This is the mail archive of the libc-alpha@sourceware.org mailing list for the glibc project.

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]
Other format:	[Raw text]

[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: Wed, 18 May 2016 18:57:17 -0300
Subject: [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>

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
-- 
2.7.4

Follow-Ups:
- Re: [PATCH 2/3] Remove __ASSUME_SET_ROBUST_LIST
  - From: Adhemerval Zanella

References:
- [PATCH 1/3] Remove __ASSUME_FUTEX_LOCK_PI
  - From: Adhemerval Zanella

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]