From: "Björn Töpel" <bjorn.topel@intel.com>
To: "Jakub Kicinski" <jakub.kicinski@netronome.com>,
"Björn Töpel" <bjorn.topel@gmail.com>
Cc: netdev@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
bpf@vger.kernel.org, davem@davemloft.net, hawk@kernel.org,
john.fastabend@gmail.com, magnus.karlsson@intel.com,
jonathan.lemon@gmail.com
Subject: Re: [PATCH bpf-next 2/8] xdp: simplify cpumap cleanup
Date: Wed, 18 Dec 2019 18:48:28 +0100 [thread overview]
Message-ID: <77fabe3b-2314-8826-a5a3-3a530f41eb0c@intel.com> (raw)
In-Reply-To: <20191218094723.13ab0d54@cakuba.netronome.com>
On 2019-12-18 18:47, Jakub Kicinski wrote:
> On Wed, 18 Dec 2019 11:53:54 +0100, Björn Töpel wrote:
>> From: Björn Töpel <bjorn.topel@intel.com>
>>
>> After the RCU flavor consolidation [1], call_rcu() and
>> synchronize_rcu() waits for preempt-disable regions (NAPI) in addition
>> to the read-side critical sections. As a result of this, the cleanup
>> code in cpumap can be simplified
>>
>> * There is no longer a need to flush in __cpu_map_entry_free, since we
>> know that this has been done when the call_rcu() callback is
>> triggered.
>>
>> * When freeing the map, there is no need to explicitly wait for a
>> flush. It's guaranteed to be done after the synchronize_rcu() call
>> in cpu_map_free().
>>
>> [1] https://lwn.net/Articles/777036/
>>
>> Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
>
> Probably transient but:
>
> ../kernel/bpf/cpumap.c: In function "cpu_map_free":
> ../kernel/bpf/cpumap.c:502:6: warning: unused variable "cpu" [-Wunused-variable]
> 502 | int cpu;
> | ^~~
>
> I think there are also warnings in patch 4.
>
Ugh. Thanks, I'll respin!
Björn
next prev parent reply other threads:[~2019-12-18 17:48 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 10:53 [PATCH bpf-next 0/8] Simplify xdp_do_redirect_map()/xdp_do_flush_map() and XDP maps Björn Töpel
2019-12-18 10:53 ` [PATCH bpf-next 1/8] xdp: simplify devmap cleanup Björn Töpel
2019-12-18 11:14 ` Toke Høiland-Jørgensen
2019-12-18 10:53 ` [PATCH bpf-next 2/8] xdp: simplify cpumap cleanup Björn Töpel
2019-12-18 11:15 ` Toke Høiland-Jørgensen
2019-12-18 17:47 ` Jakub Kicinski
2019-12-18 17:48 ` Björn Töpel [this message]
2019-12-18 10:53 ` [PATCH bpf-next 3/8] xdp: fix graze->grace type-o in cpumap comments Björn Töpel
2019-12-18 11:18 ` Toke Høiland-Jørgensen
2019-12-18 10:53 ` [PATCH bpf-next 4/8] xsk: make xskmap flush_list common for all map instances Björn Töpel
2019-12-18 11:19 ` Toke Høiland-Jørgensen
2019-12-18 10:53 ` [PATCH bpf-next 5/8] xdp: make devmap " Björn Töpel
2019-12-18 11:19 ` Toke Høiland-Jørgensen
2019-12-18 10:53 ` [PATCH bpf-next 6/8] xdp: make cpumap " Björn Töpel
2019-12-18 11:19 ` Toke Høiland-Jørgensen
2019-12-18 10:53 ` [PATCH bpf-next 7/8] xdp: remove map_to_flush and map swap detection Björn Töpel
2019-12-18 11:20 ` Toke Høiland-Jørgensen
2019-12-18 13:03 ` Jesper Dangaard Brouer
2019-12-18 13:09 ` Björn Töpel
2019-12-18 10:54 ` [PATCH bpf-next 8/8] xdp: simplify __bpf_tx_xdp_map() Björn Töpel
2019-12-18 11:20 ` Toke Høiland-Jørgensen
2019-12-18 11:11 ` [PATCH bpf-next 0/8] Simplify xdp_do_redirect_map()/xdp_do_flush_map() and XDP maps Jesper Dangaard Brouer
2019-12-18 11:39 ` Björn Töpel
2019-12-18 12:03 ` Jesper Dangaard Brouer
2019-12-18 12:18 ` Björn Töpel
2019-12-18 12:32 ` Björn Töpel
2019-12-18 12:40 ` Jesper Dangaard Brouer
2019-12-18 12:48 ` Björn Töpel
2019-12-19 0:39 ` Andrii Nakryiko
2019-12-19 19:33 ` Jesper Dangaard Brouer
2019-12-19 20:08 ` Daniel Borkmann
2019-12-19 22:56 ` Andrii Nakryiko
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