eacb04ff3c
Currently console_flush_on_panic() will attempt to acquire the console lock when flushing the buffer on panic. If it fails to acquire the lock, it continues anyway because this is the last chance to get any pending records printed. The reason why the console lock was attempted at all was to prevent any other CPUs from acquiring the console lock for printing while the panic CPU was printing. But as of the previous commit, non-panic CPUs will no longer attempt to acquire the console lock in a panic situation. Therefore it is no longer strictly necessary for a panic CPU to acquire the console lock. Avoiding taking the console lock when flushing in panic has the additional benefit of avoiding possible deadlocks due to semaphore usage in NMI context (semaphores are not NMI-safe) and avoiding possible deadlocks if another CPU accesses the semaphore and is stopped while holding one of the semaphore's internal spinlocks. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20230717194607.145135-5-john.ogness@linutronix.de
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.