diff options
Diffstat (limited to 'bsp/meta-rcar/meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0463-net-can-rcar_can-fix-possible-IRQ-storm-on-high-load.patch')
| -rw-r--r-- | bsp/meta-rcar/meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0463-net-can-rcar_can-fix-possible-IRQ-storm-on-high-load.patch | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/bsp/meta-rcar/meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0463-net-can-rcar_can-fix-possible-IRQ-storm-on-high-load.patch b/bsp/meta-rcar/meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0463-net-can-rcar_can-fix-possible-IRQ-storm-on-high-load.patch new file mode 100644 index 00000000..8fffdc42 --- /dev/null +++ b/bsp/meta-rcar/meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0463-net-can-rcar_can-fix-possible-IRQ-storm-on-high-load.patch @@ -0,0 +1,62 @@ +From f64aaea45c16fd3f34e4130b62a14389fb174b13 Mon Sep 17 00:00:00 2001 +From: Vladimir Barinov <vladimir.barinov@cogentembedded.com> +Date: Thu, 30 Jan 2020 13:17:42 +0300 +Subject: [PATCH] net: can: rcar_can: fix possible IRQ storm on high load + +We have observed rcar_canfd driver entering IRQ storm under high load, +with following scenario: +- rcar_canfd_global_interrupt() in entered due to Rx available, +- napi_schedule_prep() is called, and sets NAPIF_STATE_SCHED in state +- Rx fifo interrupts are masked, +- rcar_canfd_global_interrupt() is entered again, this time due to + error interrupt (e.g. due to overflow), +- since scheduled napi poller has not yet executed, condition for calling + napi_schedule_prep() from rcar_canfd_global_interrupt() remains true, + thus napi_schedule_prep() gets called and sets NAPIF_STATE_MISSED flag + in state, +- later, napi poller function rcar_canfd_rx_poll() gets executed, and + calls napi_complete_done(), +- due to NAPIF_STATE_MISSED flag in state, this call does not clear + NAPIF_STATE_SCHED flag from state, +- on return from napi_complete_done(), rcar_canfd_rx_poll() unmasks Rx + interrutps, +- Rx interrupt happens, rcar_canfd_global_interrupt() gets called + and calls napi_schedule_prep(), +- since NAPIF_STATE_SCHED is set in state at this time, this call + returns false, +- due to that false return, rcar_canfd_global_interrupt() returns + without masking Rx interrupt +- and this results into IRQ storm: unmasked Rx interrupt happens again + and again is misprocessed in the same way. + +This patch fixes that scenario by unmasking Rx interrupts only when +napi_complete_done() returns true, which means it has cleared +NAPIF_STATE_SCHED in state. + +Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com> +Signed-off-by: Vladimir Barinov <vladimir.barinov@cogentembedded.com> +--- + drivers/net/can/rcar/rcar_can.c | 7 ++++--- + 1 file changed, 4 insertions(+), 3 deletions(-) + +diff --git a/drivers/net/can/rcar/rcar_can.c b/drivers/net/can/rcar/rcar_can.c +index 8d2c709..b06bfc2 100644 +--- a/drivers/net/can/rcar/rcar_can.c ++++ b/drivers/net/can/rcar/rcar_can.c +@@ -705,9 +705,10 @@ static int rcar_can_rx_poll(struct napi_struct *napi, int quota) + } + /* All packets processed */ + if (num_pkts < quota) { +- napi_complete_done(napi, num_pkts); +- priv->ier |= RCAR_CAN_IER_RXFIE; +- writeb(priv->ier, &priv->regs->ier); ++ if (napi_complete_done(napi, num_pkts)) { ++ priv->ier |= RCAR_CAN_IER_RXFIE; ++ writeb(priv->ier, &priv->regs->ier); ++ } + } + return num_pkts; + } +-- +2.7.4 + |