bnxt_en: Fix memory corruption when FW resources change during ifdown

bnxt_en: Fix memory corruption when FW resources change during ifdown

bnxt_set_dflt_rings() assumes that it is always called before any TC has
been created.  So it doesn't take bp->num_tc into account and assumes
that it is always 0 or 1.

In the FW resource or capability change scenario, the FW will return
flags in bnxt_hwrm_if_change() that will cause the driver to
reinitialize and call bnxt_cancel_reservations().  This will lead to
bnxt_init_dflt_ring_mode() calling bnxt_set_dflt_rings() and bp->num_tc
may be greater than 1.  This will cause bp->tx_ring[] to be sized too
small and cause memory corruption in bnxt_alloc_cp_rings().

Fix it by properly scaling the TX rings by bp->num_tc in the code
paths mentioned above.  Add 2 helper functions to determine
bp->tx_nr_rings and bp->tx_nr_rings_per_tc.

Fixes: ec5d31e3c15d ("bnxt_en: Handle firmware reset status during IF_UP.")
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Signed-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Link: https://patch.msgid.link/20250825175927.459987-2-michael.chan@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>