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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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22
sysdeps/unix/sysv/linux/sparc/lowlevellock.h
View File

@@ -24,6 +24,7 @@
#include <bits/pthreadtypes.h>
#include <atomic.h>
#include <kernel-features.h>
#include <errno.h>
#include <lowlevellock-futex.h>
@@ -75,9 +76,13 @@ __lll_cond_lock (int *futex, int private)
#define lll_cond_lock(futex, private) __lll_cond_lock (&(futex), private)
extern int __lll_clocklock_wait (int *futex, clockid_t, const struct timespec *,
extern int __lll_clocklock_wait (int *futex, clockid_t, int val,
const struct timespec *,
int private) attribute_hidden;
#define lll_timedwait(futex, val, clockid, abstime, private) \
__lll_clocklock_wait (futex, val, clockid, abstime, private)
static inline int
__attribute__ ((always_inline))
__lll_clocklock (int *futex, clockid_t clockid,
@@ -87,7 +92,20 @@ __lll_clocklock (int *futex, clockid_t clockid,
int result = 0;
if (__glibc_unlikely (val != 0))
result = __lll_clocklock_wait (futex, clockid, abstime, private);
{
do
{
int oldval = atomic_compare_and_exchange_val_24_acq (futex, val, 1);
if (oldval != 0)
{
result = __lll_clocklock_wait (futex, 2, clockid, abstime,
private);
if (result == EINVAL || result == ETIMEDOUT)
break;
}
}
while (atomic_compare_and_exchange_val_24_acq (futex, val, 0) != 0);
}
return result;
}
#define lll_clocklock(futex, clockid, abstime, private) \