tree e338e750e252c43b776013bb5a6bd7c3d52d4207
parent 2b672caf96ad6f417c83e8bfc0c4fc1a7d91132c
author Colin Cross <ccross@android.com> 1351730499 -0700
committer Dmitry Shmidt <dimitrysh@google.com> 1485553884 -0800

ANDROID: ARM: fiq_debugger: lock between tty and console writes

debug_console_write calls debug_uart_flush, which will usually wait
until the serial port fifo empties.  If another thread is continuously
calling fiq_tty_write, the fifo will constantly be refilled and
debug_uart_flush might never return.

Add a spinlock that is locked in debug_console_write and fiq_tty_write
to ensure they can't run at the same time.  This has an extra advantage
of preventing lines from the console and tty from being mixed together.

Also reduce the size returned by fiq_tty_write_room to keep the time
spent with the spinlock held to a reasonable value.

In addition, make sure fiq context can't loop forever by never calling
debug_uart_flush when the console is enabled.

Change-Id: I5712b01f740ca0c84f680d2032c9fa16b7656939
Signed-off-by: Colin Cross <ccross@android.com>