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Re: Support six-argument syscalls from C for 32-bit x86, use generic lowlevellock-futex.h (bug 18138)
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Carlos O'Donell <carlos at redhat dot com>
- Cc: <libc-alpha at sourceware dot org>, <roland at hack dot frob dot com>, <triegel at redhat dot com>
- Date: Mon, 23 Mar 2015 16:37:11 +0000
- Subject: Re: Support six-argument syscalls from C for 32-bit x86, use generic lowlevellock-futex.h (bug 18138)
- Authentication-results: sourceware.org; auth=none
- References: <alpine dot DEB dot 2 dot 10 dot 1503210026500 dot 5144 at digraph dot polyomino dot org dot uk> <55103547 dot 7040202 at redhat dot com>
On Mon, 23 Mar 2015, Carlos O'Donell wrote:
> The last time I changed the 6-argument syscall code for hppa, I didn't
> notice I'd gotten it wrong until I reran more userspace tests like
> running firefox with the new glibc.
> What kind of confidence do we have here without a test that exercises
> the 6-argument syscall?
All the sem_timedwait tests (possibly tests for some other NPTL functions
as well) exercise this code through use of lll_futex_timed_wait_bitset.
> Is it possible to add an x86-specific test to show this is working
> as intended?
The only six-argument syscall usage (inline from C, as opposed to from
syscalls.list) is in lowlevellock-futex.h, and I think the NPTL tests
cover that. In fact only lll_futex_timed_wait_bitset gets used on x86
because of .S versions of pthread_cond_* where the other lll_futex_*
macros with six-argument syscalls get used in the C versions.
So I don't think there's any useful addition of tests possible here
(although of course if we do get future support for tests running in some
form of container where a test can safely change the system clock, then
adding the original test for bug 18138 to run in such a context makes
Joseph S. Myers