Defect in XSH 2.9.5 Thread Cancelation

[yyyyyyyy@xxxxxxxxxx]

        Defect report from : Alexander Terekhov , IBM

(Please direct followup comments direct to yyyyyyyyyyyyyy@xxxxxxxxxxxxx)

@ page 54-57 line 2226-2358 section 2.9.5 Thread Cancelation comment {6}

Problem:

Defect code :  3. Clarification required


http://groups.google.com/groups?selm=GcRH7.1479%24RL6.47817%40news.cpqcorp.net

David Butenhof (yyyyyyyyyyyyyy@xxxxxxxxxx) wrote:

"....
 This discussion HAS pointed out a legitimate "gotcha" in the standard; 
 there's really nothing you can do to deal with cancellation points in a 
 signal handler. We've always said, however, that "signals and threads don't 
 mix well". This is another example, and there's no good solution.

 Alexander Terekhov suggested making cancellation points ignore a pending 
 cancel within a "signal catching function". While that's not entirely a BAD 
 idea, it's not that simple. For one thing, most UNIX kernels don't really 
 keep track of whether you're in a "signal catching function". The only 
 state that distinguishes "a signal catching function" is that there's some 
 sort of a signal trampoline frame on the stack, and there MAY be a signal 
 "temporarily" blocked by delivery of a signal. It'd be difficult to make 
 the standard specify behavior based on this nebulous "state"; not only are 
 there technical complications, but I suspect that gaining any sort of 
 political concensus would be really difficult. 
 ...."


Action:

Please advise.