lkml.org 
[lkml]   [2013]   [Feb]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v6 20/46] net: Use get/put_online_cpus_atomic() to prevent CPU offline
    Date
    Once stop_machine() is gone from the CPU offline path, we won't be able to
    depend on preempt_disable() or local_irq_disable() to prevent CPUs from
    going offline from under us.

    Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline,
    while invoking from atomic context.

    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: Eric Dumazet <edumazet@google.com>
    Cc: netdev@vger.kernel.org
    Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
    ---

    net/core/dev.c | 9 +++++++--
    1 file changed, 7 insertions(+), 2 deletions(-)

    diff --git a/net/core/dev.c b/net/core/dev.c
    index f64e439..5421f96 100644
    --- a/net/core/dev.c
    +++ b/net/core/dev.c
    @@ -3089,7 +3089,7 @@ int netif_rx(struct sk_buff *skb)
    struct rps_dev_flow voidflow, *rflow = &voidflow;
    int cpu;

    - preempt_disable();
    + get_online_cpus_atomic();
    rcu_read_lock();

    cpu = get_rps_cpu(skb->dev, skb, &rflow);
    @@ -3099,7 +3099,7 @@ int netif_rx(struct sk_buff *skb)
    ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);

    rcu_read_unlock();
    - preempt_enable();
    + put_online_cpus_atomic();
    } else
    #endif
    {
    @@ -3498,6 +3498,7 @@ int netif_receive_skb(struct sk_buff *skb)
    struct rps_dev_flow voidflow, *rflow = &voidflow;
    int cpu, ret;

    + get_online_cpus_atomic();
    rcu_read_lock();

    cpu = get_rps_cpu(skb->dev, skb, &rflow);
    @@ -3505,9 +3506,11 @@ int netif_receive_skb(struct sk_buff *skb)
    if (cpu >= 0) {
    ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
    rcu_read_unlock();
    + put_online_cpus_atomic();
    return ret;
    }
    rcu_read_unlock();
    + put_online_cpus_atomic();
    }
    #endif
    return __netif_receive_skb(skb);
    @@ -3887,6 +3890,7 @@ static void net_rps_action_and_irq_enable(struct softnet_data *sd)
    local_irq_enable();

    /* Send pending IPI's to kick RPS processing on remote cpus. */
    + get_online_cpus_atomic();
    while (remsd) {
    struct softnet_data *next = remsd->rps_ipi_next;

    @@ -3895,6 +3899,7 @@ static void net_rps_action_and_irq_enable(struct softnet_data *sd)
    &remsd->csd, 0);
    remsd = next;
    }
    + put_online_cpus_atomic();
    } else
    #endif
    local_irq_enable();


    \
     
     \ /
      Last update: 2013-02-18 14:42    [W:4.090 / U:0.000 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site