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- From: Gregory CLEMENT <gregory.clement@free-electrons.com>
- Date: Thu, 4 Feb 2016 22:09:28 +0100
- Subject: [PATCH] net: mvneta: The mvneta_percpu_elect function should be
- atomic
- Electing a CPU must be done in an atomic way: it should be done after or
- before the removal/insertion of a CPU and this function is not reentrant.
- During the loop of mvneta_percpu_elect we associates the queues to the
- CPUs, if there is a topology change during this loop, then the mapping
- between the CPUs and the queues could be wrong. During this loop the
- interrupt mask is also updating for each CPUs, It should not be changed
- in the same time by other part of the driver.
- This patch adds spinlock to create the needed critical sections.
- Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
- Signed-off-by: David S. Miller <davem@davemloft.net>
- ---
- --- a/drivers/net/ethernet/marvell/mvneta.c
- +++ b/drivers/net/ethernet/marvell/mvneta.c
- @@ -370,6 +370,10 @@ struct mvneta_port {
- struct net_device *dev;
- struct notifier_block cpu_notifier;
- int rxq_def;
- + /* Protect the access to the percpu interrupt registers,
- + * ensuring that the configuration remains coherent.
- + */
- + spinlock_t lock;
-
- /* Core clock */
- struct clk *clk;
- @@ -2853,6 +2857,12 @@ static void mvneta_percpu_elect(struct m
- {
- int elected_cpu = 0, max_cpu, cpu, i = 0;
-
- + /* Electing a CPU must be done in an atomic way: it should be
- + * done after or before the removal/insertion of a CPU and
- + * this function is not reentrant.
- + */
- + spin_lock(&pp->lock);
- +
- /* Use the cpu associated to the rxq when it is online, in all
- * the other cases, use the cpu 0 which can't be offline.
- */
- @@ -2896,6 +2906,7 @@ static void mvneta_percpu_elect(struct m
- i++;
-
- }
- + spin_unlock(&pp->lock);
- };
-
- static int mvneta_percpu_notifier(struct notifier_block *nfb,
- @@ -2950,8 +2961,13 @@ static int mvneta_percpu_notifier(struct
- case CPU_DOWN_PREPARE:
- case CPU_DOWN_PREPARE_FROZEN:
- netif_tx_stop_all_queues(pp->dev);
- + /* Thanks to this lock we are sure that any pending
- + * cpu election is done
- + */
- + spin_lock(&pp->lock);
- /* Mask all ethernet port interrupts */
- on_each_cpu(mvneta_percpu_mask_interrupt, pp, true);
- + spin_unlock(&pp->lock);
-
- napi_synchronize(&port->napi);
- napi_disable(&port->napi);
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