serial: 8250: lock port for omap8250_restore_regs()

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omap8250_restore_regs() accesses UART_IER. This register is
modified twice by each console write (serial8250_console_write())
under the port lock. However, not all calls to omap8250_restore_regs()
are under the port lock.

Add the missing port locking around omap8250_restore_regs() calls. Add
lockdep notation to the omap8250_restore_regs().

Note that this is not fixing a real problem because the serial devices
are resumed before console printing is enabled.

However, adding this locking allows for clean locking semantics
for omap8250_restore_regs() so that lockdep can be used to identify
possible problems in the future. It also simplifies synchronization
of UART_IER in general by not needing to rely on such implementation
details.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20230525093159.223817-7-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

John Ogness 2023-05-25 11:37:57 +02:06 • committed by Greg Kroah-Hartman

parent 87660fb404

commit 8b45503776

1 changed files with 7 additions and 1 deletions

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drivers/tty/serial/8250/8250_omap.c

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