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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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d4b890aec4
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.
Fixes:
|
||
|---|---|---|
| .. | ||
| c_can | ||
| cc770 | ||
| ifi_canfd | ||
| m_can | ||
| mscan | ||
| peak_canfd | ||
| rcar | ||
| sja1000 | ||
| softing | ||
| spi | ||
| usb | ||
| at91_can.c | ||
| dev.c | ||
| flexcan.c | ||
| grcan.c | ||
| janz-ican3.c | ||
| Kconfig | ||
| led.c | ||
| Makefile | ||
| pch_can.c | ||
| rx-offload.c | ||
| slcan.c | ||
| sun4i_can.c | ||
| ti_hecc.c | ||
| vcan.c | ||
| vxcan.c | ||
| xilinx_can.c | ||