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timekeeping suspend/resume calls read_persistent_clock() which takes rtc_lock. That results in might sleep warnings because at that point we run with interrupts disabled. We cannot convert rtc_lock to a raw spinlock as that would trigger other might sleep warnings. As a workaround we disable the might sleep warnings by setting system_state to SYSTEM_SUSPEND before calling sysdev_suspend() and restoring it to SYSTEM_RUNNING afer sysdev_resume(). There is no lock contention because hibernate / suspend to RAM is single-CPU at this point. In s2idle's case the system_state is set to SYSTEM_SUSPEND before timekeeping_suspend() which is invoked by the last CPU. In the resume case it set back to SYSTEM_RUNNING after timekeeping_resume() which is invoked by the first CPU in the resume case. The other CPUs will block on tick_freeze_lock. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bigeasy: cover s2idle in tick_freeze() / tick_unfreeze()] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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.