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[12:41] <darius12_> hi, upstart's testsuite hangs in nih_child_poll() (with signal from traced child) |
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[12:42] <darius12_> I left it for ~ 15 minutes before I killed it |
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[12:42] <ion_> keybuk: Btw, did you notice this? |
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[12:42] <ion_> 2008-01-25 17:02:41 < ion_> keybuk: An idea occured to me: how about disallowing nih_ref when the object has a parent (so that it always has a reference count of 1 and nih_unref would be used just like nih_free is now – not callect directly on the object), thus reference counting could *optionally* be used with parentless objects? |
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[12:42] <ion_> 2008-01-25 17:03:54 < ion_> Children would be released whenever their parent is released, and the refcounting may be used with the parent when appropriate just by using nih_ref. |
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[12:46] <Keybuk> darius12_: kernel version? |
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[12:46] <Keybuk> ion_: that wouldn't seem unreasonable |
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[12:46] <Keybuk> ion_: would that let you do what you want? |
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[12:46] <darius12_> 2.6.18 from debian etch |
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[12:46] <ion_> keybuk: Yes |
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[12:46] <darius12_> I suspected the kernel as well |
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[12:47] <Keybuk> darius12_: you need a newer kernel (assuming you're talking about trunk's test suite) |
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[12:47] <darius12_> so I 've been building 2.6.24 to try with this too |
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[12:47] <darius12_> ah, thanks :-) |
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[12:47] <Keybuk> the test suite manages to find a couple of kernel bugs ;) |
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[12:47] <Keybuk> in fact, that particular one it's hanging on, got a CVE assigned to it |
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[12:48] <darius12_> yes, I 'm talking about trunk's latest testsuite, I noticed you mentioning about the usefulness of upstart as a kernel bug uncovering tool :-) |
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[12:50] <Keybuk> the test suite uses waitid(W_NOWAIT) so it can ensure that there's no race conditions |
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[12:50] <Keybuk> ie. if it kills a child, it waits without reaping for the child to die, so then when it calls nih_child_poll() it knows *that* function's call to wait() will work |
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[12:51] <Keybuk> it turns out that waitid(W_NOWAIT) isn't used much, so had some issues |
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[12:51] <Keybuk> especially when combined with ptrace |
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[12:51] <darius12_> I see |
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[12:52] <darius12_> I 'm a bit scared about upstart using ptrace |
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[12:53] <darius12_> Especially if there is a bit of flux in this area when/if utrace gets merged |
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[12:53] <darius12_> I 'm ok with strace breaking for a while but pid #1 is a different story ... |
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[12:56] <darius12_> Then again, if upstart manages to get in fedora it will get testing combined with utrace so bugs will probably get fixed before utrace becomes mainstream |
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[12:59] <Keybuk> I haven't heard of utrace before |
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[12:59] <darius12_> It is roland mcgrath's heroic effort to reimplement ptrace in the kernel |
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[13:00] <darius12_> (the kernel-userspace interface of course stays the same) |
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[13:01] <darius12_> It is quite nice, e.g., with it you can implement policies such as "on segfault, just freeze the thread and wait for me to attach a debugger instead of dumping core" |
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[13:02] <darius12_> very easily in few lines of code |
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[13:02] <ion_> Neat |
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[13:03] <darius12_> and it gets even neater when you want to implement dtrace-like monitoring etc |
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[13:03] <darius12_> It is already in the fedora kernel and it is slowly getting merged upstream |
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[13:16] <Keybuk> if the interface is the same, there shouldn't be any problems there? |
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[13:20] <darius12_> just increased probability for new bugs :-) |
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[13:20] <darius12_> ptrace is pretty hard to get right |
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[13:22] <Keybuk> reimplementations always do |
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[13:22] <Keybuk> happily we have a test suite ;) |
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[13:24] <darius12_> The test suite will give you reassurance that the bug is not yours. |
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[13:25] <Keybuk> it also helps us fix the kernel bug too |
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[13:25] <Keybuk> since it's a small (10-20 lines of code) test case for the bug |
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[13:25] <darius12_> yep, this is also true :-) |
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[13:27] <darius12_> maybe upstart's testsuite should be added to test.kernel.org |
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[13:33] <Keybuk> :-) |
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[13:45] <darius12_> Is there a way to declare in upstart that bash wants to be killed with SIGHUP? |
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[13:48] <Keybuk> it does? |
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[13:48] <Keybuk> (not yet) |
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[13:48] <darius12_> yes, otherwise it doesn't save its history |
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[13:48] <darius12_> which is very annoying |
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[13:50] <Keybuk> you spawn a login shell with Upstart? :) |
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[13:51] <Keybuk> don't you usually spawn getty or login for that? |
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[13:51] <darius12_> yes, but how about kde konsole sessions? |
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[13:52] <darius12_> bbiaw |
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[13:54] <Keybuk> those get killed by other means |
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[13:54] <Keybuk> Upstart doesn't send them a signal directly since it doesn't know about them |
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[13:55] <Keybuk> they might be in a process group of something that Upstart does know about |
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[13:55] <Keybuk> or they might get the signal from something else that is being killed itself |
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[15:01] <darius12_> back |
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[15:02] <darius12_> you are right. Login sends sighup to its child login shell when it gets a sigterm |
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[15:02] <darius12_> This didn't happen when I was testing it ages ago (it seems it has been fixed since 2003) |
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[15:03] <darius12_> So there is no problem |
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[15:04] <darius12_> for kde I guess when it doesn't work, konsole is to blame |
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=== kyle__ is now known as kylem |
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[17:02] <darius12_> Keybuk: with kernel 2.6.24 I get 3 testsuite failures: |
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[17:03] <darius12_> nih_dir_walk() nih_main_write_pidfile() and nih_watch_new() |
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[17:04] <Keybuk> which failures? |
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[17:05] <darius12_> http://pastebin.ca/895177 |
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[17:17] <Keybuk> err, ok |
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[17:17] <Keybuk> how kooky |
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[17:20] <Keybuk> things that should fail are not failing |
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[17:39] <darius12_> which kernel version are you testing upstart with? |
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[17:40] <Keybuk> ubuntu hardy stock |
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[17:41] <darius12_> it looks like it is 2.6.24-rc8 based |
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[17:41] <darius12_> strange |
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