necessary locking using port->lock. There are some exceptions (which
are described in the uart_ops listing below.)
-There are three locks. A per-port spinlock, a per-port tmpbuf semaphore,
-and an overall semaphore.
+There are two locks. A per-port spinlock, and an overall semaphore.
From the core driver perspective, the port->lock locks the following
data:
The low level driver is free to use this lock to provide any additional
locking.
-The core driver uses the info->tmpbuf_sem lock to prevent multi-threaded
-access to the info->tmpbuf bouncebuffer used for port writes.
-
The port_sem semaphore is used to protect against ports being added/
removed or reconfigured at inappropriate times. Since v2.6.27, this
semaphore has been the 'mutex' member of the tty_port struct, and