[Xen-devel] [PATCH] pciback: deferred handling of pci configuration space accesses

[Ryan <hap9@xxxxxxxxxxxxxx>]

Some of the Linux PCI functions called by the virtual configuration
space handlers were making calls into ACPI code which uses semaphores.
Since semaphores can not be locked while atomic (because they could
sleep), I changed the way the PCI backend responds to requests from the
frontend. Previously, the virtual configuration space handlers ran in
the same context as the event channel interrupt handler (which was often
atomic if not always atomic). Now the interrupt handler schedules a
callback function (a bottom half) in the system work queue (keventd)
that will get called in process context at a slightly later time. This
allows the handlers in the virtual configuration space to run in process
context and to call any core PCI function regardless of whether it will
sleep or not.

This patch was previously submitted as part of a larger patch. There
have been no significant changes, just renamed a variable and made this
code independent of the other patch.

Signed-off-by: Ryan Wilson <hap9@xxxxxxxxxxxxxx>

Attachment: pciback_op_workqueue.patch
Description: Text Data

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