mirror of
https://github.com/Fishwaldo/Star64_linux.git
synced 2025-07-02 20:29:20 +00:00
No description
363e934d88
timer_base::must_forward_clock is indicating that the base clock might be stale due to a long idle sleep. The forwarding of the base clock takes place in the timer softirq or when a timer is enqueued to a base which is idle. If the enqueue of timer to an idle base happens from a remote CPU, then the following race can happen: CPU0 CPU1 run_timer_softirq mod_timer base = lock_timer_base(timer); base->must_forward_clk = false if (base->must_forward_clk) forward(base); -> skipped enqueue_timer(base, timer, idx); -> idx is calculated high due to stale base unlock_timer_base(timer); base = lock_timer_base(timer); forward(base); The root cause is that timer_base::must_forward_clk is cleared outside the timer_base::lock held region, so the remote queuing CPU observes it as cleared, but the base clock is still stale. This can cause large granularity values for timers, i.e. the accuracy of the expiry time suffers. Prevent this by clearing the flag with timer_base::lock held, so that the forwarding takes place before the cleared flag is observable by a remote CPU. Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: john.stultz@linaro.org Cc: sboyd@kernel.org Cc: linux-arm-msm@vger.kernel.org Link: https://lkml.kernel.org/r/1533199863-22748-1-git-send-email-gkohli@codeaurora.org |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| 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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.