git.ipfire.org Git - thirdparty/kernel/stable-queue.git/blob

   1 From 702de2c21eed04c67cefaaedc248ef16e5f6b293 Mon Sep 17 00:00:00 2001
   2 From: Biju Das <biju.das.jz@bp.renesas.com>
   3 Date: Tue, 25 Oct 2022 16:56:55 +0100
   4 Subject: can: rcar_canfd: rcar_canfd_handle_global_receive(): fix IRQ storm on global FIFO receive
   5
   6 From: Biju Das <biju.das.jz@bp.renesas.com>
   7
   8 commit 702de2c21eed04c67cefaaedc248ef16e5f6b293 upstream.
   9
  10 We are seeing an IRQ storm on the global receive IRQ line under heavy
  11 CAN bus load conditions with both CAN channels enabled.
  12
  13 Conditions:
  14
  15 The global receive IRQ line is shared between can0 and can1, either of
  16 the channels can trigger interrupt while the other channel's IRQ line
  17 is disabled (RFIE).
  18
  19 When global a receive IRQ interrupt occurs, we mask the interrupt in
  20 the IRQ handler. Clearing and unmasking of the interrupt is happening
  21 in rx_poll(). There is a race condition where rx_poll() unmasks the
  22 interrupt, but the next IRQ handler does not mask the IRQ due to
  23 NAPIF_STATE_MISSED flag (e.g.: can0 RX FIFO interrupt is disabled and
  24 can1 is triggering RX interrupt, the delay in rx_poll() processing
  25 results in setting NAPIF_STATE_MISSED flag) leading to an IRQ storm.
  26
  27 This patch fixes the issue by checking IRQ active and enabled before
  28 handling the IRQ on a particular channel.
  29
  30 Fixes: dd3bd23eb438 ("can: rcar_canfd: Add Renesas R-Car CAN FD driver")
  31 Suggested-by: Marc Kleine-Budde <mkl@pengutronix.de>
  32 Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
  33 Link: https://lore.kernel.org/all/20221025155657.1426948-2-biju.das.jz@bp.renesas.com
  34 Cc: stable@vger.kernel.org
  35 [mkl: adjust commit message]
  36 Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
  37 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  38 ---
  39  drivers/net/can/rcar/rcar_canfd.c |    6 ++++--
  40  1 file changed, 4 insertions(+), 2 deletions(-)
  41
  42 --- a/drivers/net/can/rcar/rcar_canfd.c
  43 +++ b/drivers/net/can/rcar/rcar_canfd.c
  44 @@ -1157,11 +1157,13 @@ static void rcar_canfd_handle_global_rec
  45  {
  46         struct rcar_canfd_channel *priv = gpriv->ch[ch];
  47         u32 ridx = ch + RCANFD_RFFIFO_IDX;
  48 -       u32 sts;
  49 +       u32 sts, cc;
  50
  51         /* Handle Rx interrupts */
  52         sts = rcar_canfd_read(priv->base, RCANFD_RFSTS(gpriv, ridx));
  53 -       if (likely(sts & RCANFD_RFSTS_RFIF)) {
  54 +       cc = rcar_canfd_read(priv->base, RCANFD_RFCC(gpriv, ridx));
  55 +       if (likely(sts & RCANFD_RFSTS_RFIF &&
  56 +                  cc & RCANFD_RFCC_RFIE)) {
  57                 if (napi_schedule_prep(&priv->napi)) {
  58                         /* Disable Rx FIFO interrupts */
  59                         rcar_canfd_clear_bit(priv->base,