[linux-yocto] [PATCH] Revert "igb: reduce CPU0 latency when updating statistics"

[He Zhe]

On 1/21/19 9:47 PM, Bruce Ashfield wrote:
> Which kernel/bsp branch is this one for ? I'm about to push an
> update to linux-yocto-dev today, so from the comment below, it
> looks like we are already covered ?

This is for standard/base. It's from v5.0-rc3.

Zhe

>
> Bruce
>
> On 1/21/19 5:09 AM, zhe.he at windriver.com wrote:
>> From: Jeff Kirsher <jeffrey.t.kirsher at intel.com>
>>
>> This reverts commit 59361316afcb08569af21e1af83e89c7051c055a.
>>
>> Due to problems found in additional testing, this causes an illegal
>> context switch in the RCU read-side critical section.
>>
>> CC: Dave Jones <davej at codemonkey.org.uk>
>> CC: Cong Wang <xiyou.wangcong at gmail.com>
>> CC: Jan Jablonsky <jan.jablonsky at thalesgroup.com>
>> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher at intel.com>
>> Signed-off-by: David S. Miller <davem at davemloft.net>
>>
>> commit 5642e27bf6a935c1d0d9149e83d625dfba286463 upstream
>>
>> Before syncing up with 5.0-rc3, it's worth backporting this patch which fixes
>> the following serious crash.
>>
>> BUG: sleeping function called from invalid context at kernel/locking/mutex.c:254
>> in_atomic(): 0, irqs_disabled(): 0, pid: 7867, name: ifconfig
>> Preemption disabled at:
>> [<ffffffffa24962ce>] memcg_kmem_put_cache+0x2e/0x70
>> ---- snip ----
>> Call Trace:
>>   dump_stack+0x4f/0x6a
>>   ? memcg_kmem_put_cache+0x2e/0x70
>>   ___might_sleep.cold.17+0xd9/0xea
>>   __might_sleep+0x4a/0x80
>>   mutex_lock+0x20/0x40
>>   igb_get_stats64+0x2c/0x60
>>   dev_get_stats+0x3f/0xa0
>>   dev_seq_printf_stats+0x37/0xe0
>>   dev_seq_show+0x14/0x30
>>   seq_read+0x2d3/0x3e0
>>   proc_reg_read+0x3e/0x60
>>   __vfs_read+0x3a/0x180
>>   ? security_file_permission+0x9c/0xf0
>>   vfs_read+0xa1/0x160
>>   ksys_read+0x55/0xc0
>>   __x64_sys_read+0x1a/0x20
>>   do_syscall_64+0x4d/0xf0
>>   entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>
>> Signed-off-by: He Zhe <zhe.he at windriver.com>
>> ---
>>   drivers/net/ethernet/intel/igb/igb.h         |  2 +-
>>   drivers/net/ethernet/intel/igb/igb_ethtool.c |  4 ++--
>>   drivers/net/ethernet/intel/igb/igb_main.c    | 14 +++++++-------
>>   3 files changed, 10 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h
>> index fe1592a..ca54e26 100644
>> --- a/drivers/net/ethernet/intel/igb/igb.h
>> +++ b/drivers/net/ethernet/intel/igb/igb.h
>> @@ -515,7 +515,7 @@ struct igb_adapter {
>>       /* OS defined structs */
>>       struct pci_dev *pdev;
>>   -    struct mutex stats64_lock;
>> +    spinlock_t stats64_lock;
>>       struct rtnl_link_stats64 stats64;
>>         /* structs defined in e1000_hw.h */
>> diff --git a/drivers/net/ethernet/intel/igb/igb_ethtool.c b/drivers/net/ethernet/intel/igb/igb_ethtool.c
>> index 7426060..c576710 100644
>> --- a/drivers/net/ethernet/intel/igb/igb_ethtool.c
>> +++ b/drivers/net/ethernet/intel/igb/igb_ethtool.c
>> @@ -2295,7 +2295,7 @@ static void igb_get_ethtool_stats(struct net_device *netdev,
>>       int i, j;
>>       char *p;
>>   -    mutex_lock(&adapter->stats64_lock);
>> +    spin_lock(&adapter->stats64_lock);
>>       igb_update_stats(adapter);
>>         for (i = 0; i < IGB_GLOBAL_STATS_LEN; i++) {
>> @@ -2338,7 +2338,7 @@ static void igb_get_ethtool_stats(struct net_device *netdev,
>>           } while (u64_stats_fetch_retry_irq(&ring->rx_syncp, start));
>>           i += IGB_RX_QUEUE_STATS_LEN;
>>       }
>> -    mutex_unlock(&adapter->stats64_lock);
>> +    spin_unlock(&adapter->stats64_lock);
>>   }
>>     static void igb_get_strings(struct net_device *netdev, u32 stringset, u8 *data)
>> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
>> index 87bdf16..7137e7f 100644
>> --- a/drivers/net/ethernet/intel/igb/igb_main.c
>> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
>> @@ -2203,9 +2203,9 @@ void igb_down(struct igb_adapter *adapter)
>>       del_timer_sync(&adapter->phy_info_timer);
>>         /* record the stats before reset*/
>> -    mutex_lock(&adapter->stats64_lock);
>> +    spin_lock(&adapter->stats64_lock);
>>       igb_update_stats(adapter);
>> -    mutex_unlock(&adapter->stats64_lock);
>> +    spin_unlock(&adapter->stats64_lock);
>>         adapter->link_speed = 0;
>>       adapter->link_duplex = 0;
>> @@ -3840,7 +3840,7 @@ static int igb_sw_init(struct igb_adapter *adapter)
>>       adapter->min_frame_size = ETH_ZLEN + ETH_FCS_LEN;
>>         spin_lock_init(&adapter->nfc_lock);
>> -    mutex_init(&adapter->stats64_lock);
>> +    spin_lock_init(&adapter->stats64_lock);
>>   #ifdef CONFIG_PCI_IOV
>>       switch (hw->mac.type) {
>>       case e1000_82576:
>> @@ -5406,9 +5406,9 @@ static void igb_watchdog_task(struct work_struct *work)
>>           }
>>       }
>>   -    mutex_lock(&adapter->stats64_lock);
>> +    spin_lock(&adapter->stats64_lock);
>>       igb_update_stats(adapter);
>> -    mutex_unlock(&adapter->stats64_lock);
>> +    spin_unlock(&adapter->stats64_lock);
>>         for (i = 0; i < adapter->num_tx_queues; i++) {
>>           struct igb_ring *tx_ring = adapter->tx_ring[i];
>> @@ -6235,10 +6235,10 @@ static void igb_get_stats64(struct net_device *netdev,
>>   {
>>       struct igb_adapter *adapter = netdev_priv(netdev);
>>   -    mutex_lock(&adapter->stats64_lock);
>> +    spin_lock(&adapter->stats64_lock);
>>       igb_update_stats(adapter);
>>       memcpy(stats, &adapter->stats64, sizeof(*stats));
>> -    mutex_unlock(&adapter->stats64_lock);
>> +    spin_unlock(&adapter->stats64_lock);
>>   }
>>     /**
>>
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