From: Peter Hurley <peter@hurleysoftware.com>
Date: Tue, 2 Sep 2014 21:39:19 +0000 (-0400)
Subject: serial: core: Document lock requirement for UPF_* flags updates
X-Git-Tag: v4.14-rc1~6738^2~64
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=8a949b07e4062cbd07e04e6a47249e69ca65b944;p=platform%2Fkernel%2Flinux-rpi.git

serial: core: Document lock requirement for UPF_* flags updates

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@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index cf3a1e7..8cb267b 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))