23f61b9fc5
The ghes registration and refcount is broken in several ways: * ghes_edac_register() returns with success for a 2nd instance even if a first instance's registration is still running. This is not correct as the first instance may fail later. A subsequent registration may not finish before the first. Parallel registrations must be avoided. * The refcount was increased even if a registration failed. This leads to stale counters preventing the device from being released. * The ghes refcount may not be decremented properly on unregistration. Always decrement the refcount once ghes_edac_unregister() is called to keep the refcount sane. * The ghes_pvt pointer is handed to the irq handler before registration finished. * The mci structure could be freed while the irq handler is running. Fix this by adding a mutex to ghes_edac_register(). This mutex serializes instances to register and unregister. The refcount is only increased if the registration succeeded. This makes sure the refcount is in a consistent state after registering or unregistering a device. Note: A spinlock cannot be used here as the code section may sleep. The ghes_pvt is protected by ghes_lock now. This ensures the pointer is not updated before registration was finished or while the irq handler is running. It is unset before unregistering the device including necessary (implicit) memory barriers making the changes visible to other CPUs. Thus, the device can not be used anymore by an interrupt. Also, rename ghes_init to ghes_refcount for better readability and switch to refcount API. A refcount is needed because there can be multiple GHES structures being defined (see ACPI 6.3 specification, 18.3.2.7 Generic Hardware Error Source, "Some platforms may describe multiple Generic Hardware Error Source structures with different notification types, ..."). Another approach to use the mci's device refcount (get_device()) and have a release function does not work here. A release function will be called only for device_release() with the last put_device() call. The device must be deleted *before* that with device_del(). This is only possible by maintaining an own refcount. [ bp: touchups. ] Fixes: |
||
|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.