It seems that in the Linux kernel some locking has been added with this commit: https://github.com/torvalds/linux/commit/83d0feffc5695d7dc24c6b8dac9ab265533beb78:

spin_lock_irqsave(&adapter->cmd_lock, flags);

VMXNET3_WRITE_BAR1_REG(adapter, VMXNET3_REG_CMD, VMXNET3_CMD_GET_LINK);

ret = VMXNET3_READ_BAR1_REG(adapter, VMXNET3_REG_CMD);

spin_unlock_irqrestore(&adapter->cmd_lock, flags);

Ciprian.

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Lähettäjä: Ciprian Pascu (Nokia)
Lähetetty: keskiviikko 7. joulukuuta 2022 15.57
Vastaanottaja: users@dpdk.org <users@dpdk.org>; bruce.richardson@intel.com <bruce.richardson@intel.com>
Aihe: DPDK issue with reading the eth interface status?

Hi,

I encountered an issue while using dpdk-20.05 in our VMware based VMs: at times, when sysstat data is collected, dpdk signals that some eth interface is down; this happens occasionally; after sysstat data has been collected, eth interface is signaled as up; I was wondering about these lines in ‘__vmxnet3_dev_link_update’ function:

1251 »·······VMXNET3_WRITE_BAR1_REG(hw, VMXNET3_REG_CMD, VMXNET3_CMD_GET_LINK);

1252 »·······ret = VMXNET3_READ_BAR1_REG(hw, VMXNET3_REG_CMD);

Is this atomic? Could this lead to problems if some other module tries to read something else at about the same time and overwrites the command?

Thanks,

Ciprian.