Messages in this thread | | | Date | Fri, 13 Apr 2012 10:35:59 -0400 (EDT) | From | Alan Stern <> | Subject | Re: ehci dynamic debug problem |
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On Fri, 13 Apr 2012, Johannes Stezenbach wrote:
> Hi, > > I have a quirky device and enabled dynamic debug to > see the ehci driver debug messages to help me diagnose > the problem. I see stuff like this: > > [1790542.363321] ehci_hub_control:940: ehci_hcd 0000:00:1a.0: \xffffffd8\xffffff94\xffffff94\xffffffa8\xffffff81\xffffffff\xffffffff\xffffffff\xffffffff}[<\xffffff81\xffffffff\xffffffff\xffffffff\xffffffff\x01 > [1790542.363470] ehci_hub_control:940: ehci_hcd 0000:00:1a.0: \xffffffd8\xffffff94\xffffff94\xffffffa8\xffffff81\xffffffff\xffffffff\xffffffff\xffffffff}[<\xffffff81\xffffffff\xffffffff\xffffffff\xffffffff\x01 > > The problem is in ehci-dbg.c: > > #define dbg_port(ehci, label, port, status) { \ > char _buf [80]; \ > dbg_port_buf (_buf, sizeof _buf, label, port, status); \ > ehci_dbg (ehci, "%s\n", _buf); \ > } > > dbg_port_buf() is a no op when DEBUG is not defined, thus > the ehci_dbg() prints uninitialized memory.
Interesting. I have never run across this, because I never use dynamic debug.
> Does dynamic debug offer an "is the message two lines below enabled" test? > Simply changing the "#ifdef DEBUG" for dbg_port_buf() > to "#if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)" > is probably not acceptable due to the overhead of dbg_port_buf()?
I don't understand your question. Doesn't dbg_port_buf need to be defined whenever dynamic debugging is enabled?
Alternatively, the definition of dbg_port_buf (and related routines) in the !defined(DEBUG) case could be changed; you could add
buf[0] = 0;
That way you wouldn't get garbage out, although you wouldn't get anything useful either.
Alan Stern
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