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Re: [PATCH 2/3] Remove __ASSUME_SET_ROBUST_LIST
- From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- To: libc-alpha at sourceware dot org
- Date: Thu, 2 Jun 2016 14:47:04 -0300
- Subject: Re: [PATCH 2/3] Remove __ASSUME_SET_ROBUST_LIST
- Authentication-results: sourceware.org; auth=none
- References: <1463608638-7215-1-git-send-email-adhemerval dot zanella at linaro dot org> <1463608638-7215-2-git-send-email-adhemerval dot zanella at linaro dot org> <5744A65C dot 9060207 at linaro dot org>
Ping.
On 24/05/2016 16:07, Adhemerval Zanella wrote:
> Ping.
>
> On 18/05/2016 18:57, Adhemerval Zanella wrote:
>> This patch removes __ASSUME_SET_ROBUST_LIST usage and assumes that
>> kernel will correctly return if it supports or not
>> futex_atomic_cmpxchg_inatomic.
>>
>> On minimum supported kernel (v3.2 and v2.6.32 for x86) kernel has:
>>
>> 2418 SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head,
>> 2419 size_t, len)
>> 2420 {
>> 2421 if (!futex_cmpxchg_enabled)
>> 2422 return -ENOSYS;
>>
>> The patch also adds the __set_robust_list_avail runtime check for all
>> architectures, since for some the syscall may still return ENOSYS if
>> futex_atomic_cmpxchg_inatomic is not supported (for instance ARM).
>>
>> Tested on armhf (with 3.8 kernel) and x86_64.
>>
>> * nptl/nptl-init.c [__ASSUME_SET_ROBUST_LIST]
>> (__set_robust_list_avail): Remove define.
>> [__NR_set_robust_list] (__pthread_initialize_minimal_internal):
>> Likewise.
>> * nptl/pthreadP.h [__ASSUME_SET_ROBUST_LIST]
>> (__set_robust_list_avail): Likewise.
>> * nptl/pthread_create.c
>> [__NR_set_robust_list && !__ASSUME_SET_ROBUST_LIST]
>> (START_THREAD_DEFN): Likewise.
>> * nptl/pthread_mutex_init.c [!__ASSUME_SET_ROBUST_LIST]
>> (__pthread_mutex_init): Likewise.
>> * sysdeps/unix/sysv/linux/arm/kernel-features.h
>> (__ASSUME_SET_ROBUST_LIST): Likewise.
>> * sysdeps/unix/sysv/linux/kernel-features.h:
>> (__ASSUME_SET_ROBUST_LIST): Likewise.
>> * sysdeps/unix/sysv/linux/m68k/kernel-features.h:
>> (__ASSUME_SET_ROBUST_LIST): Likewise.
>> * sysdeps/unix/sysv/linux/mips/kernel-features.h:
>> (__ASSUME_SET_ROBUST_LIST): Likewise.
>> * sysdeps/unix/sysv/linux/sparc/kernel-features.h:
>> (__ASSUME_SET_ROBUST_LIST): Likewise.
>> ---
>> ChangeLog | 22 ++++++++++++++++++++++
>> nptl/nptl-init.c | 11 ++---------
>> nptl/pthreadP.h | 2 --
>> nptl/pthread_create.c | 8 +-------
>> nptl/pthread_mutex_init.c | 2 --
>> sysdeps/unix/sysv/linux/arm/kernel-features.h | 1 -
>> sysdeps/unix/sysv/linux/kernel-features.h | 5 -----
>> sysdeps/unix/sysv/linux/m68k/kernel-features.h | 1 -
>> sysdeps/unix/sysv/linux/mips/kernel-features.h | 1 -
>> sysdeps/unix/sysv/linux/sparc/kernel-features.h | 1 -
>> 10 files changed, 25 insertions(+), 29 deletions(-)
>>
>> diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
>> index bdbdfed..cad14c7 100644
>> --- a/nptl/nptl-init.c
>> +++ b/nptl/nptl-init.c
>> @@ -48,14 +48,8 @@ int *__libc_multiple_threads_ptr attribute_hidden;
>> size_t __static_tls_size;
>> size_t __static_tls_align_m1;
>>
>> -#ifndef __ASSUME_SET_ROBUST_LIST
>> /* Negative if we do not have the system call and we can use it. */
>> int __set_robust_list_avail;
>> -# define set_robust_list_not_avail() \
>> - __set_robust_list_avail = -1
>> -#else
>> -# define set_robust_list_not_avail() do { } while (0)
>> -#endif
>>
>> #ifndef __ASSUME_FUTEX_CLOCK_REALTIME
>> /* Nonzero if we do not have FUTEX_CLOCK_REALTIME. */
>> @@ -328,7 +322,7 @@ __pthread_initialize_minimal_internal (void)
>> pd->robust_prev = &pd->robust_head;
>> #endif
>> pd->robust_head.list = &pd->robust_head;
>> -#ifdef __NR_set_robust_list
>> +
>> pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
>> - offsetof (pthread_mutex_t,
>> __data.__list.__next));
>> @@ -336,8 +330,7 @@ __pthread_initialize_minimal_internal (void)
>> int res = INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
>> sizeof (struct robust_list_head));
>> if (INTERNAL_SYSCALL_ERROR_P (res, err))
>> -#endif
>> - set_robust_list_not_avail ();
>> + __set_robust_list_avail = -1;
>> }
>>
>> #ifdef __NR_futex
>> diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
>> index 4edc74b..d479a3e 100644
>> --- a/nptl/pthreadP.h
>> +++ b/nptl/pthreadP.h
>> @@ -199,10 +199,8 @@ hidden_proto (__pthread_keys)
>> /* Number of threads running. */
>> extern unsigned int __nptl_nthreads attribute_hidden;
>>
>> -#ifndef __ASSUME_SET_ROBUST_LIST
>> /* Negative if we do not have the system call and we can use it. */
>> extern int __set_robust_list_avail attribute_hidden;
>> -#endif
>>
>> /* Thread Priority Protection. */
>> extern int __sched_fifo_min_prio attribute_hidden;
>> diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
>> index a834063..c3f4087 100644
>> --- a/nptl/pthread_create.c
>> +++ b/nptl/pthread_create.c
>> @@ -271,10 +271,7 @@ START_THREAD_DEFN
>> if (__glibc_unlikely (atomic_exchange_acq (&pd->setxid_futex, 0) == -2))
>> futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE);
>>
>> -#ifdef __NR_set_robust_list
>> -# ifndef __ASSUME_SET_ROBUST_LIST
>> - if (__set_robust_list_avail >= 0)
>> -# endif
>> + if (__glibc_likely (__set_robust_list_avail >= 0))
>> {
>> INTERNAL_SYSCALL_DECL (err);
>> /* This call should never fail because the initial call in init.c
>> @@ -282,7 +279,6 @@ START_THREAD_DEFN
>> INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
>> sizeof (struct robust_list_head));
>> }
>> -#endif
>>
>> #ifdef SIGCANCEL
>> /* If the parent was running cancellation handlers while creating
>> @@ -388,7 +384,6 @@ START_THREAD_DEFN
>> the breakpoint reports TD_THR_RUN state rather than TD_THR_ZOMBIE. */
>> atomic_bit_set (&pd->cancelhandling, EXITING_BIT);
>>
>> -#ifndef __ASSUME_SET_ROBUST_LIST
>> /* If this thread has any robust mutexes locked, handle them now. */
>> # ifdef __PTHREAD_MUTEX_HAVE_PREV
>> void *robust = pd->robust_head.list;
>> @@ -419,7 +414,6 @@ START_THREAD_DEFN
>> }
>> while (robust != (void *) &pd->robust_head);
>> }
>> -#endif
>>
>> /* Mark the memory of the stack as usable to the kernel. We free
>> everything except for the space used for the TCB itself. */
>> diff --git a/nptl/pthread_mutex_init.c b/nptl/pthread_mutex_init.c
>> index 6e5acb6..6aef890 100644
>> --- a/nptl/pthread_mutex_init.c
>> +++ b/nptl/pthread_mutex_init.c
>> @@ -91,11 +91,9 @@ __pthread_mutex_init (pthread_mutex_t *mutex,
>>
>> if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST) != 0)
>> {
>> -#ifndef __ASSUME_SET_ROBUST_LIST
>> if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_PSHARED) != 0
>> && __set_robust_list_avail < 0)
>> return ENOTSUP;
>> -#endif
>>
>> mutex->__data.__kind |= PTHREAD_MUTEX_ROBUST_NORMAL_NP;
>> }
>> diff --git a/sysdeps/unix/sysv/linux/arm/kernel-features.h b/sysdeps/unix/sysv/linux/arm/kernel-features.h
>> index 6ca607e..4012751 100644
>> --- a/sysdeps/unix/sysv/linux/arm/kernel-features.h
>> +++ b/sysdeps/unix/sysv/linux/arm/kernel-features.h
>> @@ -24,7 +24,6 @@
>> configuration. */
>> #if __LINUX_KERNEL_VERSION < 0x030E03
>> # undef __ASSUME_REQUEUE_PI
>> -# undef __ASSUME_SET_ROBUST_LIST
>> #endif
>>
>> /* Define this if your 32-bit syscall API requires 64-bit register
>> diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
>> index 43b72b1..45edad5 100644
>> --- a/sysdeps/unix/sysv/linux/kernel-features.h
>> +++ b/sysdeps/unix/sysv/linux/kernel-features.h
>> @@ -59,11 +59,6 @@
>> they were introduced in 2.6.17-rc1, on SH in 2.6.19-rc1. */
>> #define __ASSUME_ATFCTS 1
>>
>> -/* Support for inter-process robust mutexes was added in 2.6.17 (but
>> - some architectures lack futex_atomic_cmpxchg_inatomic in some
>> - configurations). */
>> -#define __ASSUME_SET_ROBUST_LIST 1
>> -
>> /* Support for private futexes was added in 2.6.22. */
>> #define __ASSUME_PRIVATE_FUTEX 1
>>
>> diff --git a/sysdeps/unix/sysv/linux/m68k/kernel-features.h b/sysdeps/unix/sysv/linux/m68k/kernel-features.h
>> index 9e7f0e1..bec9539 100644
>> --- a/sysdeps/unix/sysv/linux/m68k/kernel-features.h
>> +++ b/sysdeps/unix/sysv/linux/m68k/kernel-features.h
>> @@ -52,5 +52,4 @@
>> /* No support for PI futexes or robust mutexes before 3.10 for m68k. */
>> #if __LINUX_KERNEL_VERSION < 0x030a00
>> # undef __ASSUME_REQUEUE_PI
>> -# undef __ASSUME_SET_ROBUST_LIST
>> #endif
>> diff --git a/sysdeps/unix/sysv/linux/mips/kernel-features.h b/sysdeps/unix/sysv/linux/mips/kernel-features.h
>> index 09d5ece..3640b5f 100644
>> --- a/sysdeps/unix/sysv/linux/mips/kernel-features.h
>> +++ b/sysdeps/unix/sysv/linux/mips/kernel-features.h
>> @@ -25,7 +25,6 @@
>> emulating LL/SC. */
>> #if __mips == 1 || defined _MIPS_ARCH_R5900
>> # undef __ASSUME_REQUEUE_PI
>> -# undef __ASSUME_SET_ROBUST_LIST
>> #endif
>>
>> /* Define this if your 32-bit syscall API requires 64-bit register
>> diff --git a/sysdeps/unix/sysv/linux/sparc/kernel-features.h b/sysdeps/unix/sysv/linux/sparc/kernel-features.h
>> index 69c9c7c..dc7c4aa 100644
>> --- a/sysdeps/unix/sysv/linux/sparc/kernel-features.h
>> +++ b/sysdeps/unix/sysv/linux/sparc/kernel-features.h
>> @@ -35,5 +35,4 @@
>> futex_atomic_cmpxchg_inatomic. */
>> #if !defined __arch64__ && !defined __sparc_v9__
>> # undef __ASSUME_REQUEUE_PI
>> -# undef __ASSUME_SET_ROBUST_LIST
>> #endif
>>