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From: David Miller <davem@davemloft.net>
To: john.fastabend@gmail.com
Cc: ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org,
	davejwatson@fb.com
Subject: Re: [bpf-next PATCH 02/16] sockmap: convert refcnt to an atomic refcnt
Date: Mon, 05 Mar 2018 16:34:28 -0500 (EST)	[thread overview]
Message-ID: <20180305.163428.1811826895016433265.davem@davemloft.net> (raw)
In-Reply-To: <20180305195106.6612.55622.stgit@john-Precision-Tower-5810>

From: John Fastabend <john.fastabend@gmail.com>
Date: Mon, 05 Mar 2018 11:51:06 -0800

> The sockmap refcnt up until now has been wrapped in the
> sk_callback_lock(). So its not actually needed any locking of its
> own. The counter itself tracks the lifetime of the psock object.
> Sockets in a sockmap have a lifetime that is independent of the
> map they are part of. This is possible because a single socket may
> be in multiple maps. When this happens we can only release the
> psock data associated with the socket when the refcnt reaches
> zero. There are three possible delete sock reference decrement
> paths first through the normal sockmap process, the user deletes
> the socket from the map. Second the map is removed and all sockets
> in the map are removed, delete path is similar to case 1. The third
> case is an asyncronous socket event such as a closing the socket. The
> last case handles removing sockets that are no longer available.
> For completeness, although inc does not pose any problems in this
> patch series, the inc case only happens when a psock is added to a
> map.
> 
> Next we plan to add another socket prog type to handle policy and
> monitoring on the TX path. When we do this however we will need to
> keep a reference count open across the sendmsg/sendpage call and
> holding the sk_callback_lock() here (on every send) seems less than
> ideal, also it may sleep in cases where we hit memory pressure.
> Instead of dealing with these issues in some clever way simply make
> the reference counting a refcnt_t type and do proper atomic ops.
> 
> Signed-off-by: John Fastabend <john.fastabend@gmail.com>

Acked-by: David S. Miller <davem@davemloft.net>

  reply	other threads:[~2018-03-05 21:34 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-05 19:50 [bpf-next PATCH 00/16] bpf,sockmap: sendmsg/sendfile ULP John Fastabend
2018-03-05 19:51 ` [bpf-next PATCH 01/16] sock: make static tls function alloc_sg generic sock helper John Fastabend
2018-03-05 21:32   ` David Miller
2018-03-05 19:51 ` [bpf-next PATCH 02/16] sockmap: convert refcnt to an atomic refcnt John Fastabend
2018-03-05 21:34   ` David Miller [this message]
2018-03-05 19:51 ` [bpf-next PATCH 03/16] net: do_tcp_sendpages flag to avoid SKBTX_SHARED_FRAG John Fastabend
2018-03-05 19:51 ` [bpf-next PATCH 04/16] net: generalize sk_alloc_sg to work with scatterlist rings John Fastabend
2018-03-05 21:35   ` David Miller
2018-03-05 19:51 ` [bpf-next PATCH 05/16] bpf: create tcp_bpf_ulp allowing BPF to monitor socket TX/RX data John Fastabend
2018-03-05 21:40   ` David Miller
2018-03-05 22:53     ` John Fastabend
2018-03-06  5:42       ` David Miller
2018-03-06  6:22         ` John Fastabend
2018-03-06  6:42           ` David Miller
2018-03-06  7:06             ` John Fastabend
2018-03-06 15:47               ` David Miller
2018-03-06 18:18                 ` John Fastabend
2018-03-07  3:25                   ` John Fastabend
2018-03-07  4:41                     ` David Miller
2018-03-07 13:03                     ` Daniel Borkmann
2018-03-05 19:51 ` [bpf-next PATCH 06/16] bpf: sockmap, add bpf_msg_apply_bytes() helper John Fastabend
2018-03-05 19:51 ` [bpf-next PATCH 07/16] bpf: sockmap, add msg_cork_bytes() helper John Fastabend
2018-03-05 19:51 ` [bpf-next PATCH 08/16] bpf: add map tests for BPF_PROG_TYPE_SK_MSG John Fastabend
2018-03-05 19:51 ` [bpf-next PATCH 09/16] bpf: add verifier " John Fastabend
2018-03-05 19:51 ` [bpf-next PATCH 10/16] bpf: sockmap sample, add option to attach SK_MSG program John Fastabend
2018-03-05 19:51 ` [bpf-next PATCH 11/16] bpf: sockmap sample, add sendfile test John Fastabend
2018-03-05 19:51 ` [bpf-next PATCH 12/16] bpf: sockmap sample, add data verification option John Fastabend
2018-03-05 19:52 ` [bpf-next PATCH 13/16] bpf: sockmap, add sample option to test apply_bytes helper John Fastabend
2018-03-05 19:52 ` [bpf-next PATCH 14/16] bpf: sockmap sample support for bpf_msg_cork_bytes() John Fastabend
2018-03-05 19:52 ` [bpf-next PATCH 15/16] sockmap: add SK_DROP tests John Fastabend
2018-03-05 19:52 ` [bpf-next PATCH 16/16] bpf: sockmap test script John Fastabend

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