RFR(XS): 8212883: Setting a double manageable flag with jcmd/jinfo crashes the JVM (original) (raw)

Thomas Stüfe thomas.stuefe at gmail.com
Wed Oct 24 06:32:49 UTC 2018


Hi,

I am really not sure about the implicit boolean comparison of the sscanf return value (not only for this but the other flag variants too).

sscanf may return 0-n (for 0-n matched items) and EOF in case of an error. Is EOF always 0? Otherwise, to be sure, I would compare the return value with 1 since we expect 1 item to match.

Just my 5c.

Cheers, Thomas

On Wed, Oct 24, 2018 at 1:16 AM David Holmes <david.holmes at oracle.com> wrote:

Hi Tony, On 24/10/2018 8:13 AM, Tony Printezis wrote: > Webrev here: > > http://cr.openjdk.java.net/~tonyp/8212883/webrev.0/ > > Currently, HotSpot doesn’t actually have any double manageable flags, which > is why I think no-one has hit this before. I recently added a couple to our > own builds and I noticed that setting them is not handled correctly in the VM. > The fix is pretty trivial (mostly cut-and-paste from what the code does for > the other types). I agree the fix is pretty obvious and straight-forward. > I tested it by introducing a dummy double manageable flag and I can set it > with jinfo/jcmd and jconsole (these cover all the various paths in the > changes). Is it worth expanding the > serviceability/attach/AttachSetGetFlag.java test to also get/set a double > flag (I’d need to introduce a dummy double manageable flag to do that > though)? I hate to see new code untested ... but then it seems we don't have tests for all the existing types of flags anyway. Reviewed. Thanks, David > Regards, > > Tony > > > ————— > Tony Printezis | @TonyPrintezis | tprintezis at twitter.com >



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