trace_softirq_entry — called immediately before the softirq handler
void trace_softirq_entry ( | struct softirq_action * h, |
struct softirq_action * vec); |
hpointer to struct softirq_action
vecpointer to first struct softirq_action in softirq_vec array
The h parameter, contains a pointer to the struct softirq_action
which has a pointer to the action handler that is called. By subtracting
the vec pointer from the h pointer, we can determine the softirq
number. Also, when used in combination with the softirq_exit tracepoint
we can determine the softirq latency.