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[2a03:2880:ff:d::face:b00c]) by smtp.gmail.com with ESMTPSA id l5-20020a170903120500b001d349fcb70dsm12563264plh.202.2023.12.19.13.04.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Dec 2023 13:04:19 -0800 (PST) From: David Wei To: io-uring@vger.kernel.org, netdev@vger.kernel.org Cc: Jens Axboe , Pavel Begunkov , Jakub Kicinski , Paolo Abeni , "David S. Miller" , Eric Dumazet , Jesper Dangaard Brouer , David Ahern , Mina Almasry Subject: [RFC PATCH v3 16/20] net: execute custom callback from napi Date: Tue, 19 Dec 2023 13:03:53 -0800 Message-Id: <20231219210357.4029713-17-dw@davidwei.uk> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20231219210357.4029713-1-dw@davidwei.uk> References: <20231219210357.4029713-1-dw@davidwei.uk> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Pavel Begunkov Sometimes we want to access a napi protected resource from task context like in the case of io_uring zc falling back to copy and accessing the buffer ring. Add a helper function that allows to execute a custom function from napi context by first stopping it similarly to napi_busy_loop(). Experimental, needs much polishing and sharing bits with napi_busy_loop(). Signed-off-by: Pavel Begunkov Signed-off-by: David Wei --- include/net/busy_poll.h | 7 +++++++ net/core/dev.c | 46 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 53 insertions(+) diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h index 4dabeb6c76d3..64238467e00a 100644 --- a/include/net/busy_poll.h +++ b/include/net/busy_poll.h @@ -47,6 +47,8 @@ bool sk_busy_loop_end(void *p, unsigned long start_time); void napi_busy_loop(unsigned int napi_id, bool (*loop_end)(void *, unsigned long), void *loop_end_arg, bool prefer_busy_poll, u16 budget); +void napi_execute(struct napi_struct *napi, + void (*cb)(void *), void *cb_arg); #else /* CONFIG_NET_RX_BUSY_POLL */ static inline unsigned long net_busy_loop_on(void) @@ -59,6 +61,11 @@ static inline bool sk_can_busy_loop(struct sock *sk) return false; } +static inline void napi_execute(struct napi_struct *napi, + void (*cb)(void *), void *cb_arg) +{ +} + #endif /* CONFIG_NET_RX_BUSY_POLL */ static inline unsigned long busy_loop_current_time(void) diff --git a/net/core/dev.c b/net/core/dev.c index e55750c47245..2dd4f3846535 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6537,6 +6537,52 @@ void napi_busy_loop(unsigned int napi_id, } EXPORT_SYMBOL(napi_busy_loop); +void napi_execute(struct napi_struct *napi, + void (*cb)(void *), void *cb_arg) +{ + bool done = false; + unsigned long val; + void *have_poll_lock = NULL; + + rcu_read_lock(); + + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + preempt_disable(); + for (;;) { + local_bh_disable(); + val = READ_ONCE(napi->state); + + /* If multiple threads are competing for this napi, + * we avoid dirtying napi->state as much as we can. + */ + if (val & (NAPIF_STATE_DISABLE | NAPIF_STATE_SCHED | + NAPIF_STATE_IN_BUSY_POLL)) + goto restart; + + if (cmpxchg(&napi->state, val, + val | NAPIF_STATE_IN_BUSY_POLL | + NAPIF_STATE_SCHED) != val) + goto restart; + + have_poll_lock = netpoll_poll_lock(napi); + cb(cb_arg); + done = true; + gro_normal_list(napi); + local_bh_enable(); + break; +restart: + local_bh_enable(); + if (unlikely(need_resched())) + break; + cpu_relax(); + } + if (done) + busy_poll_stop(napi, have_poll_lock, false, 1); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + preempt_enable(); + rcu_read_unlock(); +} + #endif /* CONFIG_NET_RX_BUSY_POLL */ static void napi_hash_add(struct napi_struct *napi) -- 2.39.3