[20/26] Linux: set_robust_list syscall number is always available
diff mbox series

Message ID d767ca43b8c6b28efb5ad12051f6629e4ceae642.1581279333.git.fweimer@redhat.com
State New
Headers show
Series
  • Linux cleanups enabled by built-in system call tables
Related show

Commit Message

Florian Weimer Feb. 9, 2020, 8:21 p.m. UTC
Due to the built-in tables, __NR_set_robust_list is always defined
(although it may not be available at run time).
---
 nptl/nptl-init.c      |  4 ----
 nptl/pthread_create.c |  6 ++----
 sysdeps/nptl/fork.c   | 10 ++++------
 3 files changed, 6 insertions(+), 14 deletions(-)

Comments

Adhemerval Zanella Feb. 27, 2020, 11:45 p.m. UTC | #1
On 09/02/2020 17:21, Florian Weimer wrote:
> Due to the built-in tables, __NR_set_robust_list is always defined
> (although it may not be available at run time).

LGTM, thanks. 

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

> ---
>  nptl/nptl-init.c      |  4 ----
>  nptl/pthread_create.c |  6 ++----
>  sysdeps/nptl/fork.c   | 10 ++++------
>  3 files changed, 6 insertions(+), 14 deletions(-)
> 
> diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
> index 1877248014..373be89c95 100644
> --- a/nptl/nptl-init.c
> +++ b/nptl/nptl-init.c
> @@ -129,11 +129,9 @@ static
>  void
>  __nptl_set_robust (struct pthread *self)
>  {
> -#ifdef __NR_set_robust_list
>    INTERNAL_SYSCALL_DECL (err);
>    INTERNAL_SYSCALL (set_robust_list, err, 2, &self->robust_head,
>  		    sizeof (struct robust_list_head));
> -#endif
>  }
>  
>  
> @@ -254,7 +252,6 @@ __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));
> @@ -262,7 +259,6 @@ __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 ();
>    }
>  

I wonder if it would be better to refactor the __nptl_set_robust to
simplify the '__set_robust_list_avail' handling. Something like:

--
void
__nptl_set_robust (struct pthread *pd)
{
#ifdef __ASSUME_SET_ROBUST_LIST
  static int set_robust_supported = true;
  if (atomic_load_relaxed (&getdents64_supported))
    {
      int res = INTERNAL_SYSCALL_CALL (set_robust_list, &pd->robust_head,
				       sizeof (struct robust_list_head));
      if (INTERNAL_SYSCALL_ERROR_P (res))
	atomic_store_relaxed (&getdents64_supported, false);
    }
#endif
}
--

> diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
> index d3fd58730c..58706b4160 100644
> --- a/nptl/pthread_create.c
> +++ b/nptl/pthread_create.c
> @@ -389,10 +389,9 @@ 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
> +#ifndef __ASSUME_SET_ROBUST_LIST
>    if (__set_robust_list_avail >= 0)
> -# endif
> +#endif
>      {
>        INTERNAL_SYSCALL_DECL (err);
>        /* This call should never fail because the initial call in init.c
> @@ -400,7 +399,6 @@ START_THREAD_DEFN
>        INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
>  			sizeof (struct robust_list_head));
>      }
> -#endif
>  
>    /* If the parent was running cancellation handlers while creating
>       the thread the new thread inherited the signal mask.  Reset the

Ok.

> diff --git a/sysdeps/nptl/fork.c b/sysdeps/nptl/fork.c
> index f5cf88d68c..5091a000e3 100644
> --- a/sysdeps/nptl/fork.c
> +++ b/sysdeps/nptl/fork.c
> @@ -83,7 +83,6 @@ __libc_fork (void)
>        if (__fork_generation_pointer != NULL)
>  	*__fork_generation_pointer += __PTHREAD_ONCE_FORK_GEN_INCR;
>  
> -#ifdef __NR_set_robust_list
>        /* Initialize the robust mutex list setting in the kernel which has
>  	 been reset during the fork.  We do not check for errors because if
>  	 it fails here, it must have failed at process startup as well and
> @@ -94,19 +93,18 @@ __libc_fork (void)
>  	 inherit the correct value from the parent.  We do not need to clear
>  	 the pending operation because it must have been zero when fork was
>  	 called.  */
> -# if __PTHREAD_MUTEX_HAVE_PREV
> +#if __PTHREAD_MUTEX_HAVE_PREV
>        self->robust_prev = &self->robust_head;
> -# endif
> +#endif
>        self->robust_head.list = &self->robust_head;
> -# ifdef SHARED
> +#ifdef SHARED
>        if (__builtin_expect (__libc_pthread_functions_init, 0))
>  	PTHFCT_CALL (ptr_set_robust, (self));
> -# else
> +#else
>        extern __typeof (__nptl_set_robust) __nptl_set_robust
>  	__attribute__((weak));
>        if (__builtin_expect (__nptl_set_robust != NULL, 0))
>  	__nptl_set_robust (self);
> -# endif
>  #endif
>  
>        /* Reset the lock state in the multi-threaded case.  */
> 

Ok.

Patch
diff mbox series

diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
index 1877248014..373be89c95 100644
--- a/nptl/nptl-init.c
+++ b/nptl/nptl-init.c
@@ -129,11 +129,9 @@  static
 void
 __nptl_set_robust (struct pthread *self)
 {
-#ifdef __NR_set_robust_list
   INTERNAL_SYSCALL_DECL (err);
   INTERNAL_SYSCALL (set_robust_list, err, 2, &self->robust_head,
 		    sizeof (struct robust_list_head));
-#endif
 }
 
 
@@ -254,7 +252,6 @@  __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));
@@ -262,7 +259,6 @@  __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 ();
   }
 
diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index d3fd58730c..58706b4160 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -389,10 +389,9 @@  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
+#ifndef __ASSUME_SET_ROBUST_LIST
   if (__set_robust_list_avail >= 0)
-# endif
+#endif
     {
       INTERNAL_SYSCALL_DECL (err);
       /* This call should never fail because the initial call in init.c
@@ -400,7 +399,6 @@  START_THREAD_DEFN
       INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
 			sizeof (struct robust_list_head));
     }
-#endif
 
   /* If the parent was running cancellation handlers while creating
      the thread the new thread inherited the signal mask.  Reset the
diff --git a/sysdeps/nptl/fork.c b/sysdeps/nptl/fork.c
index f5cf88d68c..5091a000e3 100644
--- a/sysdeps/nptl/fork.c
+++ b/sysdeps/nptl/fork.c
@@ -83,7 +83,6 @@  __libc_fork (void)
       if (__fork_generation_pointer != NULL)
 	*__fork_generation_pointer += __PTHREAD_ONCE_FORK_GEN_INCR;
 
-#ifdef __NR_set_robust_list
       /* Initialize the robust mutex list setting in the kernel which has
 	 been reset during the fork.  We do not check for errors because if
 	 it fails here, it must have failed at process startup as well and
@@ -94,19 +93,18 @@  __libc_fork (void)
 	 inherit the correct value from the parent.  We do not need to clear
 	 the pending operation because it must have been zero when fork was
 	 called.  */
-# if __PTHREAD_MUTEX_HAVE_PREV
+#if __PTHREAD_MUTEX_HAVE_PREV
       self->robust_prev = &self->robust_head;
-# endif
+#endif
       self->robust_head.list = &self->robust_head;
-# ifdef SHARED
+#ifdef SHARED
       if (__builtin_expect (__libc_pthread_functions_init, 0))
 	PTHFCT_CALL (ptr_set_robust, (self));
-# else
+#else
       extern __typeof (__nptl_set_robust) __nptl_set_robust
 	__attribute__((weak));
       if (__builtin_expect (__nptl_set_robust != NULL, 0))
 	__nptl_set_robust (self);
-# endif
 #endif
 
       /* Reset the lock state in the multi-threaded case.  */