This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: Async-signal-safe access to __thread variables from dlopen()ed libraries?
- From: Alexandre Oliva <aoliva at redhat dot com>
- To: Paul Pluzhnikov <ppluzhnikov at google dot com>
- Cc: Ian Lance Taylor <iant at google dot com>, Roland McGrath <roland at hack dot frob dot com>, Richard Henderson <rth at twiddle dot net>, libc-alpha at sourceware dot org, Andrew Hunter <ahh at google dot com>
- Date: Thu, 19 Sep 2013 18:24:59 -0300
- Subject: Re: Async-signal-safe access to __thread variables from dlopen()ed libraries?
- Authentication-results: sourceware.org; auth=none
- References: <20120612193224 dot 8E43619060E at elbrus2 dot mtv dot corp dot google dot com> <4FD8D974 dot 7090903 at twiddle dot net> <20120613182826 dot 0CFAB2C0A3 at topped-with-meat dot com> <CALoOobMtXCw+oe7ZL0=my8YH5st8b1==CasS8i07z6G9DfaX-w at mail dot gmail dot com> <20120613210444 dot 659732C095 at topped-with-meat dot com> <mcr4nqebzok dot fsf at dhcp-172-18-216-180 dot mtv dot corp dot google dot com> <20120614002931 dot ABB762C08B at topped-with-meat dot com> <mcr1uliaeep dot fsf at dhcp-172-18-216-180 dot mtv dot corp dot google dot com> <CALoOobPJ7G7ciRfc2JwzHjsDTg4-_h-SXqeU1zR4WEzoyQhyNg at mail dot gmail dot com>
On Sep 18, 2013, Paul Pluzhnikov <ppluzhnikov@google.com> wrote:
> We really need a TLS that is both async-signal safe, and can be used from
> dlopen()ed shared library.
I suggest you switch to GNU2 TLS, disable lazy relocations, and tune the
static TLS area reserved by glibc (a tunable we still don't have, but
probably should) so that all dlopened libs will fit (and thus be
assigned to) static TLS. You'll not only get the desired safety, but
also a significant speed boost to TLS access, if you can reliably
predict the maximum static TLS segment size the application will need.
--
Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/ FSF Latin America board member
Free Software Evangelist Red Hat Brazil Compiler Engineer