On 02/18/2013 04:10 PM, Daniel Lezcano wrote: > On 02/18/2013 09:46 PM, Stéphane Graber wrote: >> On 02/18/2013 03:40 PM, Daniel Lezcano wrote: >>> On 02/18/2013 06:23 PM, Stéphane Graber wrote: >>>> dpkg spotted that we're not explicitly linking against pthread even though >>>> we use some of its symbols (sem_*). >>> uh ? wait. >>> >>> We shouldn't link against the lib pthread. >>> >>> I don't think sem_* is a symbol coming from the pthread library. >>> >>> Could you give the output of dpkg ? >> From "man sem_open": >> Link with -pthread. > > -pthread, not -lpthread
Oops, misread ... > or -librt > > As lxc is not thread safe, you should prevent to link against the > libpthread because the user will think it is thread safe and that could > lead to some unexpected behavior. Right, please ignore the patch as it's definitely not something we want to do. Would be nice to find a way to make dpkg happy though as this may result into wrongly autogenerated package dependencies (though as in this case it's against libc, it's not really a problem). > Linking against librt should be ok. I don't understand the warning of dpkg. > > Could you check by commenting the lines below if the warning still appear ? > > #if !IS_BIONIC > liblxc_so_LDADD += -lutil -lrt > #endif Building without those fails with: liblxc.so: undefined reference to `sem_post' liblxc.so: undefined reference to `sem_open' liblxc.so: undefined reference to `sem_timedwait' liblxc.so: undefined reference to `sem_wait' liblxc.so: undefined reference to `sem_init' liblxc.so: undefined reference to `sem_destroy' liblxc.so: undefined reference to `sem_close' So maybe it's just the tools being confused... Building with -lutil -lrt does work fine, it's just that dpkg-shlibdeps thinks something's wrong and there doesn't appear to be an easy way to shut it... >> dpkg-shlibdeps output: >> dpkg-shlibdeps: warning: symbol sem_post used by >> debian/liblxc0/usr/lib/x86_64-linux-gnu/liblxc.so.0.9.0.alpha3 found in >> none of the libraries >> dpkg-shlibdeps: warning: symbol sem_open used by >> debian/liblxc0/usr/lib/x86_64-linux-gnu/liblxc.so.0.9.0.alpha3 found in >> none of the libraries >> dpkg-shlibdeps: warning: symbol sem_close used by >> debian/liblxc0/usr/lib/x86_64-linux-gnu/liblxc.so.0.9.0.alpha3 found in >> none of the libraries >> dpkg-shlibdeps: warning: symbol sem_init used by >> debian/liblxc0/usr/lib/x86_64-linux-gnu/liblxc.so.0.9.0.alpha3 found in >> none of the libraries >> dpkg-shlibdeps: warning: symbol sem_timedwait used by >> debian/liblxc0/usr/lib/x86_64-linux-gnu/liblxc.so.0.9.0.alpha3 found in >> none of the libraries >> dpkg-shlibdeps: warning: symbol sem_destroy used by >> debian/liblxc0/usr/lib/x86_64-linux-gnu/liblxc.so.0.9.0.alpha3 found in >> none of the libraries >> dpkg-shlibdeps: warning: symbol sem_wait used by >> debian/liblxc0/usr/lib/x86_64-linux-gnu/liblxc.so.0.9.0.alpha3 found in >> none of the libraries >> >> >> Looking at pthread.so it appears to provide: >> sem_init >> sem_destroy >> sem_open >> sem_close >> sem_unlink >> sem_getvalue >> sem_wait >> sem_trywait >> sem_timedwait >> sem_post >> >>>> Signed-off-by: Stéphane Graber <stgra...@ubuntu.com> >>>> --- >>>> src/lxc/Makefile.am | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/src/lxc/Makefile.am b/src/lxc/Makefile.am >>>> index 8974ca9..a0077aa 100644 >>>> --- a/src/lxc/Makefile.am >>>> +++ b/src/lxc/Makefile.am >>>> @@ -115,7 +115,7 @@ liblxc_so_LDFLAGS = \ >>>> liblxc_so_LDADD = $(CAP_LIBS) $(APPARMOR_LIBS) $(SECCOMP_LIBS) >>>> >>>> if !IS_BIONIC >>>> -liblxc_so_LDADD += -lutil -lrt >>>> +liblxc_so_LDADD += -lutil -lrt -lpthread >>>> endif >>>> >>>> bin_SCRIPTS = \ >> > -- Stéphane Graber Ubuntu developer http://www.ubuntu.com
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