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This commit fixes the potential deadlock caused by the console Rx
and Tx processing at the same time. Rx and Tx both take the console
and tmfifo spinlock but in different order which causes potential
deadlock. The fix is to use different tmfifo spinlock for Rx and
Tx since they protect different resources and it's safe to split
the lock.
Below is the reported call trace when copying/pasting large string
in the console.
Rx:
_raw_spin_lock_irqsave (hvc lock)
__hvc_poll
hvc_poll
in_intr
vring_interrupt
mlxbf_tmfifo_rxtx_one_desc (tmfifo lock)
mlxbf_tmfifo_rxtx
mlxbf_tmfifo_work_rxtx
Tx:
_raw_spin_lock_irqsave (tmfifo lock)
mlxbf_tmfifo_virtio_notify
virtqueue_notify
virtqueue_kick
put_chars
hvc_push
hvc_write (hvc lock)
...
do_tty_write
tty_write
Fixes: 1357dfd7261f ("platform/mellanox: Add TmFifo driver for Mellanox BlueField Soc")
Cc: <stable@vger.kernel.org> # 5.4+
Reviewed-by: David Woods <dwoods@mellanox.com>
Signed-off-by: Liming Sun <lsun@mellanox.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
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