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Date: Thu, 22 Jan 2015 16:50:37 +0300 From: Sergei Shtylyov <sergei.shtylyov@...entembedded.com> To: Ben Hutchings <ben.hutchings@...ethink.co.uk>, "David S.Miller" <davem@...emloft.net> CC: netdev@...r.kernel.org, linux-kernel@...ts.codethink.co.uk, Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@...esas.com>, Mitsuhiro Kimura <mitsuhiro.kimura.kc@...esas.com>, Hisashi Nakamura <hisashi.nakamura.ak@...esas.com>, Yoshihiro Kaneko <ykaneko0929@...il.com> Subject: Re: [PATCH net 4/4] sh_eth: Fix serialisation of interrupt disable with interrupt & NAPI handlers Hello. On 1/22/2015 3:44 PM, Ben Hutchings wrote: > In order to stop the RX path accessing the RX ring while it's being > stopped or resized, we clear the interrupt mask (EESIPR) and then call > free_irq() or synchronise_irq(). This is insufficient because the > interrupt handler or NAPI poller may set EESIPR again after we clear > it. Hm, how come the interrupt handler gets called when we have disabled all interrupts? Is it unmaskable EESR.ECI interrupt? BTW, I'm not seeing where the interrupt handler enables interrupts again; only NAPI poller does that AFAIK. > Also, in sh_eth_set_ringparam() we currently don't disable NAPI > polling at all. > I could easily trigger a crash by running the loop: > while ethtool -G eth0 rx 128 && ethtool -G eth0 rx 64; do echo -n .; done Oh, never done any 'ethtool' tests... > and 'ping -f' toward the sh_eth port from another machine. To fix this: > - Add a software flag (irq_enabled) to signal whether interrupts > should be enabled > - In the interrupt handler, if the flag is clear then clear EESIPR > and return > - In the NAPI poller, if the flag is clear then don't set EESIPR > - Set the flag before enabling interrupts in sh_eth_dev_init() and > sh_eth_set_ringparam() > - Clear the flag and serialise with the interrupt and NAPI > handlers before clearing EESIPR in sh_eth_close() and > sh_eth_set_ringparam() > After this, I could run the loop for 100,000 iterations successfully. > Signed-off-by: Ben Hutchings <ben.hutchings@...ethink.co.uk> [...] > diff --git a/drivers/net/ethernet/renesas/sh_eth.h b/drivers/net/ethernet/renesas/sh_eth.h > index 7bfaf1c..259d03f 100644 > --- a/drivers/net/ethernet/renesas/sh_eth.h > +++ b/drivers/net/ethernet/renesas/sh_eth.h > @@ -513,6 +513,7 @@ struct sh_eth_private { > u32 rx_buf_sz; /* Based on MTU+slack. */ > int edmac_endian; > struct napi_struct napi; > + bool irq_enabled; > /* MII transceiver section. */ > u32 phy_id; /* PHY ID */ > struct mii_bus *mii_bus; /* MDIO bus control */ In order to conserve space, I'd have added that field after 'vlan_num_ids', just before the 1-bit fields... WBR, Sergei -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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