Commit 1b26d364 authored Jan 06, 2022 by Vladimir Oltean Committed by David S. Miller Jan 06, 2022

net: dsa: warn about dsa_port and dsa_switch bit fields being non atomic

As discussed during review here:
https://patchwork.kernel.org/project/netdevbpf/patch/20220105132141.2648876-3-vladimir.oltean@nxp.com/



we should inform developers about pitfalls of concurrent access to the
boolean properties of dsa_switch and dsa_port, now that they've been
converted to bit fields. No other measure than a comment needs to be
taken, since the code paths that update these bit fields are not
concurrent with each other.

Suggested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 63cfc657

include/net/dsa.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -265,6 +265,10 @@ struct dsa_port {

		u8 stp_state;

		/* Warning: the following bit fields are not atomic, and updating them
		* can only be done from code paths where concurrency is not possible
		* (probe time or under rtnl_lock).
		*/
		u8 vlan_filtering:1;

		/* Managed by DSA on user ports and by drivers on CPU and DSA ports */
		@@ -333,6 +337,10 @@ struct dsa_switch {
		struct dsa_switch_tree *dst;
		unsigned int index;

		/* Warning: the following bit fields are not atomic, and updating them
		* can only be done from code paths where concurrency is not possible
		* (probe time or under rtnl_lock).
		*/
		u32 setup:1;

		/* Disallow bridge core from requesting different VLAN awareness