mirror of https://gitee.com/openkylin/linux.git
8442ef6f11
During suspend/resume usecases and tests, it is common to see issues such as lockups either in suspend path or resume path because of the bugs in the corresponding device driver pm handling code. In such cases, it is important that watchdog is active to make sure that we either receive a watchdog pretimeout notification or a bite causing reset instead of a hang causing us to hard reset the machine. There are good reasons as to why we need this because: * We can have a watchdog pretimeout governor set to panic in which case we can have a backtrace which would help identify the issue with the particular driver and cause a normal reboot. * Even in case where there is no pretimeout support, a watchdog bite is still useful because some firmware has debug support to dump CPU core context on watchdog bite for post-mortem analysis. * One more usecase which comes to mind is of warm reboot. In case we hard reset the target, a cold reboot could be induced resulting in lose of ddr contents thereby losing all the debug info. Currently, the watchdog pm callback just invokes the usual suspend and resume callback which do not have any special ordering in the sense that a watchdog can be suspended before the buggy device driver suspend callback and watchdog resume can happen after the buggy device driver resume callback. This would mean that the watchdog will not be active when the buggy driver cause the lockups thereby hanging the system. So to make sure this doesn't happen, move the watchdog pm to use late/early system pm callbacks which will ensure that the watchdog is suspended late and resumed early so that it can catch such issues. Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Douglas Anderson <dianders@chromium.org> Link: https://lore.kernel.org/r/20210310202004.1436-1-saiprakash.ranjan@codeaurora.org Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org> |
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| arch | ||
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| 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 | ||
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| 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.