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([2a01:4b00:bd21:4f00:7cc6:d3ca:494:116c]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-429bca06fa5sm362612f8f.14.2025.10.30.08.24.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Oct 2025 08:24:35 -0700 (PDT) Message-ID: Date: Thu, 30 Oct 2025 15:24:33 +0000 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 7/8] io_uring/zcrx: add refcount to ifq and remove ifq->ctx From: Pavel Begunkov To: David Wei , io-uring@vger.kernel.org, netdev@vger.kernel.org Cc: Jens Axboe References: <20251028174639.1244592-1-dw@davidwei.uk> <20251028174639.1244592-8-dw@davidwei.uk> <810d45da-7d60-460a-a250-eacf07f3d005@gmail.com> <9fe0088d-f592-47c4-8b95-7c85a494cf70@gmail.com> Content-Language: en-US In-Reply-To: <9fe0088d-f592-47c4-8b95-7c85a494cf70@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 10/29/25 16:16, Pavel Begunkov wrote: > On 10/29/25 15:22, Pavel Begunkov wrote: >> On 10/28/25 17:46, David Wei wrote: ...>>>   void io_unregister_zcrx_ifqs(struct io_ring_ctx *ctx) >>>   { >>>       struct io_zcrx_ifq *ifq; >>> @@ -743,7 +730,10 @@ void io_unregister_zcrx_ifqs(struct io_ring_ctx *ctx) >>>           } >>>           if (!ifq) >>>               break; >>> -        io_zcrx_ifq_free(ifq); >>> +        if (refcount_dec_and_test(&ifq->refs)) { >>> +            io_zcrx_scrub(ifq); >>> +            io_zcrx_ifq_free(ifq); >>> +        } >>>       } >>>       xa_destroy(&ctx->zcrx_ctxs); >>> @@ -894,15 +884,11 @@ static int io_pp_zc_init(struct page_pool *pp) >>>       if (ret) >>>           return ret; >>> -    percpu_ref_get(&ifq->ctx->refs); >>>       return 0; >> >> refcount_inc(); > > Which would add another ref cycle problem, the same that IIRC > was solved with two step shutdown + release. I'll take a closer > look. The simplest solution is to keep the two 2 level release and split refcounting for sharing. It's still better as now shutdown can be folded into the io_uring ifq unregstration helper. https://github.com/isilence/linux.git zcrx/zcrx-sharing https://github.com/isilence/liburing.git zcrx/zcrx-sharing I fixed up synchronisation and drafted the export/import via a file part, take a look. -- Pavel Begunkov