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   1 From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
   2 Date: Mon, 18 Nov 2019 11:52:41 +0100
   3 Subject: [PATCH FIX] brcmfmac: disable PCIe interrupts before bus reset
   4 MIME-Version: 1.0
   5 Content-Type: text/plain; charset=UTF-8
   6 Content-Transfer-Encoding: 8bit
   7
   8 Keeping interrupts on could result in brcmfmac freeing some resources
   9 and then IRQ handlers trying to use them. That was obviously a straight
  10 path for crashing a kernel.
  11
  12 Example:
  13 CPU0                           CPU1
  14 ----                           ----
  15 brcmf_pcie_reset
  16   brcmf_pcie_bus_console_read
  17   brcmf_detach
  18     ...
  19     brcmf_fweh_detach
  20     brcmf_proto_detach
  21                                brcmf_pcie_isr_thread
  22                                  ...
  23                                  brcmf_proto_msgbuf_rx_trigger
  24                                    ...
  25                                    drvr->proto->pd
  26     brcmf_pcie_release_irq
  27
  28 [  363.789218] Unable to handle kernel NULL pointer dereference at virtual address 00000038
  29 [  363.797339] pgd = c0004000
  30 [  363.800050] [00000038] *pgd=00000000
  31 [  363.803635] Internal error: Oops: 17 [#1] SMP ARM
  32 (...)
  33 [  364.029209] Backtrace:
  34 [  364.031725] [<bf243838>] (brcmf_proto_msgbuf_rx_trigger [brcmfmac]) from [<bf2471dc>] (brcmf_pcie_isr_thread+0x228/0x274 [brcmfmac])
  35 [  364.043662]  r7:00000001 r6:c8ca0000 r5:00010000 r4:c7b4f800
  36
  37 Fixes: 4684997d9eea ("brcmfmac: reset PCIe bus on a firmware crash")
  38 Cc: stable@vger.kernel.org # v5.2+
  39 Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
  40 ---
  41  drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c | 2 ++
  42  1 file changed, 2 insertions(+)
  43
  44 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c
  45 +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c
  46 @@ -1427,6 +1427,8 @@ static int brcmf_pcie_reset(struct devic
  47         struct brcmf_fw_request *fwreq;
  48         int err;
  49
  50 +       brcmf_pcie_intr_disable(devinfo);
  51 +
  52         brcmf_pcie_bus_console_read(devinfo, true);
  53
  54         brcmf_detach(dev);