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nptl: Replace non cancellable pause/nanosleep with futex

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To help y2038 work avoid duplicate all the logic of nanosleep on
non cancellable version, the patch replace it with a new futex
operation, lll_timedwait.  The changes are:

  - Add a expected value for __lll_clocklock_wait, so it can be used
    to wait for generic values.

  - Remove its internal atomic operation and move the logic to
    __lll_clocklock.  It makes __lll_clocklock_wait even more generic
    and __lll_clocklock slight faster on fast-path (since it won't
    require a function call anymore).

  - Add lll_timedwait, which uses __lll_clocklock_wait, to replace both
    __pause_nocancel and __nanosleep_nocancel.

It also allows remove the sparc32 __lll_clocklock_wait implementation
(since it is similar to the generic one).

Checked on x86_64-linux-gnu, sparcv9-linux-gnu, and i686-linux-gnu.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Adhemerval Zanella
2019-10-30 15:56:39 -03:00
parent b580327434
commit 215078017f
7 changed files with 56 additions and 82 deletions
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1
sysdeps/sparc/sparc32/lll_timedlock_wait.c
View File

@@ -1 +0,0 @@
/* __lll_clocklock_wait is in lowlevellock.c. */

42
sysdeps/sparc/sparc32/lowlevellock.c
View File

@@ -50,46 +50,4 @@ __lll_lock_wait (int *futex, int private)
}
while (atomic_compare_and_exchange_val_24_acq (futex, 2, 0) != 0);
}
int
__lll_clocklock_wait (int *futex, clockid_t clockid,
const struct timespec *abstime, int private)
{
/* Reject invalid timeouts. */
if (! valid_nanoseconds (abstime->tv_nsec))
return EINVAL;
do
{
struct timespec ts;
struct timespec rt;
/* Get the current time. This can only fail if clockid is not
valid. */
if (__glibc_unlikely (__clock_gettime (clockid, &ts) != 0))
return EINVAL;
/* Compute relative timeout. */
rt.tv_sec = abstime->tv_sec - ts.tv_sec;
rt.tv_nsec = abstime->tv_nsec - ts.tv_nsec;
if (rt.tv_nsec < 0)
{
rt.tv_nsec += 1000000000;
--rt.tv_sec;
}
/* Already timed out? */
if (rt.tv_sec < 0)
return ETIMEDOUT;
/* Wait. */
int oldval = atomic_compare_and_exchange_val_24_acq (futex, 2, 1);
if (oldval != 0)
lll_futex_timed_wait (futex, 2, &rt, private);
}
while (atomic_compare_and_exchange_val_24_acq (futex, 2, 0) != 0);
return 0;
}
#endif