[PATCH 0/2] Linux: Fix '__close_nocancel_nostatus' clobbering 'errno' [BZ #33035]

[Maciej W. Rozycki]

Hi,

 This is v2 of the original change, splitting it to two patches so as to 
make it feasible to backport a minimal fix, as discussed in the review.

 This is a fix for fallout from commit c181840c93d3 ("Consolidate non 
cancellable close call") that caused '__close_nocancel_nostatus' to 
clobber 'errno' on a close(2) failure, a 2.27 regression.

 The original cover letter follows; see individual changes for further 
details.

 Spotted while proofreading an upcoming change for `if_nameindex' and 
`if_nametoindex' to remove support for obsolete pre-2.1.x Linux versions. 

 The offending commit was pushed as obvious without a review, which I 
suppose contributed to the overlooking of the change to semantics caused.  
Then close(2) failures are exceedingly rare where the syscall is made for 
a valid file descriptor, so nobody has reported an issue in the field.

 Verified with a `powerpc64le-linux-gnu' native configuration and by 
inspecting the object code produced for io/close_nocancel_nostatus.o vs 
io/close_nocancel.o.

 OK to apply?

 Previous iterations:

- v1 at: <https://inbox.sourceware.org/libc-alpha/33dd2112-87aa-2e5a-9f6c-e09b1632ef0f@redhat.com/>.

  Maciej