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Commit 16d79d7d authored by Nils Carlson's avatar Nils Carlson Committed by David S. Miller
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bonding 802.3ad: Fix the state machine locking v2 



Changes since v1:
* Clarify an unclear comment
* Move a (possible) name change to a separate patch

The ad_rx_machine, ad_periodic_machine and ad_port_selection_logic
functions all inspect and alter common fields within the port structure.
Previous to this patch, only the ad_rx_machines were mutexed, and the
periodic and port_selection could run unmutexed against an ad_rx_machine
trigged by an arriving LACPDU.

This patch remedies the situation by protecting all the state machines
from concurrency. This is accomplished by locking around all the state
machines for a given port, which are executed at regular intervals; and
the ad_rx_machine when handling an incoming LACPDU.

Signed-off-by: default avatarNils Carlson <nils.carlson@ericsson.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ce3c8692

drivers/net/bonding/bond_3ad.c

+11 −5
Original line number Diff line number Diff line
@@ -1025,9 +1025,6 @@ static void ad_rx_machine(struct lacpdu *lacpdu, struct port *port) 
{

	rx_states_t last_state;



	// Lock to prevent 2 instances of this function to run simultaneously(rx interrupt and periodic machine callback)

	__get_rx_machine_lock(port);



	// keep current State Machine state to compare later if it was changed

	last_state = port->sm_rx_state;
@@ -1133,7 +1130,6 @@ static void ad_rx_machine(struct lacpdu *lacpdu, struct port *port) 
				pr_err("%s: An illegal loopback occurred on adapter (%s).\n"

				       "Check the configuration to verify that all adapters are connected to 802.3ad compliant switch ports\n",

				       port->slave->dev->master->name, port->slave->dev->name);

				__release_rx_machine_lock(port);

				return;

			}

			__update_selected(lacpdu, port);
@@ -1153,7 +1149,6 @@ static void ad_rx_machine(struct lacpdu *lacpdu, struct port *port) 
			break;

		}

	}

	__release_rx_machine_lock(port);

}



/**
@@ -2155,6 +2150,12 @@ void bond_3ad_state_machine_handler(struct work_struct *work) 
			goto re_arm;

		}



		/* Lock around state machines to protect data accessed

		 * by all (e.g., port->sm_vars).  ad_rx_machine may run

		 * concurrently due to incoming LACPDU.

		 */

		__get_rx_machine_lock(port);



		ad_rx_machine(NULL, port);

		ad_periodic_machine(port);

		ad_port_selection_logic(port);
@@ -2164,6 +2165,8 @@ void bond_3ad_state_machine_handler(struct work_struct *work) 
		// turn off the BEGIN bit, since we already handled it

		if (port->sm_vars & AD_PORT_BEGIN)

			port->sm_vars &= ~AD_PORT_BEGIN;



		__release_rx_machine_lock(port);

	}



re_arm:
@@ -2200,7 +2203,10 @@ static void bond_3ad_rx_indication(struct lacpdu *lacpdu, struct slave *slave, u 
		case AD_TYPE_LACPDU:

			pr_debug("Received LACPDU on port %d\n",

				 port->actor_port_number);

			/* Protect against concurrent state machines */

			__get_rx_machine_lock(port);

			ad_rx_machine(lacpdu, port);

			__release_rx_machine_lock(port);

			break;



		case AD_TYPE_MARKER: