On Thu, 1 Jun 2017 14:25:51 +0200 Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > On Thu, Jun 01, 2017 at 10:15:24AM +0200, Vlastimil Babka wrote: > > Thanks. I didn't make it clear that the trace_printk() warning is > > there even if the code using it doesn't actually execute (i.e. I > > didn't specify any early_printk bootparam). There are some roastedy > > tricks to detect the potential users, so that the buffers can be > > allocated in advance to allow the first trace_printk() from any > > context, I guess. > > > > I'm not sure if there's a way to change it so that your driver > > reports the trace_printk usage only in response to the bootparam > > (which could also be a safe point to allocate ftrace buffers?). > > No, nor do we want to. There should not be a single caller to > trace_printk() in normal kernels. Correct. If you find a trace_printk() that would be useful in a production environment, then make it a tracepoint. That's why I have that nasty banner, to make sure trace_printk()s are not the "quick way" to add tracepoint hacks. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
