Kernel Source and devicetree for NOTHING Phone(3a) and Phone(3a)Pro
74db59e63b
commit a30badfd7c13fc8763a9e10c5a12ba7f81515a55 upstream. On unplug of a Xen console, xencons_disconnect_backend() unconditionally calls free_irq() via unbind_from_irqhandler(), causing a warning of freeing an already-free IRQ: (qemu) device_del con1 [ 32.050919] ------------[ cut here ]------------ [ 32.050942] Trying to free already-free IRQ 33 [ 32.050990] WARNING: CPU: 0 PID: 51 at kernel/irq/manage.c:1895 __free_irq+0x1d4/0x330 It should be using evtchn_put() to tear down the event channel binding, and let the Linux IRQ side of it be handled by notifier_del_irq() through the HVC code. On which topic... xencons_disconnect_backend() should call hvc_remove() *first*, rather than tearing down the event channel and grant mapping while they are in use. And then the IRQ is guaranteed to be freed by the time it's torn down by evtchn_put(). Since evtchn_put() also closes the actual event channel, avoid calling xenbus_free_evtchn() except in the failure path where the IRQ was not successfully set up. However, calling hvc_remove() at the start of xencons_disconnect_backend() still isn't early enough. An unplug request is indicated by the backend setting its state to XenbusStateClosing, which triggers a notification to xencons_backend_changed(), which... does nothing except set its own frontend state directly to XenbusStateClosed without *actually* tearing down the HVC device or, you know, making sure it isn't actively in use. So the backend sees the guest frontend set its state to XenbusStateClosed and stops servicing the interrupt... and the guest spins for ever in the domU_write_console() function waiting for the ring to drain. Fix that one by calling hvc_remove() from xencons_backend_changed() before signalling to the backend that it's OK to proceed with the removal. Tested with 'dd if=/dev/zero of=/dev/hvc1' while telling Qemu to remove the console device. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20231020161529.355083-4-dwmw2@infradead.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.