Messages in this thread | | | Date | Fri, 1 Aug 2008 12:53:17 -0400 (EDT) | From | Steven Rostedt <> | Subject | Re: [PATCH v2 2/2] ftrace: printk formatting infrastructure |
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On Fri, 1 Aug 2008, Randy Dunlap wrote:
> On Fri, 01 Aug 2008 12:26:41 -0400 Steven Rostedt wrote: > > > +/** > > + * ftrace_printk - printf formatting in the ftrace buffer > > + * @fmt - the printf format for printing. > > * @fmt: the printf format for printing > * @ip: <description> > > > + * > > + * Note: __ftrace_printk is an internal function for ftrace_printk and > > + * the @ip is passed in via the ftrace_printk macro.
The above note actually explains this ;-)
Should I move the description to the ftrace_printk macro?
In include/linux/ftrace.h you see:
#ifdef CONFIG_TRACING [...] # define ftrace_printk(x...) __ftrace_printk(_THIS_IP_, x) extern int __ftrace_printk(unsigned long ip, const char *fmt, ...) __attribute__ ((format (printf, 2, 3))); #else [...] static inline int ftrace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 0))) { return 0; } #endif
The true API is ftrace_printk(const char *fmt) and the __ftrace_printk version should not be used.
Do you still think I should document the @ip?
I could also just remove the passing of _THIS_IP_ and use _RET_IP_ inside of ftrace_printk but the _THIS_IP_ seems to be more accurate especially when we have stack unwinding returns.
-- Steve
> > + * > > + * This function allows a kernel developer to debug fast path sections > > + * that printk is not appropriate for. By scattering in various > > + * printk like tracing in the code, a developer can quickly see > > + * where problems are occurring. > > + * > > + * This is intended as a debugging tool for the developer only. > > + * Please reframe from leaving ftrace_printks scattered around in > > + * your code. > > + */ > > +int __ftrace_printk(unsigned long ip, const char *fmt, ...) > > +{ > > > --- > ~Randy > Linux Plumbers Conference, 17-19 September 2008, Portland, Oregon USA > http://linuxplumbersconf.org/ >
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