[MTASCsft PATCH 03/??] MT-, AS- and AC-Safety docs: manual/arith.texi

[Alexandre Oliva]

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