[PATCH] 8170639: [Linux] jsig is limited to a maximum of 64 signals
David Holmes
david.holmes at oracle.com
Tue Mar 5 02:45:01 UTC 2019
On 5/03/2019 12:22 pm, Ao Qi wrote:
>
>
> David Holmes <david.holmes at oracle.com <mailto:david.holmes at oracle.com>>
> 于2019年3月1日 周五下午12:18写道：
>
> Hi,
>
> On 28/02/2019 9:01 pm, Ao Qi wrote:
> > Hi,
> >
> > This version is more consolidated than my first version in this
> > thread: http://cr.openjdk.java.net/~aoqi/8170639/webrev.01/. I filed
> > my first version here:
> > http://cr.openjdk.java.net/~aoqi/8170639/webrev.00/
> >
> > I fixed the linux and bsd using sigset_t, so jsig is not limited to a
> > maximum of 64 signals for linux and bsd. The logic of aix and solaris
> > is not changed.
>
> Thanks for doing this. Overall this is a much better approach.
>
> I have two requests.
>
> There are too many ifdefs for solaris in the os_posix.cpp code. I
> hadn't
> realized the difference between Solaris and the other *NIX platforms in
> this area (allowing for real-time signal chaining). Please restore the
> Solaris code and put one ifndef solaris around the new code is
> os_posix.[ch]pp.
>
>
> Hi David,
>
> Thanks for your review and advice.
>
> I think the best way is to eliminate ifdefs for solaris, but as you said
> in a previous email [1]: "SIGRTMAX is a macro not a constant so you
> can't declare a static array using it. You would need to malloc the
> array as done on Solaris." So I have to use ifdefs for solaris, I did
> not find a way to eliminate it. I have used one ifndef solaris as you
> request.
What I was suggesting was to leave os_solaris.cpp alone completely for
this change, and have the new os_posix.* functions defined in an
"#ifndef SOLARIS" block.
Thanks,
David
PS. I will be away for a few days after today.
> There's no need for a separate os::posix::init_sigs() API, just do the
> signal set initialization in os::posix::init_2();
>
>
> I have done it.
>
> Webrev: http://cr.openjdk.java.net/~aoqi/8170639/webrev.02/
>
> Tested:
> build tests
> linux-x86_64-minimal-fastdebug
> linux-x86_64-zero-fastdebug
> linux-x86_64-server-fastdebug
> linux-x86_64-minimal-release
> linux-x86_64-zero-release
> linux-x86_64-server-release
> solaris-x86_64-server-release
> solaris-x86_64-server-fastdebug
> linux-mips64el-zero-release
> linux-mips64el-zero-fastdebug
>
> jtreg tests
> linux-x86_64-server-release: tier1,
> hotspot-tier1(JAVA_OPTIONS=-XX:-UseSignalChaining),
> hotspot-tier1(JAVA_OPTIONS=-XX:+AllowUserSignalHandlers)
> solaris-x86_64-server-release: hotspot-tier1,
> hotspot-tier1(JAVA_OPTIONS=-XX:-UseSignalChaining)
>
> Thanks,
> Ao Qi
>
> [1]
> https://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2018-March/027219.html
>
>
> Thanks,
> David
> -----
>
> > The tests I did:
> >
> > build tests：
> > linux-x86_64-server-release
> > linux-x86_64-server-fastdebug
> > linux-x86_64-zero-release
> > linux-x86_64-zero-fastdebug
> > linux-x86_64-minimal-release
> > linux-x86_64-minimal-fastdebug
> > solaris-x86_64-server-release
> > solaris-x86_64-server-fastdebug
> > linux-mips64el-zero-release
> > linux-mips64el-zero-fastdebug
> >
> > jtreg tests：
> > linux-x86_64-server-release: tier1, tier2, tier3
> > linux-x86_64-server-fastdebug: tier1
> > solaris-x86_64-server-release: hotspot-tier1
> >
> > No regression was found. Could you please review this version?
> >
> > On Fri, Jan 25, 2019 at 10:56 PM Magnus Ihse Bursie
> > <magnus.ihse.bursie at oracle.com
> <mailto:magnus.ihse.bursie at oracle.com>> wrote:
> >>
> >> On 2018-12-18 01:33, David Holmes wrote:
> >>> On 18/12/2018 9:57 am, Ao Qi wrote:
> >>>> Hi,
> >>>>
> >>>> On Tue, Dec 18, 2018 at 4:32 AM David Holmes
> >>>> <david.holmes at oracle.com <mailto:david.holmes at oracle.com>> wrote:
> >>>>>
> >>>>> On 17/12/2018 9:48 pm, Ao Qi wrote:
> >>>>>> Hi David Holmes,
> >>>>>>
> >>>>>> Thanks for your reply. It makes sense. Is it possible to create
> >>>>>> another bug ID to fix the problem?
> >>>>>
> >>>>> I'd prefer to see this fixed properly than point fixed on
> linux for an
> >>>>> unsupported platform.
> >>>>
> >>>> I thought the problem is "[Linux] jsig is limited to a maximum
> of 64
> >>>> signals" and the patch was intended to fixed this problem. It just
> >>>> didn't use "A better solution", but I think it is better than the
> >>>> current situation.
> >>>
> >>> Better for you but I would prefer to see an overall better
> solution.
> >>> It really shouldn't be very difficult. Compare the AIX version with
> >>> your improved Linux version, reconcile any differences, and
> make it a
> >>> shared posix version, then confirm it works on OS X and Solaris.
> >>>
> >>>> Is zero/mips (or all platforms having more than 64 signals) a
> >>>> unsupported platform?
> >>>
> >>> Yes. We make allowances for Zero as it can support a vast range of
> >>> platforms for which no native OpenJDK port exists (in the case
> of MIPS
> >>> that port seems inactive), but in general we don't go out of
> our way
> >>> to make changes in the main code that only benefit such platforms.
> >>>
> >>> I'm subtly trying to coerce you into making the change I'd like
> to see
> >>> here. ;-) I can assist with build/test on other POSIX platforms.
> >> If you are going down that route, I recommend looking at
> >> src/java.base/unix/native/libjsig/jsig.c for inspiration. It was
> >> recently unified across all unix platforms we currently support,
> so any
> >> special treatment there for a specific platform (I think
> solaris, macosx
> >> and aix have some special stuff going on), is likely to apply to the
> >> signal handling inside the VM as well. On the other hand, general
> >> solutions that worked in jsig.c is likely to work as well in the VM.
> >>
> >
> > Hi Magnus,
> >
> > Thanks for you information and advise. That is very helpful.
> > Difference between hotspot/os/${os_name}/os_${os_name}.cpp is much
> > more than the difference between ${os_name}/native/libjsig/jsig.c, so
> > it is difficult to unify all the jsig related codes into os_posix.hpp
> > and os_posix.cpp. Maybe I would try to do it in another issue.
> >
> > Cheers,
> > Ao Qi
> >
> >> /Magnus
> >>>
> >>> Cheers,
> >>> David
> >>>
> >>>> Cheers,
> >>>> Ao Qi
> >>>>>
> >>>>> Thanks,
> >>>>> David
> >>>>>
> >>>>>> Cheers,
> >>>>>> Ao Qi
> >>>>>>
> >>>>>> On Mon, Dec 17, 2018 at 7:30 PM David Holmes
> >>>>>> <david.holmes at oracle.com <mailto:david.holmes at oracle.com>>
> wrote:
> >>>>>>>
> >>>>>>> Thanks for reminding me about the rest of the discussion. The
> >>>>>>> point of
> >>>>>>> the RFE I filed was to examine if we could get a
> consolidated POSIX
> >>>>>>> version using sigset_t. I'd rather see that than a point
> fix for
> >>>>>>> Linux.
> >>>>>>>
> >>>>>>> Thanks,
> >>>>>>> David
> >>>>>>>
> >>>>>>> On 17/12/2018 6:50 pm, Ao Qi wrote:
> >>>>>>>> Hi David Holmes,
> >>>>>>>>
> >>>>>>>> I am not sure what is the specific issue of "NSIG not being
> >>>>>>>> defined".
> >>>>>>>> Do you mean the issue mentioned in "but I found that NSIG was
> >>>>>>>> missing
> >>>>>>>> from signal.h on some architectures, mips being among
> them"[1]? If
> >>>>>>>> yes, James Cowgill answered this in [2]. I check it on
> MIPS, NSIG is
> >>>>>>>> defined in signal.h and it is 128.
> >>>>>>>>
> >>>>>>>> Cheers,
> >>>>>>>> Ao Qi
> >>>>>>>>
> >>>>>>>> [1]
> >>>>>>>>
> http://mail.openjdk.java.net/pipermail/hotspot-dev/2016-November/025401.html
> >>>>>>>> [2]
> >>>>>>>>
> http://mail.openjdk.java.net/pipermail/hotspot-dev/2016-December/025416.html
> >>>>>>>>
> >>>>>>>> On Mon, Dec 17, 2018 at 8:02 AM David Holmes
> >>>>>>>> <david.holmes at oracle.com <mailto:david.holmes at oracle.com>>
> wrote:
> >>>>>>>>>
> >>>>>>>>> Hi,
> >>>>>>>>>
> >>>>>>>>> Was the issue of NSIG not being defined resolved?
> >>>>>>>>>
> >>>>>>>>> Thanks,
> >>>>>>>>> David
> >>>>>>>>>
> >>>>>>>>> On 14/12/2018 10:23 pm, Ao Qi wrote:
> >>>>>>>>>> Hi all,
> >>>>>>>>>>
> >>>>>>>>>> Zero does not build on Linux MIPS (actually all Linux of
> NSIG >
> >>>>>>>>>> 64)
> >>>>>>>>>> since OpenJDK 9, because NISG is 128 on MIPS and can not be
> >>>>>>>>>> encoded in
> >>>>>>>>>> uint64_t sigs. James Cowgill from Debian tried to push a
> patch
> >>>>>>>>>> fixing
> >>>>>>>>>> this[1] but it seems he failed. I would like to try again to
> >>>>>>>>>> request
> >>>>>>>>>> fixing this in http://hg.openjdk.java.net/jdk/jdk. This was
> >>>>>>>>>> fixed in
> >>>>>>>>>> AIX implementation.
> >>>>>>>>>>
> >>>>>>>>>> After applying this patch, zero can be built on MIPS (Debian
> >>>>>>>>>> testing).
> >>>>>>>>>> I've run the jtreg tests [2] on x86 Linux.
> >>>>>>>>>>
> >>>>>>>>>> [1]
> >>>>>>>>>>
> http://mail.openjdk.java.net/pipermail/hotspot-dev/2016-November/025399.html
> >>>>>>>>>> [2]
> >>>>>>>>>>
> https://download.java.net/openjdk/testresults/12/docs/howtoruntests.html
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> Cheers,
> >>>>>>>>>> Ao Qi
> >>>>>>>>>>
> >>>>>>>>>> $ hg export -r 52869
> >>>>>>>>>> # HG changeset patch
> >>>>>>>>>> # User aoqi
> >>>>>>>>>> # Date 1544089853 0
> >>>>>>>>>> # Thu Dec 06 09:50:53 2018 +0000
> >>>>>>>>>> # Node ID 3eea22b79dc3a4bf26616bde1acb587e3f56e6fe
> >>>>>>>>>> # Parent b4982a22926b4ddf1a7b1f770e4d42ce8c1dd575
> >>>>>>>>>> 8170639: [Linux] jsig is limited to a maximum of 64 signals
> >>>>>>>>>>
> >>>>>>>>>> diff -r b4982a22926b -r 3eea22b79dc3
> >>>>>>>>>> src/hotspot/os/linux/os_linux.cpp
> >>>>>>>>>> --- a/src/hotspot/os/linux/os_linux.cpp Thu Dec 06 11:54:39
> >>>>>>>>>> 2018 +0530
> >>>>>>>>>> +++ b/src/hotspot/os/linux/os_linux.cpp Thu Dec 06 09:50:53
> >>>>>>>>>> 2018 +0000
> >>>>>>>>>> @@ -4434,10 +4434,7 @@
> >>>>>>>>>>
> >>>>>>>>>> // For signal-chaining
> >>>>>>>>>> struct sigaction sigact[NSIG];
> >>>>>>>>>> -uint64_t sigs = 0;
> >>>>>>>>>> -#if (64 < NSIG-1)
> >>>>>>>>>> -#error "Not all signals can be encoded in sigs. Adapt
> its type!"
> >>>>>>>>>> -#endif
> >>>>>>>>>> +sigset_t sigs;
> >>>>>>>>>> bool os::Linux::libjsig_is_loaded = false;
> >>>>>>>>>> typedef struct sigaction *(*get_signal_t)(int);
> >>>>>>>>>> get_signal_t os::Linux::get_signal_action = NULL;
> >>>>>>>>>> @@ -4516,7 +4513,7 @@
> >>>>>>>>>> }
> >>>>>>>>>>
> >>>>>>>>>> struct sigaction*
> os::Linux::get_preinstalled_handler(int
> >>>>>>>>>> sig) {
> >>>>>>>>>> - if ((((uint64_t)1 << (sig-1)) & sigs) != 0) {
> >>>>>>>>>> + if (sigismember(&sigs, sig)) {
> >>>>>>>>>> return &sigact[sig];
> >>>>>>>>>> }
> >>>>>>>>>> return NULL;
> >>>>>>>>>> @@ -4525,7 +4522,7 @@
> >>>>>>>>>> void os::Linux::save_preinstalled_handler(int sig,
> struct
> >>>>>>>>>> sigaction& oldAct) {
> >>>>>>>>>> assert(sig > 0 && sig < NSIG, "vm signal out of
> expected
> >>>>>>>>>> range");
> >>>>>>>>>> sigact[sig] = oldAct;
> >>>>>>>>>> - sigs |= (uint64_t)1 << (sig-1);
> >>>>>>>>>> + sigaddset(&sigs, sig);
> >>>>>>>>>> }
> >>>>>>>>>>
> >>>>>>>>>> // for diagnostic
> >>>>>>>>>> @@ -4616,6 +4613,7 @@
> >>>>>>>>>> (*begin_signal_setting)();
> >>>>>>>>>> }
> >>>>>>>>>>
> >>>>>>>>>> + ::sigemptyset(&sigs);
> >>>>>>>>>> set_signal_handler(SIGSEGV, true);
> >>>>>>>>>> set_signal_handler(SIGPIPE, true);
> >>>>>>>>>> set_signal_handler(SIGBUS, true);
> >>>>>>>>>>
> >>
>
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