于 2014/2/27 10:53, xiakaixu 写道: > Hi Namhyung, > > 于 2014/2/26 16:03, Namhyung Kim 写道: >> Hi xiakaixu, >> >>> 于 2014/2/19 9:48, xiakaixu 写道: >>>> Hi all, >>>> >>>> There is a bug found in my work when running "perf record". The basic >>>> information >>>> is here. As we know, perf record is a parent process and the programme >>>> traced is >>>> a child process when running "perf record". Sometimes the child process >>>> become >>>> zombie state and disappear until the parent process is killed. The bug >>>> stays in linux/ >>>> tools/perf/builtin-record.c. >>>> ********************************************************************* >>>> static int __cmd_record(struct perf_record *rec, int argc, const char >>>> **argv) >>>> ...... >>>> if (hits == rec->samples) { >>>> if (done) >>>> break; >>>> err = poll(evsel_list->pollfd, >>>> evsel_list->nr_fds, -1); >>>> waking++; >>>> } >>>> ...... >>>> ********************************************************************* >>>> The parent process still call the function >>>> poll(evsel_list->pollfd, evsel_list->nr_fds, -1) when the child process >>>> has exited >>>> already, which caused a zombie process. >>>> >>>> May I have your opinion ? >>>> Waiting for your reply! >> >> Do you have a real bug report based on this?
> yeah, of course we have it, I'll be glad to provide it if necessary. >> >> AFAIK perf record installed a signal handler for SIGCHLD so it'll set >> the 'done' variable when child exits and then break the loop. > yes, you are right. Though the 'done' varible will be set when child exits, > there is time gap between "if(done)" statement and "poll(...)" function. > The 'done' variable won't be judge when child exits in this time gap. > You know this time gap is instruction level, so this bug is small probability. > My solution is adding a while(...) statement outside poll(...) function. >> >> Thanks, >> Namhyung >> . >> > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/