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Re: [MTASCsft PATCH 03/??] MT-, AS- and AC-Safety docs: manual/arith.texi
- From: Alexandre Oliva <aoliva at redhat dot com>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>
- Cc: <codonell at redhat dot com>, <libc-alpha at sourceware dot org>
- Date: Fri, 24 Jan 2014 10:41:42 -0200
- Subject: Re: [MTASCsft PATCH 03/??] MT-, AS- and AC-Safety docs: manual/arith.texi
- Authentication-results: sourceware.org; auth=none
- References: <ortxelb5zd dot fsf at livre dot home> <or4n4uoncj dot fsf at livre dot home> <orr47yn3kl dot fsf_-_ at livre dot home> <Pine dot LNX dot 4 dot 64 dot 1401231606360 dot 31884 at digraph dot polyomino dot org dot uk> <ory526lfrz dot fsf at livre dot home> <Pine dot LNX dot 4 dot 64 dot 1401231830130 dot 31884 at digraph dot polyomino dot org dot uk>
On Jan 23, 2014, "Joseph S. Myers" <joseph@codesourcery.com> wrote:
> I think documenting AC-Safety should include making clear what cleanup
> handlers may do, as well as the effect of cancellation during a given
> function. That may mean a note about setting a known FP environment.
How about this?
diff --git a/manual/intro.texi b/manual/intro.texi
index 03c1abe..27fe760 100644
--- a/manual/intro.texi
+++ b/manual/intro.texi
@@ -252,6 +252,15 @@ guarantees beyond these three functions, but does document which
functions are presently AC-Safe. This documentation is provided for use
by @theglibc{} developers.
+Just like signal handlers, cleanup handlers must configure the floating
+point environment they require, because they cannot assume it to be
+configured in any specific way, particularly when asynchronous
+cancellation is enabled. It is even possible that the floating point
+environment will be encountered in an internally inconsistent state,
+e.g. because of cancellation between reconfiguring two floating point
+units, or even if the reconfiguration of a single floating point unit
+cannot be performed atomically.
+
@item
@cindex MT-Unsafe
--
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 Toolchain Engineer