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From:   Jesper Dangaard Brouer <jbrouer@redhat.com>
Message-ID: <1fc46094-a72a-f7e4-ef18-15edb0d56233@redhat.com>
Date:   Mon, 22 May 2023 13:08:20 +0200
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Cc:     brouer@redhat.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        Ilias Apalodimas <ilias.apalodimas@linaro.org>,
        Eric Dumazet <edumazet@google.com>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        John Fastabend <john.fastabend@gmail.com>
Subject: Re: [PATCH net] page_pool: fix inconsistency for
 page_pool_ring_[un]lock()
Content-Language: en-US
To:     Yunsheng Lin <linyunsheng@huawei.com>, davem@davemloft.net,
        kuba@kernel.org, pabeni@redhat.com
References: <20230522031714.5089-1-linyunsheng@huawei.com>
In-Reply-To: <20230522031714.5089-1-linyunsheng@huawei.com>
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Precedence: bulk


On 22/05/2023 05.17, Yunsheng Lin wrote:
> page_pool_ring_[un]lock() use in_softirq() to decide which
> spin lock variant to use, and when they are called in the
> context with in_softirq() being false, spin_lock_bh() is
> called in page_pool_ring_lock() while spin_unlock() is
> called in page_pool_ring_unlock(), because spin_lock_bh()
> has disabled the softirq in page_pool_ring_lock(), which
> causes inconsistency for spin lock pair calling.
> 
> This patch fixes it by returning in_softirq state from
> page_pool_producer_lock(), and use it to decide which
> spin lock variant to use in page_pool_producer_unlock().
> 
> As pool->ring has both producer and consumer lock, so
> rename it to page_pool_producer_[un]lock() to reflect
> the actual usage. Also move them to page_pool.c as they
> are only used there, and remove the 'inline' as the
> compiler may have better idea to do inlining or not.
> 
> Fixes: 7886244736a4 ("net: page_pool: Add bulk support for ptr_ring")
> Signed-off-by: Yunsheng Lin<linyunsheng@huawei.com>

Thanks for spotting and fixing this! :-)

Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>