kernel-dynamic-debug

$ mount -t debugfs none /sys/kernel/debug
$ echo h > /proc/sysrq-trigger
$ echo 8 > /proc/sysrq-trigger
$ echo 'file ping.c line 994 +p' >/sys/kernel/debug/dynamic_debug/control
$ dmesg -c
$ ping -c 1 localhost
no socket, dropping
$ echo 'file ping.c +p' >/sys/kernel/debug/dynamic_debug/control
$ dmesg -c
$ ping -c 1 localhost
ping_rcv(skb=c7ba5540,id=8e00,seq=0000)
hash(36352) = 50
try to find: num = 36352, daddr = 127.0.0.1, dif = 1
no socket, dropping
$ echo 'file ping.c +pflmt' >/sys/kernel/debug/dynamic_debug/control
$ dmesg -c
$ ping -c 1 localhost
 ping:ping_rcv:979: ping_rcv(skb=c7ba5600,id=a000,seq=0000)
 ping:ping_hashfn:71: hash(40960) = 50
 ping:ping_lookup:184: try to find: num = 40960, daddr = 127.0.0.1, dif = 1
 ping:ping_rcv:994: no socket, dropping

cmdline:
pc87360.dyndbg="func pc87360_init_device +p; func pc87360_find +p"

echo '-p' >/sys/kernel/debug/dynamic_debug/control

echo 'file serial_core.c +p' >/sys/kernel/debug/dynamic_debug/control