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authorSteven Rostedt <srostedt@redhat.com>2009-02-13 20:53:42 -0500
committerSteven Rostedt <srostedt@redhat.com>2009-02-16 17:03:49 -0500
commite68746a271eb3393a2183840be9e903caddf765b (patch)
tree106ea87792837ccee1476687d9f9a067f96488a9 /Documentation/s390/kvm.txt
parent64e7c440618998fd69eee6ab490b042d12248021 (diff)
ftrace: enable filtering only when a function is filtered on
Impact: fix to prevent empty set_ftrace_filter and no ftrace output The function filter is used to only trace a given set of functions. The filter is enabled when a function name is echoed into the set_ftrace_filter file. But if the name has a typo and the function is not found, the filter is enabled, but no function is listed. This makes a confusing situation where set_ftrace_filter is empty but no functions ever get enabled for tracing. For example: # cat /debug/tracing/set_ftrace_filter #### all functions enabled #### # echo bad_name > set_ftrace_filter # cat /debug/tracing/set_ftrace_filter # echo function > current_tracer # cat trace # tracer: nop # # TASK-PID CPU# TIMESTAMP FUNCTION # | | | | | This patch changes that to only enable filtering if a function is set to be filtered on. Now, the filter is not enabled if a bad name is echoed into set_ftrace_filter. Signed-off-by: Steven Rostedt <srostedt@redhat.com>
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