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

[Bruce Ashfield]

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 ?

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);
>   }
>   
>   /**
>