From: Jakub Kicinski <kuba@kernel.org>
To: Tony Nguyen <anthony.l.nguyen@intel.com>
Cc: davem@davemloft.net, pabeni@redhat.com, edumazet@google.com,
netdev@vger.kernel.org,
Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
magnus.karlsson@intel.com, aleksander.lobakin@intel.com,
ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org,
john.fastabend@gmail.com, bpf@vger.kernel.org,
Shannon Nelson <shannon.nelson@amd.com>,
Chandan Kumar Rout <chandanx.rout@intel.com>
Subject: Re: [PATCH net 6/8] ice: improve updating ice_{t, r}x_ring::xsk_pool
Date: Tue, 9 Jul 2024 18:45:24 -0700 [thread overview]
Message-ID: <20240709184524.232b9f57@kernel.org> (raw)
In-Reply-To: <20240708221416.625850-7-anthony.l.nguyen@intel.com>
On Mon, 8 Jul 2024 15:14:12 -0700 Tony Nguyen wrote:
> @@ -1556,7 +1556,7 @@ int ice_napi_poll(struct napi_struct *napi, int budget)
> * comparison in the irq context instead of many inside the
> * ice_clean_rx_irq function and makes the codebase cleaner.
> */
> - cleaned = rx_ring->xsk_pool ?
> + cleaned = READ_ONCE(rx_ring->xsk_pool) ?
> ice_clean_rx_irq_zc(rx_ring, budget_per_ring) :
> ice_clean_rx_irq(rx_ring, budget_per_ring);
> work_done += cleaned;
> @@ -832,8 +839,8 @@ ice_add_xsk_frag(struct ice_rx_ring *rx_ring, struct xdp_buff *first,
> */
> int ice_clean_rx_irq_zc(struct ice_rx_ring *rx_ring, int budget)
> {
> + struct xsk_buff_pool *xsk_pool = READ_ONCE(rx_ring->xsk_pool);
> unsigned int total_rx_bytes = 0, total_rx_packets = 0;
> - struct xsk_buff_pool *xsk_pool = rx_ring->xsk_pool;
> u32 ntc = rx_ring->next_to_clean;
> u32 ntu = rx_ring->next_to_use;
> struct xdp_buff *first = NULL;
This looks suspicious, you need to at least explain why it's correct.
READ_ONCE() means one access per critical section, usually.
You access it at least twice in a single NAPI pool.
next prev parent reply other threads:[~2024-07-10 1:45 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-08 22:14 [PATCH net 0/8][pull request] ice: fix AF_XDP ZC timeout and concurrency issues Tony Nguyen
2024-07-08 22:14 ` [PATCH net 1/8] ice: respect netif readiness in AF_XDP ZC related ndo's Tony Nguyen
2024-07-08 22:14 ` [PATCH net 2/8] ice: don't busy wait for Rx queue disable in ice_qp_dis() Tony Nguyen
2024-07-08 22:14 ` [PATCH net 3/8] ice: replace synchronize_rcu with synchronize_net Tony Nguyen
2024-07-08 22:14 ` [PATCH net 4/8] ice: modify error handling when setting XSK pool in ndo_bpf Tony Nguyen
2024-07-08 22:14 ` [PATCH net 5/8] ice: toggle netif_carrier when setting up XSK pool Tony Nguyen
2024-07-08 22:14 ` [PATCH net 6/8] ice: improve updating ice_{t, r}x_ring::xsk_pool Tony Nguyen
2024-07-10 1:45 ` Jakub Kicinski [this message]
2024-07-23 23:46 ` Maciej Fijalkowski
2024-07-24 14:57 ` Jakub Kicinski
2024-07-24 15:49 ` Maciej Fijalkowski
2024-07-25 13:38 ` Jakub Kicinski
2024-07-25 18:31 ` Maciej Fijalkowski
2024-07-25 23:07 ` Jakub Kicinski
2024-07-26 13:43 ` Maciej Fijalkowski
2024-07-26 14:37 ` Jakub Kicinski
2024-07-08 22:14 ` [PATCH net 7/8] ice: add missing WRITE_ONCE when clearing ice_rx_ring::xdp_prog Tony Nguyen
2024-07-08 22:14 ` [PATCH net 8/8] ice: xsk: fix txq interrupt mapping Tony Nguyen
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