From: Nikita Yushchenko <nikita.yoush@xxxxxxxxxxxxxxxxxx>
commit d4b890aec4bea7334ca2ca56fd3b12fb48a00cd1 upstream.
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: dd3bd23eb438 ("can: rcar_canfd: Add Renesas R-Car CAN FD driver")
Signed-off-by: Nikita Yushchenko <nikita.yoush@xxxxxxxxxxxxxxxxxx>
Cc: linux-stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/can/rcar/rcar_canfd.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
--- a/drivers/net/can/rcar/rcar_canfd.c
+++ b/drivers/net/can/rcar/rcar_canfd.c
@@ -1508,10 +1508,11 @@ static int rcar_canfd_rx_poll(struct nap
/* All packets processed */
if (num_pkts < quota) {
- napi_complete_done(napi, num_pkts);
- /* Enable Rx FIFO interrupts */
- rcar_canfd_set_bit(priv->base, RCANFD_RFCC(ridx),
- RCANFD_RFCC_RFIE);
+ if (napi_complete_done(napi, num_pkts)) {
+ /* Enable Rx FIFO interrupts */
+ rcar_canfd_set_bit(priv->base, RCANFD_RFCC(ridx),
+ RCANFD_RFCC_RFIE);
+ }
}
return num_pkts;
}
