Historically, Android defaulted to EXPLICIT but with a special case
because SCHED_NORMAL/priority 0 was awkward. Because the code couldn't
actually tell whether SCHED_NORMAL/priority 0 was a genuine attempt to
explicitly set those attributes (because the parent thread is SCHED_FIFO,
say) or just because the pthread_attr_t was left at its defaults.
Now we support INHERIT, we could call sched_getscheduler to see whether
we actually need to call sched_setscheduler, but since the major cost
is the fixed syscall overhead, we may as well just conservatively
call sched_setscheduler and let the kernel decide whether it's a
no-op. (Especially because we'd then have to add both sched_getscheduler
and sched_setscheduler to any seccomp filter.)
Platform code (or app code that only needs to support >= P) can actually
add a call to pthread_attr_setinheritsched to say that they just want
to inherit (if they know that none of their threads actually mess with
scheduler attributes at all), which will save them a sched_setscheduler
call except in the doubly-special case of SCHED_RESET_ON_FORK (which we
do handle).
An alternative would be "make pthread_attr_setschedparams and
pthread_attr_setschedprio set EXPLICIT and change the platform default
to INHERIT", but even though I can only think of weird pathological
examples where anyone would notice that change, that behavior -- of
pthread_attr_setschedparams/pthread_attr_setschedprio overriding an
earlier call to pthread_attr_setinheritsched -- isn't allowed by POSIX
(whereas defaulting to EXPLICIT is).
If we have a lot of trouble with this change in the app compatibility
testing phase, though, we'll want to reconsider this decision!
-*-
This change also removes a comment about setting the scheduler attributes
in main_thread because we'd have to actually keep them up to date,
and it's not clear that doing so would be worth the trouble.
Also make async_safe_format_log preserve errno so we don't have to be
so careful around it.
Bug: http://b/67471710
Test: ran tests
Change-Id: Idd026c4ce78a536656adcb57aa2e7b2c616eeddf
Went through the POSIX spec for the _POSIX* and _XOPEN* constants.
Bug: http://b/32776472
Test: ran tests
Change-Id: I389100dbc7de354eae9056e44b0a7fa8c37374e3
The newest of these clocks was added in Linux 2.6.12, so no need for runtime
checks.
Add CTS tests that we can actually use the various clocks.
Bug: http://b/67458266
Test: ran tests
Change-Id: I3cfd7982043d6f8d4ebdc2b29e8722334f443ce5
We've had pthread_*_setpshared for long enough that there are no
__INTRODUCED_IN guards.
Found because fio's configure script was confused by this.
Bug: N/A
Test: ran tests
Change-Id: I07b4d937741e4dcd7e615f2371b17c827341917a
I made a mistake caught by code review earlier, so let's try to be
safer by default.
This patch also moves all our "forwarding" headers to the guardless
just-include-the-other-thing style that we usually use. (Where we
have a comment explaining where the header comes from, I've kept
that.)
Change-Id: I37342cf5e2563c6a269b2ba61a697069b1c7913b
This has been requested a few times over the years. This is basically
a very late rebase of https://android-review.googlesource.com/45470
which was abandoned years ago. One addition is that this version has
_FILE_OFFSET_BITS=64 support.
POSIX puts this in <unistd.h>. glibc also has it in <fcntl.h>.
Bug: http://b/13077650
Change-Id: I5862b1dc326e326c01ad92438ecc1578d19ba739
2016-01-26 11:09:44 -08:00
Renamed from libc/include/machine/posix_limits.h (Browse further)
