Request for code review (smallest review ever)

Keith McGuigan keith.mcguigan at
Wed Feb 15 03:33:01 PST 2012

On 2/15/2012 2:34 AM, David Holmes wrote:
> On 15/02/2012 7:20 AM, keith mcguigan wrote:
>> Well, ok, I guess it's not the smallest code change -- I think I've
>> matched this before -- but I guarantee you won't see one smaller than
>> this!
>> It's a one-liner (a one-character-er) to accept 0 as a successful return
>> from an ioctl() call, for registering dtrace providers.
> Have to ask - why have we not noticed this before? No test coverage?

Not really sure.  I suspect testing missed this somehow, but there are 
scenarios where this would work fine.

Basically, this would fail only when the JSDT provider was the very 
first dtrace provider registered with the system for the current 
process.  In the past, the JVM probes were registered automatically at 
load time, so any JSDT providers were not "first".  When the JVM probes 
were switched to lazy loading (a relatively recent change), this opened 
the door for this error.  Similarly, if any loaded library loaded probes 
before trying to create the JSDT provider, that would also mask this 
bug.  So it's possible that this was somehow hidden from our testing 

- Keith

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