[PATCH 10/26] serial: core: Document lock requirement for UPF_* flags updates

[Peter Hurley]

The flags field of struct uart_port can only be safely modified
if the port mutex is held; no other lock prevents concurrent
changes from corrupting the field.

Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
 include/linux/serial_core.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 5bbb809..4a43292 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -152,6 +152,7 @@ struct uart_port {
 	unsigned long		sysrq;			/* sysrq timeout */
 #endif
 
+	/* flags must be updated while holding port mutex */
 	upf_t			flags;
 
 #define UPF_FOURPORT		((__force upf_t) (1 << 1))
-- 
2.1.0

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