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This is a micro-optimization, but as it has to deal with a fast path of the function tracer, these optimizations can be noticed. The ftrace_lookup_ip() returns true if the given ip is found in the hash. If it's not found or the hash is NULL, it returns false. But there's some cases that a NULL hash is a true, and the ftrace_hash_empty() is tested before calling ftrace_lookup_ip() in those cases. But as ftrace_lookup_ip() tests that first, that adds a few extra unneeded instructions in those cases. A new static "always_inlined" function is created that does not perform the hash empty test. This most only be used by callers that do the check first anyway, as an empty or NULL hash could cause a crash if a lookup is performed on it. Also add kernel doc for the ftrace_lookup_ip() main function. Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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.