dynamic printk

hi,

Add the ability to dynamically enable/disable pr_debug()/dev_dbg() in the kernel. Yes, these calls could be converted to printk(KERN_DEBUG), but there are enough to cause overhead. Additionally, the logs become difficult to read. Here, one can turn on and off these messages per .c source file via:

echo "add file.c" > /sys/kernel/debug/dynamic_printk/files echo "remove file.c" > /sys/kernel/debug/dynamic_printk/files

There is also a special 'all' value that turns on all the debugging messages.

I hope that these patches are useful for people writing new kernel code, for system debugging and testing. In enabling the 'all' feature on the kernel I was running i got a bunch of messages... (i'm not sure what they mean, but they could point out an error or a kernel optimization that could be made, which I didn't necessarily know about otherwise).

thanks,

-Jason

Apr  1 10:33:38 dhcp83-106 kernel: Already setup manip DST for ct ffff81007d800140
Apr  1 10:33:38 dhcp83-106 kernel: Already setup manip SRC for ct ffff81007d800140
Apr  1 10:33:38 dhcp83-106 kernel: Already setup manip DST for ct ffff81007d800a00
Apr  1 10:33:38 dhcp83-106 kernel: Already setup manip SRC for ct ffff81007d800a00
Apr  1 10:33:39 dhcp83-106 kernel: Already setup manip DST for ct ffff81007d800a00
Apr  1 10:33:39 dhcp83-106 kernel: Already setup manip SRC for ct ffff81007d800a00
Apr  1 10:33:39 dhcp83-106 kernel: Already setup manip DST for ct ffff81007d800a00
Apr  1 10:33:39 dhcp83-106 kernel: Already setup manip SRC for ct ffff81007d800a00
Apr  1 10:33:40 dhcp83-106 kernel: Already setup manip DST for ct ffff810071851dc0
Apr  1 10:33:40 dhcp83-106 kernel: Already setup manip SRC for ct ffff810071851dc0
Apr  1 10:33:40 dhcp83-106 kernel: Already setup manip DST for ct ffff81007d800a00
Apr  1 10:33:40 dhcp83-106 kernel: Already setup manip SRC for ct ffff81007d800a00