3 Commits

Author	SHA1	Message	Date
Steven Rostedt (VMware)	da5afbeb17	ftrace: Optimize testing what context current is in ... The preempt_count() is not a simple location in memory, it could be part of per_cpu code or more. Each access to preempt_count(), or one of its accessor functions (like in_interrupt()) takes several cycles. By reading preempt_count() once, and then doing tests to find the context against the value return is slightly faster than using in_nmi() and in_interrupt(). Link: https://lkml.kernel.org/r/20201028115612.780796355@goodmis.org Link: https://lkml.kernel.org/r/20201106023546.558881845@goodmis.org Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>	2020-11-06 08:33:23 -05:00
Steven Rostedt (VMware)	6e4eb9cb22	ftrace: Add ftrace_test_recursion_trylock() helper function ... To make it easier for ftrace callbacks to have recursion protection, provide a ftrace_test_recursion_trylock() and ftrace_test_recursion_unlock() helper that tests for recursion. Link: https://lkml.kernel.org/r/20201028115612.634927593@goodmis.org Link: https://lkml.kernel.org/r/20201106023546.378584067@goodmis.org Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>	2020-11-06 08:33:23 -05:00
Steven Rostedt (VMware)	0264c8c9e1	ftrace: Move the recursion testing into global headers ... Currently, if a callback is registered to a ftrace function and its ftrace_ops does not have the RECURSION flag set, it is encapsulated in a helper function that does the recursion for it. Really, all the callbacks should have their own recursion protection for performance reasons. But they should not all implement their own. Move the recursion helpers to global headers, so that all callbacks can use them. Link: https://lkml.kernel.org/r/20201028115612.460535535@goodmis.org Link: https://lkml.kernel.org/r/20201106023546.166456258@goodmis.org Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>	2020-11-06 08:33:23 -05:00