mainlining shenanigans
47f070a63e
There are deadlocks caused by del_timer_sync(&priv->hang_timer) and
del_timer_sync(&priv->rr_timer) in grcan_close(), one of the deadlocks
are shown below:
(Thread 1) | (Thread 2)
| grcan_reset_timer()
grcan_close() | mod_timer()
spin_lock_irqsave() //(1) | (wait a time)
... | grcan_initiate_running_reset()
del_timer_sync() | spin_lock_irqsave() //(2)
(wait timer to stop) | ...
We hold priv->lock in position (1) of thread 1 and use
del_timer_sync() to wait timer to stop, but timer handler also need
priv->lock in position (2) of thread 2. As a result, grcan_close()
will block forever.
This patch extracts del_timer_sync() from the protection of
spin_lock_irqsave(), which could let timer handler to obtain the
needed lock.
Link: https://lore.kernel.org/all/20220425042400.66517-1-duoming@zju.edu.cn
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| 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 | ||
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.