RFR (M): JDK-8200298 Unify all unix versions of libjsig/jsig.c
Magnus Ihse Bursie
magnus.ihse.bursie at oracle.com
Thu Apr 5 11:07:54 UTC 2018
On 2018-04-05 12:30, David Holmes wrote:
> On 5/04/2018 7:52 PM, Magnus Ihse Bursie wrote:
>> On 2018-04-05 10:30, David Holmes wrote:
>>> On 5/04/2018 6:07 PM, Magnus Ihse Bursie wrote:
>>>>
>>>>
>>>> On 2018-04-04 09:59, David Holmes wrote:
>>>>> Hi Magnus,
>>>>>
>>>>> Sorry for the delay ...
>>>>>
>>>>> On 28/03/2018 8:15 PM, Magnus Ihse Bursie wrote:
>>>>>>
>>>>>> On 2018-03-27 18:24, Thomas Stüfe wrote:
>>>>>>> Hi Magnus,
>>>>>>>
>>>>>>> just a cursory look, will look in greater detail tomorrow.
>>>>>>>
>>>>>>> This is good, thanks for doing this.
>>>>>>>
>>>>>>> As I wrote offlist, please remove the painfully wrong AIX
>>>>>>> "workarounds". I do not know why we did this - the original code
>>>>>>> is quite old - my assumption is that dlsym(RTLD_NEXT) was not
>>>>>>> working as expected on older AIX versions. Well, it should work
>>>>>>> now according to IBMs manpages. Will test later.
>>>>>> Ok.
>>>>>>>
>>>>>>> __thread is not Posix. I would prefer pthread_get/set_specific
>>>>>>> instead, which is more portable.
>>>>>>
>>>>>> I have surrounded this code with #ifdef MACOSX now.
>>>>>>
>>>>>> Here is an updated webrev. It includes the changes requested by
>>>>>> you and David:
>>>>>>
>>>>>> * No more AIX workarounds
>>>>>> * Solaris use pthreads
>>>>>> * The "reentry" code is #ifdef MACOSX.
>>>>>
>>>>> That all seems good.
>>>> Good. :)
>>>>
>>>>>
>>>>>> I also assumed that NSIG is available and working on Solaris.
>>>>>> I'll let David decide if he is happy with that. The alternative
>>>>>> is to go back to the Solaris-specific code that allocates sact on
>>>>>> the heap.
>>>>>
>>>>> Unfortunately NSIG is a problem on Solaris:
>>>>>
>>>>> http://austingroupbugs.net/view.php?id=741
>>>>>
>>>>> It's use also precludes the use of the real-time signals - which
>>>>> limits Linux as well. But I'm not completely clear on exactly how
>>>>> signals may be numbered in their entirety so I wouldn't
>>>>> necessarily suggest trying to use SIGRTMAX+1 as the number of
>>>>> available signals, other than on Solaris.
>>>> Ok. I hope I understand you correctly. I have replaced NSIG with
>>>> MAX_SIGNALS, which is defined as NSIG on all platforms except
>>>> Solaris, where it is defined as SIGRTMAX+1.
>>>>
>>>> Updated webrev:
>>>> http://cr.openjdk.java.net/~ihse/JDK-8200298-unify-libjsig/webrev.08
>>>>
>>>> (8th time's a charm..?)
>>>
>>> Nope - you can't use SIGRTMAX+1 to allocate a static array as it is
>>> not a constant expression. That's why Solaris uses malloc.
>>
>> Duh. Right.
>>
>> Oooookay. Like this, then?
>>
>> http://cr.openjdk.java.net/~ihse/JDK-8200298-unify-libjsig/webrev.09
>>
>> I have restored the calls to allocate_sact() in the same locations as
>> in the original solaris version. Hopefully, those are correct. :-)
>
> Yes you have restored them in the same locations.
>
> As for correctness ... there are some preexisting issues I spotted. Do
> you really want to know? ;-) Well only one correctness issue, plus one
> unnecessary code issue:
Will it ever end?! :-)
>
> Correctness:
>
> 83 #ifdef SOLARIS
> 84 if (sact == NULL) {
> 85 sact = (struct sigaction *)malloc((MAX_SIGNALS) *
> (size_t)sizeof(struct sigaction));
> 86 memset(sact, 0, (MAX_SIGNALS) * (size_t)sizeof(struct
> sigaction));
> 87 }
> 88
> 89 if (sact == NULL) {
> 90 printf("%s\n", "libjsig.so unable to allocate memory");
> 91 exit(0);
> 92 }
>
> The NULL check at line 89 needs to move to line 86 before we do memset
> on a NULL pointer.
>
> Redundant code:
>
> 142 static void save_signal_handler(int sig, sa_handler_t disp, bool
> is_sigset) {
> 143 sigset_t set;
> 144
> 145 allocate_sact();
>
> There are two calls to save_signal_handler, both preceded by a call to
> allocate_sact(), so we don't need to do it again at line 145.
Ok, I'll fix it while I'm at it.
New webrev:
http://cr.openjdk.java.net/~ihse/JDK-8200298-unify-libjsig/webrev.10
Also, here is a webrev with the same patch applied to jdk/hs. (I have
also included the needed changes to how libjsig is compiled, which are
pushed to jdk/jdk but not yet integrated into jdk/hs). The patch file
from this webrev can be applied to jdk/hs, so Thomas hopefully can test
the AIX changes.
Let's hope this is the final iteration...
/Magnus
>
> Thanks,
> David
>
>> /Magnus
>>>
>>> David
>>>
>>>
>>>> /Magnus
>>>>
>>>>>
>>>>> Thanks,
>>>>> David
>>>>>
>>>>>> Webrev:
>>>>>> http://cr.openjdk.java.net/~ihse/JDK-8200298-unify-libjsig/webrev.05
>>>>>>
>>>>>> Once again, here is also a webrev that shows the difference
>>>>>> between the original files and the new, unified file. Even if
>>>>>> it's hard to read, it shows what the effects will be for each
>>>>>> platform.
>>>>>>
>>>>>> Webrev:
>>>>>> http://cr.openjdk.java.net/~ihse/JDK-8200298-unify-libjsig/webrev.04/
>>>>>>
>>>>>>
>>>>>> /Magnus
>>>>>>
>>>>>>>
>>>>>>> Thanks!
>>>>>>>
>>>>>>> Thomas
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Tue, Mar 27, 2018 at 11:42 AM, Magnus Ihse Bursie
>>>>>>> <magnus.ihse.bursie at oracle.com
>>>>>>> <mailto:magnus.ihse.bursie at oracle.com>> wrote:
>>>>>>>
>>>>>>> When I was about to update jsig.c, I noticed that the four
>>>>>>> copies
>>>>>>> for aix, linux, macosx and solaris were basically the same,
>>>>>>> with
>>>>>>> only small differences. Some of the differences were not
>>>>>>> even well
>>>>>>> motivated, but were likely the result of this code duplication
>>>>>>> causing the code to diverge.
>>>>>>>
>>>>>>> A better solution is to unify them all into a single unix
>>>>>>> version,
>>>>>>> with the few platform-specific changes handled on a
>>>>>>> per-platform
>>>>>>> basis.
>>>>>>>
>>>>>>> I've made the following notable changes:
>>>>>>>
>>>>>>> * I have removed the version check for Solaris. All other
>>>>>>> platforms seem to do fine without it, and in general, we don't
>>>>>>> mistrust other JDK libraries. An alternative is to add this
>>>>>>> version check to all other platforms instead. If you think
>>>>>>> this is
>>>>>>> the correct course of action, let me know and I'll fix it.
>>>>>>>
>>>>>>> * Solaris used to have a dynamically allocated sact, instead
>>>>>>> of a
>>>>>>> statically allocated array as all other platforms have. It's
>>>>>>> not
>>>>>>> likely to be large, and the size is known at compile time, so
>>>>>>> there seems to be no good reason for this.
>>>>>>>
>>>>>>> * Linux and macosx used a uint32_t/uint64_t instead of sigset_t
>>>>>>> for jvmsigs, as aix and solaris do. This is a less robust
>>>>>>> solution, and the added checks show that it has failed in the
>>>>>>> past. Now all platforms use sigset_t/sigismember().
>>>>>>>
>>>>>>> Also worth noting:
>>>>>>>
>>>>>>> * Solaris is not using pthreads, but it's own thread library,
>>>>>>> which accounts for most of the #ifdef SOLARIS.
>>>>>>>
>>>>>>> * In general, if an implementation was needed on one
>>>>>>> platform, but
>>>>>>> has no effect or is harmless on others, I've kept it on all
>>>>>>> platforms instead of sprinkling the code with #ifdefs.
>>>>>>>
>>>>>>> To facilitate code review, here is a specially crafted
>>>>>>> webrev that
>>>>>>> shows the differences compared to each of the individual,
>>>>>>> original
>>>>>>> per-OS versions of jsig.c:
>>>>>>> http://cr.openjdk.java.net/~ihse/JDK-8200298-unify-libjsig/webrev.01
>>>>>>>
>>>>>>> <http://cr.openjdk.java.net/%7Eihse/JDK-8200298-unify-libjsig/webrev.01>
>>>>>>>
>>>>>>>
>>>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8200298
>>>>>>> <https://bugs.openjdk.java.net/browse/JDK-8200298>
>>>>>>> WebRev:
>>>>>>> http://cr.openjdk.java.net/~ihse/JDK-8200298-unify-libjsig/webrev.03
>>>>>>>
>>>>>>> <http://cr.openjdk.java.net/%7Eihse/JDK-8200298-unify-libjsig/webrev.03>
>>>>>>>
>>>>>>>
>>>>>>> /Magnus
>>>>>>>
>>>>>>>
>>>>>>
>>>>
>>
More information about the build-dev
mailing list