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| author | Nikita Yushchenko <nikita.yoush@cogentembedded.com> | 2019-06-26 16:08:48 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-08-16 10:13:50 +0200 |
| commit | 709982a1422ce8d70f2d1967490bbf8f58c6577e (patch) | |
| tree | 9342cd54b7007fd16c8c2e339d2b5b8667b0e10e /drivers/net/can | |
| parent | f0d684599b4f2525a6a7fe0cde8dff6800d16a22 (diff) | |
| download | linux-stable-709982a1422ce8d70f2d1967490bbf8f58c6577e.tar.gz linux-stable-709982a1422ce8d70f2d1967490bbf8f58c6577e.tar.bz2 linux-stable-709982a1422ce8d70f2d1967490bbf8f58c6577e.zip | |
can: rcar_canfd: fix possible IRQ storm on high load
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@cogentembedded.com>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/net/can')
| -rw-r--r-- | drivers/net/can/rcar/rcar_canfd.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c index 602c19e23f05..786d852a70d5 100644 --- a/drivers/net/can/rcar/rcar_canfd.c +++ b/drivers/net/can/rcar/rcar_canfd.c @@ -1512,10 +1512,11 @@ static int rcar_canfd_rx_poll(struct napi_struct *napi, int quota) /* 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; } |