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Under some circumstances, when dealing with a large number of MAC address or VLAN updates at once, the fm10k driver, particularly the VFs can overload the mailbox with too many messages at once. This results in a mailbox timeout, which causes the driver to initiate a reset. During the reset, we re-send all the same messages that originally caused the timeout. This results in a cycle of resets each triggering a future reset. To fix or avoid this, we introduce a workqueue item which monitors a queue of MAC and VLAN requests. These requests are queued to the end of the list, and we process as a FIFO periodically. Initially we only handle requests for the netdev, but we do handle unicast MAC addresses, multicast MAC addresses, and update VLAN requests. A future patch will add support to use this queue for handling MAC update requests from the VF<->PF mailbox. The MAC/VLAN work item will keep checking to make sure that each request does not overflow the mailbox and cause a timeout. If it might, then the work item will reschedule itself a short time later. This avoids any reset cycle, since we never send the message if the mailbox is not ready. As an alternative, we tried increasing the mailbox message FIFO, but this just delays the problem and results in needless memory waste on the system. Our new message queue is dynamically allocated so only uses as much memory as it needs. Additionally, it need not be contiguous like the Tx and Rx FIFOs. Note that this patch chose to only create a queue for MAC and VLAN messages, since these are the only messages sent in a large enough volume to cause the reset loop. Other messages are very unlikely to overflow the mailbox Tx FIFO so easily. Signed-off-by: Jacob Keller <jacob.e.keller@intel.com> Tested-by: Krishneil Singh <krishneil.k.singh@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.