On Tue, Nov 22, 2022 at 07:53:23AM -0800, ira.weiny@xxxxxxxxx wrote: > Each struct doe_mb is managed as part of the PCI device. They can't go > away as long as the PCI device exists. pci_doe_flush_mb() was set up to > flush the workqueue and prevent any further submissions to the mailboxes > when the PCI device goes away. Unfortunately, this was fundamentally > flawed. There was no guarantee that a struct doe_mb remained after > pci_doe_flush_mb() returned. Therefore, the doe_mb state could be > invalid when those threads waiting on the workqueue were flushed. > > Fortunately the current code is safe because all callers make a > synchronous call to pci_doe_submit_task() and maintain a reference on the > PCI device. > > For these reasons, pci_doe_flush_mb() will never be called while tasks > are being processed and there is no use for it. Going forward my plan is to allocate all existing DOE mailboxes of a device upon enumeration. That will allow concurrent use of a mailbox by multiple drivers. When a pci_dev goes away, say, because it's been hot-removed, we need a way to abort all ongoing DOE exchanges. pci_doe_flush_mb() seems to do just that so I'm not sure why it's being removed? Thanks, Lukas
