[SERIAL] Clean up serial locking when obtaining a reference to a port

The locking for the uart_port is over complicated, and can be
simplified if we introduce a flag to indicate that a port is "dead"
and will be removed.

This also helps the validator because it removes a case of non-nested
unlock ordering.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index c32e60e79dea..bd14858121ea 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -254,6 +254,7 @@ struct uart_port {
 #define UPF_CONS_FLOW           ((__force upf_t) (1 << 23))
 #define UPF_SHARE_IRQ           ((__force upf_t) (1 << 24))
 #define UPF_BOOT_AUTOCONF       ((__force upf_t) (1 << 28))
+#define UPF_DEAD                ((__force upf_t) (1 << 30))
 #define UPF_IOREMAP             ((__force upf_t) (1 << 31))
 
 #define UPF_CHANGE_MASK         ((__force upf_t) (0x17fff))