unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
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Linux kernel modifications for the Kernel Hacking exam
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Michael S. Tsirkin 2145ab513e virtio_pci: use irq to detect interrupt support 
commit 71491c54ea ("virtio_pci: don't try to use intxif pin is zero")
breaks virtio_pci on powerpc, when running as a qemu guest.

vp_find_vqs() bails out because pci_dev->pin == 0.

But pci_dev->irq is populated correctly, so vp_find_vqs_intx() would
succeed if we called it - which is what the code used to do.

This seems to happen because pci_dev->pin is not populated in
pci_assign_irq(). A PCI core bug? Maybe.

However Linus said:
	I really think that that is basically the only time you should use
	that 'pci_dev->pin' thing: it basically exists not for "does this
	device have an IRQ", but for "what is the routing of this irq on this
	device".

and
	The correct way to check for "no irq" doesn't use NO_IRQ at all, it just does
		if (dev->irq) ...

so let's just check irq and be done with it.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Fixes: 71491c54ea ("virtio_pci: don't try to use intxif pin is zero")
Cc: "Angus Chen" <angus.chen@jaguarmicro.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221012220312.308522-1-mst@redhat.com>
2022-10-13 09:33:03 -04:00
arch These are the pin control changes for the v6.1 kernel cycle: 2022-10-11 10:59:59 -07:00
block - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
Documentation pci-v6.1-changes 2022-10-11 11:08:18 -07:00
drivers virtio_pci: use irq to detect interrupt support 2022-10-13 09:33:03 -04:00
fs xfs: changes for 6.1-rc1 2022-10-10 20:32:10 -07:00
include pci-v6.1-changes 2022-10-11 11:08:18 -07:00
init - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
io_uring for-6.1/passthrough-2022-10-04 2022-10-07 09:35:50 -07:00
ipc - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
kernel gfs2 debugfs improvements 2022-10-10 20:13:22 -07:00
lib - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
LICENSES
mm tmpfile API change 2022-10-10 19:45:17 -07:00
net 9p-for-6.1: smaller buffers for small messages and fixes 2022-10-10 20:21:09 -07:00
rust Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
samples Tracing updates for 6.1: 2022-10-10 12:20:55 -07:00
scripts - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
security - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
sound sound updates for 6.1-rc1 2022-10-05 12:02:07 -07:00
tools - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
usr
virt KVM: remove KVM_REQ_UNHALT 2022-09-26 12:37:21 -04:00
.clang-format
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap The first batch of KVM patches, mostly covering x86, which I 2022-10-09 09:39:55 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS pci-v6.1-changes 2022-10-11 11:08:18 -07:00
Makefile - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
README

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.