The following trace excerpt corresponds with a NULL pointer dereference
of 'bp->irq_tbl' in bnxt_setup_inta() on an Aarch64 system after many
device resets:

    Unable to handle kernel NULL pointer dereference at ... 000000d
    ...
    pc : string+0x3c/0x80
    lr : vsnprintf+0x294/0x7e0
    sp : ffff00000f61ba70 pstate : 20000145
    x29: ffff00000f61ba70 x28: 000000000000000d
    x27: ffff0000009c8b5a x26: ffff00000f61bb80
    x25: ffff0000009c8b5a x24: 0000000000000012
    x23: 00000000ffffffe0 x22: ffff000008990428
    x21: ffff00000f61bb80 x20: 000000000000000d
    x19: 000000000000001f x18: 0000000000000000
    x17: 0000000000000000 x16: ffff800b6d0fb400
    x15: 0000000000000000 x14: ffff800b7fe31ae8
    x13: 00001ed16472c920 x12: ffff000008c6b1c9
    x11: ffff000008cf0580 x10: ffff00000f61bb80
    x9 : 00000000ffffffd8 x8 : 000000000000000c
    x7 : ffff800b684b8000 x6 : 0000000000000000
    x5 : 0000000000000065 x4 : 0000000000000001
    x3 : ffff0a00ffffff04 x2 : 000000000000001f
    x1 : 0000000000000000 x0 : 000000000000000d
    Call trace:
    string+0x3c/0x80
    vsnprintf+0x294/0x7e0
    snprintf+0x44/0x50
    __bnxt_open_nic+0x34c/0x928 [bnxt_en]
    bnxt_open+0xe8/0x238 [bnxt_en]
    __dev_open+0xbc/0x130
    __dev_change_flags+0x12c/0x168
    dev_change_flags+0x20/0x60
    ...

Ordinarily, a call to bnxt_setup_inta() (not in trace due to inlining)
would not be expected on a system supporting MSIX at all. However, if
bnxt_init_int_mode() does not end up being called after the call to
bnxt_clear_int_mode() in bnxt_fw_reset_close(), then the driver will
think that only INTA is supported and bp->irq_tbl will be NULL,
causing the above crash.

In the error recovery scenario, we call bnxt_clear_int_mode() in
bnxt_fw_reset_close() early in the sequence. Ordinarily, we will
call bnxt_init_int_mode() in bnxt_hwrm_if_change() after we
reestablish communication with the firmware after reset.  However,
if the sequence has to abort before we call bnxt_init_int_mode() and
if the user later attempts to re-open the device, then it will cause
the crash above.

We fix it in 2 ways:

1. Check for bp->irq_tbl in bnxt_setup_int_mode(). If it is NULL, call
bnxt_init_init_mode().

2. If we need to abort in bnxt_hwrm_if_change() and cannot complete
the error recovery sequence, set the BNXT_STATE_ABORT_ERR flag.  This
will cause more drastic recovery at the next attempt to re-open the
device, including a call to bnxt_init_int_mode().

Fixes: 3bc7d4a3 ("bnxt_en: Add BNXT_STATE_IN_FW_RESET state.")
Reviewed-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>