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Message-ID: <20240909180013.4e064fd5@kernel.org> Date: Mon, 9 Sep 2024 18:00:13 -0700 From: Jakub Kicinski <kuba@...nel.org> To: Sean Anderson <sean.anderson@...ux.dev> Cc: Radhey Shyam Pandey <radhey.shyam.pandey@....com>, "David S . Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org, Michal Simek <michal.simek@....com>, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, Andy Chiu <andy.chiu@...ive.com>, Daniel Borkmann <daniel@...earbox.net> Subject: Re: [PATCH net v2] net: xilinx: axienet: Fix packet counting On Fri, 6 Sep 2024 12:42:27 -0400 Sean Anderson wrote: > axienet_free_tx_chain returns the number of DMA descriptors it's > handled. However, axienet_tx_poll treats the return as the number of > packets. When scatter-gather SKBs are enabled, a single packet may use > multiple DMA descriptors, which causes incorrect packet counts. Fix this > by explicitly keepting track of the number of packets processed as > separate from the DMA descriptors. > > Fixes: 8a3b7a252dca ("drivers/net/ethernet/xilinx: added Xilinx AXI Ethernet driver") > Signed-off-by: Sean Anderson <sean.anderson@...ux.dev> > diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c > index 9aeb7b9f3ae4..556033849d55 100644 > --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c > +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c > @@ -670,21 +670,21 @@ static int axienet_device_reset(struct net_device *ndev) > * @force: Whether to clean descriptors even if not complete > * @sizep: Pointer to a u32 filled with the total sum of all bytes > * in all cleaned-up descriptors. Ignored if NULL. > - * @budget: NAPI budget (use 0 when not called from NAPI poll) > + * @budget: NAPI budget (use INT_MAX when not called from NAPI poll) use INT_MAX and force=true when ... ? To make sure the dependency is clear. But actually... > * > * Would either be called after a successful transmit operation, or after > * there was an error when setting up the chain. > - * Returns the number of descriptors handled. > + * Returns the number of packets handled. > */ > static int axienet_free_tx_chain(struct axienet_local *lp, u32 first_bd, > int nr_bds, bool force, u32 *sizep, int budget) > { > struct axidma_bd *cur_p; > unsigned int status; > + int i, packets = 0; > dma_addr_t phys; > - int i; > > - for (i = 0; i < nr_bds; i++) { > + for (i = 0; i < nr_bds && packets < budget; i++) { why are you doing this? To make sure drivers doesn't complete more than "budget" Tx skbs? The budget is really for Rx, for Tx you can use a reasonable fixed value, independent of what budget core passes in, e.g. 128. See: https://www.kernel.org/doc/html/next/networking/napi.html#datapath-api > cur_p = &lp->tx_bd_v[(first_bd + i) % lp->tx_bd_num]; > status = cur_p->status; > > @@ -701,8 +701,10 @@ static int axienet_free_tx_chain(struct axienet_local *lp, u32 first_bd, > (cur_p->cntrl & XAXIDMA_BD_CTRL_LENGTH_MASK), > DMA_TO_DEVICE); > > - if (cur_p->skb && (status & XAXIDMA_BD_STS_COMPLETE_MASK)) > - napi_consume_skb(cur_p->skb, budget); > + if (cur_p->skb && (status & XAXIDMA_BD_STS_COMPLETE_MASK)) { > + napi_consume_skb(cur_p->skb, force ? 0 : budget); > + packets++; > + } > > cur_p->app0 = 0; > cur_p->app1 = 0; > @@ -718,7 +720,13 @@ static int axienet_free_tx_chain(struct axienet_local *lp, u32 first_bd, > *sizep += status & XAXIDMA_BD_STS_ACTUAL_LEN_MASK; > } > > - return i; > + if (!force) { > + lp->tx_bd_ci += i; > + if (lp->tx_bd_ci >= lp->tx_bd_num) > + lp->tx_bd_ci %= lp->tx_bd_num; > + } Moving this chunk into axienet_free_tx_chain() is a noop, right? Please avoid code cleanups in fixes. > + return packets; > } > > /** -- pw-bot: cr
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