Serialized access to an i/o adapter through atomic operation

A computer program product of enqueuing one or more packets in a device driver for an I/O adapter, the computer program product comprising:

• a computer usable medium having computer usable program code embodied therewith, the computer program product comprising:
• computer usable program code configured to receive, by a processor executing the device driver, a reference to a list of transmit packets;
• computer usable program code configured to atomically fetch and set a transmit active flag, wherein atomically fetching and setting comprises determining a former status of the transmit active flag;
• computer usable program code configured to atomically remove, by a processor executing the device driver, any packets referenced by a host machine transmit queue reference, responsive to a determination that a former status of the transmit active flag is different than a current status of the transmit active flag;
• computer usable program code pre-pending transmit packets referenced by the host machine transmit queue reference to the list of transmit packets to form an augmented list of transmit packets;
• computer usable program code configured to build a work request based on the augmented list of transmit packets;
• computer usable program code configured to notify the I/O adapter of the work request;
• and
• computer usable program code configured to atomically reset the transmit active flag.

A data processing system comprising:

• a bus;
• a storage device connected to the bus, wherein computer usable code is located in the storage device;
• a communication unit connected to the bus;
• and
• a processing unit connected to the bus, wherein the processing unit executes the computer usable code for enqueuing one or more packets in a device driver for an I/O adapter, the processing unit further executes the computer usable code to receive, by a processor executing the device driver, a reference to a list of transmit packets;
• atomically fetch and set a transmit active flag, wherein atomically fetching and setting comprises determining a former status of the transmit active flag;
• atomically remove, by a processor executing the device driver, any packets referenced by a host machine transmit queue reference, responsive to a determination that a former status of the transmit active flag is different than a current status of the transmit active flag;
• pre-pending transmit packets referenced by the host machine transmit queue reference to the list of transmit packets to form an augmented list of transmit packets;
• build a work request based on the augmented list of transmit packets;
• notify the I/O adapter of the work request;
• and atomically reset the transmit active flag.