5ab9b2bc8a
[ Upstream commit 77f88abd4a6f73a1a68dbdc0e3f21575fd508fc3 ]
The API of pci_alloc_irq_vectors_affinity() says it returns -ENOSPC if
fewer than @min_vecs interrupt vectors are available for @dev.
However, if a device supports MSI-X but not MSI and a caller requests
@min_vecs that can't be satisfied by MSI-X, we previously returned -EINVAL
(from the failed attempt to enable MSI), not -ENOSPC.
When -ENOSPC is returned, callers may reduce the number IRQs they request
and try again. Most callers can use the @min_vecs and @max_vecs
parameters to avoid this retry loop, but that doesn't work when using IRQ
affinity "nr_sets" because rebalancing the sets is driver-specific.
This return value bug has been present since pci_alloc_irq_vectors() was
added in v4.10 by aff171641d18 ("PCI: Provide sensible IRQ vector
alloc/free routines"), but it wasn't an issue because @min_vecs/@max_vecs
removed the need for callers to iteratively reduce the number of IRQs
requested and retry the allocation, so they didn't need to distinguish
-ENOSPC from -EINVAL.
In v5.0, 6da4b3ab9a6e ("genirq/affinity: Add support for allocating
interrupt sets") added IRQ sets to the interface, which reintroduced the
need to check for -ENOSPC and possibly reduce the number of IRQs requested
and retry the allocation.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
[bhelgaas: changelog]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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.