Re: [PATCH v6 2/5] serial: serialize asynchronous write wakeups with the port lock

[sashiko-bot@kernel.org]

> uart_write_wakeup() expects the UART port lock to be held. Several worker,
> DMA completion and interrupt paths call it without that lock, including
> indirect calls from uart_handle_cts_change() and the transmit helpers.
> 
> Take the port lock around these notifications or their transmit helper.
> Keep sleeping SPI and regmap accesses outside the locked region, and keep
> the FSL LPUART completion lock held through its wakeup. Acquire the port
> lock after releasing private channel locks to preserve the ordering used
> by UART callbacks. In the MUX timer, publish available FIFO space under
> the port lock and keep the hardware FIFO-drain wait outside it.
> 
> Use IRQ-safe locking in the Atmel RX and TX tasklets and SB1250 termios
> path, since their interrupt handlers now acquire the same port lock.
> Preserve the caller's interrupt state when releasing those locks.
> 
> [ ... ]
> This serializes write notifications with port-locked serial-core state
> changes, allowing readiness and transmit-storage reservations to gate the
> notification without a check-versus-shutdown race.
> 
> Signed-off-by: James Hilliard <james.hilliard1@gmail.com>

Sashiko has reviewed this patch and found no issues.

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