On Tuesday 29 April 2014 18:29, Bryan Evenson wrote: > > -----Original Message----- > > From: Denys Vlasenko [mailto:vda.li...@googlemail.com] > > Sent: Tuesday, April 29, 2014 10:19 AM > > To: Bryan Evenson > > Cc: busybox; gri...@gmx.de > > Subject: Re: [PATCH 1/1] hwclock: Verify RTC file descriptor; use reentrant > > functions > > > > On Fri, Apr 25, 2014 at 7:48 PM, Bryan Evenson > > <beven...@melinkcorp.com> wrote: > > > If the RTC is in use by another process or if the dev interface is not > > > properly established, calling rtc_xopen will fail. > > > > I don't see how is that possible: > > > > int FAST_FUNC rtc_xopen(const char **default_rtc, int flags) { > > int rtc; > > > > if (!*default_rtc) { > > *default_rtc = "/dev/rtc"; > > rtc = open(*default_rtc, flags); > > if (rtc >= 0) > > return rtc; > > *default_rtc = "/dev/rtc0"; > > rtc = open(*default_rtc, flags); > > if (rtc >= 0) > > return rtc; > > *default_rtc = "/dev/misc/rtc"; > > } > > > > return xopen(*default_rtc, flags); } > > > > If all open()'s fail, we end up executing "return xopen(...)". > > And xopen() never returns failure - it exits with error message instead. > > Sorry, a little clarification on what I am seeing. If rtc_xopen can't open > the rtc it returns an error instead of the file descriptor for the rtc.
I don't see how this can happen. Do you have evidence rtc_xopen() did return a result less than zero? > > > The problem can be reproduced by running two instances of the > > > following shell script: > > > > > > #!/bin/sh > > > while [ 1 ]; do > > > /sbin/hwclock -w -u > > > sleep 1; > > > done > > > > Works for me with no problems with current bbox git tree. > > Modifying it to run hwclock much more often: > > > > #!/bin/sh > > i=0 > > while true; do > > ./busybox hwclock -w -u > > echo $i $? > > : $((i++)) > > done > > > > and running two instances, I get this: > > > > ... > > ... > > 11461 0 > > hwclock: can't open '/dev/misc/rtc': No such file or directory > > 11462 1 > > 11463 0 > > hwclock: can't open '/dev/misc/rtc': No such file or directory > > 11464 1 > > hwclock: can't open '/dev/misc/rtc': No such file or directory > > 11465 1 > > 11466 0 > > ... > > ... > > > > Looks like it doesn't hang. > > It's a question whether it should be failing or retrying, but I don't see it > > hanging. > > > > Maybe. The incrementing number is sequential, indicating it is from a single > instance of the script. I ran two instances of the script *in two different terminals*. Both are showing the output similar to what I posted: periodically, hwclock fails. > Of course this was just a few lines of output, so both scripts could be > running on your system without problem and there just wasn't enough data to > show it. > Could you confirm that your output shows both scripts are still running? Yes, I had two scripts running in parallel. No, the output doesn't show both of them at once - the output is from one of the two concurrently running scripts. -- vda _______________________________________________ busybox mailing list busybox@busybox.net http://lists.busybox.net/mailman/listinfo/busybox
