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| author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2016-05-16 10:35:25 -0300 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2016-06-13 08:36:34 -0300 |
| commit | f5c77f78ec03363d5e550c4996deb75ee3f2e32a (patch) | |
| tree | cb4c92983ae34680e3f17acf4549a95d29dd1a02 /sysdeps/unix/sysv/linux/kernel-features.h | |
| parent | 0677af20bb69b91469f0a89aa54bec559a5907e2 (diff) | |
| download | glibc-f5c77f78ec03363d5e550c4996deb75ee3f2e32a.tar.gz glibc-f5c77f78ec03363d5e550c4996deb75ee3f2e32a.tar.xz glibc-f5c77f78ec03363d5e550c4996deb75ee3f2e32a.zip | |
Remove __ASSUME_FUTEX_LOCK_PI
This patch removes __ASSUME_FUTEX_LOCK_PI usage and assumes that
kernel will correctly return if it supports or not
futex_atomic_cmpxchg_inatomic.
Current PI mutex code already has runtime support by calling
prio_inherit_missing and returns ENOTSUP if the futex operation fails
at initialization (it issues a FUTEX_UNLOCK_PI futex operation).
Also, current minimum supported kernel (v3.2) will return ENOSYS if
futex_atomic_cmpxchg_inatomic is not supported in the system:
kernel/futex.c:
2628 long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
2629 u32 __user *uaddr2, u32 val2, u32 val3)
2630 {
2631 int ret = -ENOSYS, cmd = op & FUTEX_CMD_MASK;
[...]
2667 case FUTEX_UNLOCK_PI:
2668 if (futex_cmpxchg_enabled)
2669 ret = futex_unlock_pi(uaddr, flags);
[...]
2686 return ret;
2687 }
The futex_cmpxchg_enabled is initialized by calling cmpxchg_futex_value_locked,
which calls futex_atomic_cmpxchg_inatomic.
For ARM futex_atomic_cmpxchg_inatomic will be either defined (if both
CONFIG_CPU_USE_DOMAINS and CONFIG_SMP are not defined) or use the
default generic implementation that returns ENOSYS.
For m68k is uses the default generic implementation.
For mips futex_atomic_cmpxchg_inatomic will return ENOSYS if cpu has no
'cpu_has_llsc' support (defined by each chip supporte inside kernel).
For sparc, 32-bit kernel will just use default generic implementation,
while 64-bit kernel has support.
Tested on ARM (v3.8 kernel) and x86_64.
* nptl/pthread_mutex_init.c [__ASSUME_FUTEX_LOCK_PI]
(prio_inherit_missing): Remove define.
* sysdeps/unix/sysv/linux/arm/kernel-features.h
(__ASSUME_FUTEX_LOCK_PI): Likewise.
* sysdeps/unix/sysv/linux/kernel-features.h (__ASSUME_FUTEX_LOCK_PI):
Likewise.
* sysdeps/unix/sysv/linux/m68k/kernel-features.h
(__ASSUME_FUTEX_LOCK_PI): Likewise.
* sysdeps/unix/sysv/linux/mips/kernel-features.h
(__ASSUME_FUTEX_LOCK_PI): Likewise.
* sysdeps/unix/sysv/linux/sparc/kernel-features.h
(__ASSUME_FUTEX_LOCK_PI): Likewise.
Diffstat (limited to 'sysdeps/unix/sysv/linux/kernel-features.h')
| -rw-r--r-- | sysdeps/unix/sysv/linux/kernel-features.h | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h index 02c530b9e6..1d3b554f81 100644 --- a/sysdeps/unix/sysv/linux/kernel-features.h +++ b/sysdeps/unix/sysv/linux/kernel-features.h @@ -64,10 +64,6 @@ configurations). */ #define __ASSUME_SET_ROBUST_LIST 1 -/* Support for PI futexes was added in 2.6.18 (but some architectures - lack futex_atomic_cmpxchg_inatomic in some configurations). */ -#define __ASSUME_FUTEX_LOCK_PI 1 - /* Support for private futexes was added in 2.6.22. */ #define __ASSUME_PRIVATE_FUTEX 1 |