running BPF programs when updating map-in-map
Date: Sat, 17 Nov 2018 09:57:37 -0500 [thread overview]
Message-ID: <20181117145737.GS1706@sasha-vm> (raw)
In-Reply-To: <20181110235215.1263-1-fengc@google.com>
On Sat, Nov 10, 2018 at 03:52:13PM -0800, Chenbo Feng wrote:
>From: Daniel Colascione <dancol@google.com>
>
>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 <dancol@google.com>
>Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
>Signed-off-by: Alexei Starovoitov <ast@kernel.org>
>
>[fengc@google.com: 4.19 clean cherry-picks, no modification]
>Signed-off-by: Chenbo Feng <fengc@google.com>
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
prev parent reply other threads:[~2018-11-18 1:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-10 23:52 [PATCH 4.19.y] bpf: wait for running BPF programs when updating map-in-map Chenbo Feng
2018-11-10 23:52 ` [PATCH 4.4.y] ext4: avoid running out of journal credits when appending to an inline file Chenbo Feng
2018-11-10 23:52 ` [PATCH 4.14.y] bpf: wait for running BPF programs when updating map-in-map Chenbo Feng
2018-11-17 14:57 ` Sasha Levin [this message]
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