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author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2016-05-16 10:35:25 -0300 |
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committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2016-06-13 08:36:34 -0300 |
commit | f5c77f78ec03363d5e550c4996deb75ee3f2e32a (patch) | |
tree | cb4c92983ae34680e3f17acf4549a95d29dd1a02 /ChangeLog.13 | |
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 'ChangeLog.13')
0 files changed, 0 insertions, 0 deletions