Re: [PATCH mptcp-net 0/2] mptcp: "fix suspicious RCU usage" warnings

[Matthieu Baerts <matttbe@kernel.org>]

Hi Paolo,

On 17/10/2024 11:38, Paolo Abeni wrote:
> On 10/16/24 21:05, Matthieu Baerts (NGI0) wrote:
>> Enabling PROVE_RCU_LIST (and RCU_EXPERT) shows list_for_each_entry_rcu()
>> from mptcp_sched_find() not being used with RCU read lock held.
>>
>> The first patch is a fix for -net. The other one is for a commit that is
>> only in our tree.
>>
>> Link: https://lore.kernel.org/20241016011144.3058445-1-kuba@kernel.org
>> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
>> ---
>> Matthieu Baerts (NGI0) (2):
>>        mptcp: init: protect sched with rcu_read_lock
>>        Squash to "bpf: Add bpf_mptcp_sched_ops"
>>
>>   net/mptcp/bpf.c      | 10 +++++++---
>>   net/mptcp/protocol.c |  2 ++
>>   2 files changed, 9 insertions(+), 3 deletions(-)
>> ---
>> base-commit: baccd7675477b1db387aa71b48c3312b5fb67a5d
>> change-id: 20241016-mptcp-sched-find-rcu-649ce3399334
>>
>> Best regards,
> 
> Only slightly related, but mptcp_get_available_schedulers() currently
> acquires both the rcu and the sched_list lock. I think the latter is not
> needed and should be dropped.

Good point, the list is not modified.
I can send a patch for that.

(sorry, I should not have applied these patches that quickly, I was busy
adding 'debug' support for the BPF tests in our CI, and I didn't think
it was too quick)

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.