1a149d7d3f
The current method to prevent the ring buffer from entering into a recursize loop is to use a bitmask and set the bit that maps to the current context (normal, softirq, irq or NMI), and if that bit was already set, it is considered a recursive loop. New code is being added that may require the ring buffer to be entered a second time in the current context. The recursive locking prevents that from happening. Instead of mapping a bitmask to the current context, just allow 4 levels of nesting in the ring buffer. This matches the 4 context levels that it can already nest. It is highly unlikely to have more than two levels, thus it should be fine when we add the second entry into the ring buffer. If that proves to be a problem, we can always up the number to 8. An added benefit is that reading preempt_count() to get the current level adds a very slight but noticeable overhead. This removes that need. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> |
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README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.