[PATCH] Remove futex_supports_pshared
Adhemerval Zanella Netto
adhemerval.zanella@linaro.org
Mon Sep 8 12:58:08 GMT 2025
On 07/09/25 12:05, Andreas Schwab wrote:
> Both NPTL and HTL support PTHREAD_PROCESS_SHARED, and since the removal of
> the NaCL port there are no other pthread implementations.
LGTM, thanks.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> nptl/pthread_barrierattr_setpshared.c | 6 ++----
> nptl/pthread_condattr_setpshared.c | 6 ++----
> nptl/pthread_mutexattr_setpshared.c | 6 ++----
> nptl/pthread_rwlockattr_setpshared.c | 6 ++----
> nptl/sem_init.c | 11 +----------
> sysdeps/htl/futex-internal.h | 14 --------------
> sysdeps/nptl/futex-internal.h | 20 --------------------
> sysdeps/pthread/sem_open.c | 9 ---------
> 8 files changed, 9 insertions(+), 69 deletions(-)
>
> diff --git a/nptl/pthread_barrierattr_setpshared.c b/nptl/pthread_barrierattr_setpshared.c
> index ae58a2b4fa..74b025818b 100644
> --- a/nptl/pthread_barrierattr_setpshared.c
> +++ b/nptl/pthread_barrierattr_setpshared.c
> @@ -17,15 +17,13 @@
>
> #include <errno.h>
> #include "pthreadP.h"
> -#include <futex-internal.h>
> #include <shlib-compat.h>
>
> int
> __pthread_barrierattr_setpshared (pthread_barrierattr_t *attr, int pshared)
> {
> - int err = futex_supports_pshared (pshared);
> - if (err != 0)
> - return err;
> + if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED)
> + return EINVAL;
>
> ((struct pthread_barrierattr *) attr)->pshared = pshared;
>
> diff --git a/nptl/pthread_condattr_setpshared.c b/nptl/pthread_condattr_setpshared.c
> index 13e6f78d18..2ab3e9f9e9 100644
> --- a/nptl/pthread_condattr_setpshared.c
> +++ b/nptl/pthread_condattr_setpshared.c
> @@ -17,15 +17,13 @@
>
> #include <errno.h>
> #include <pthreadP.h>
> -#include <futex-internal.h>
> #include <shlib-compat.h>
>
> int
> __pthread_condattr_setpshared (pthread_condattr_t *attr, int pshared)
> {
> - int err = futex_supports_pshared (pshared);
> - if (err != 0)
> - return err;
> + if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED)
> + return EINVAL;
>
> int *valuep = &((struct pthread_condattr *) attr)->value;
>
> diff --git a/nptl/pthread_mutexattr_setpshared.c b/nptl/pthread_mutexattr_setpshared.c
> index fea8ee6d70..d7ef3430c3 100644
> --- a/nptl/pthread_mutexattr_setpshared.c
> +++ b/nptl/pthread_mutexattr_setpshared.c
> @@ -17,7 +17,6 @@
>
> #include <errno.h>
> #include <pthreadP.h>
> -#include <futex-internal.h>
> #include <shlib-compat.h>
>
> int
> @@ -25,9 +24,8 @@ __pthread_mutexattr_setpshared (pthread_mutexattr_t *attr, int pshared)
> {
> struct pthread_mutexattr *iattr;
>
> - int err = futex_supports_pshared (pshared);
> - if (err != 0)
> - return err;
> + if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED)
> + return EINVAL;
>
> iattr = (struct pthread_mutexattr *) attr;
>
> diff --git a/nptl/pthread_rwlockattr_setpshared.c b/nptl/pthread_rwlockattr_setpshared.c
> index c32d99515a..655bcef726 100644
> --- a/nptl/pthread_rwlockattr_setpshared.c
> +++ b/nptl/pthread_rwlockattr_setpshared.c
> @@ -17,7 +17,6 @@
>
> #include <errno.h>
> #include "pthreadP.h"
> -#include <futex-internal.h>
> #include <shlib-compat.h>
>
> int
> @@ -25,9 +24,8 @@ __pthread_rwlockattr_setpshared (pthread_rwlockattr_t *attr, int pshared)
> {
> struct pthread_rwlockattr *iattr;
>
> - int err = futex_supports_pshared (pshared);
> - if (err != 0)
> - return err;
> + if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED)
> + return EINVAL;
>
> iattr = (struct pthread_rwlockattr *) attr;
>
> diff --git a/nptl/sem_init.c b/nptl/sem_init.c
> index cf17411270..76e1aceb70 100644
> --- a/nptl/sem_init.c
> +++ b/nptl/sem_init.c
> @@ -20,7 +20,6 @@
> #include <shlib-compat.h>
> #include "semaphoreP.h"
> #include <kernel-features.h>
> -#include <futex-internal.h>
>
>
> int
> @@ -34,13 +33,6 @@ __new_sem_init (sem_t *sem, int pshared, unsigned int value)
> __set_errno (EINVAL);
> return -1;
> }
> - pshared = pshared != 0 ? PTHREAD_PROCESS_SHARED : PTHREAD_PROCESS_PRIVATE;
> - int err = futex_supports_pshared (pshared);
> - if (err != 0)
> - {
> - __set_errno (err);
> - return -1;
> - }
>
> /* Map to the internal type. */
> struct new_sem *isem = (struct new_sem *) sem;
> @@ -55,8 +47,7 @@ __new_sem_init (sem_t *sem, int pshared, unsigned int value)
> isem->nwaiters = 0;
> #endif
>
> - isem->private = (pshared == PTHREAD_PROCESS_PRIVATE
> - ? FUTEX_PRIVATE : FUTEX_SHARED);
> + isem->private = (pshared == 0 ? FUTEX_PRIVATE : FUTEX_SHARED);
>
> return 0;
> }
> diff --git a/sysdeps/htl/futex-internal.h b/sysdeps/htl/futex-internal.h
> index 4976fa07c2..7380290183 100644
> --- a/sysdeps/htl/futex-internal.h
> +++ b/sysdeps/htl/futex-internal.h
> @@ -22,18 +22,4 @@
>
> #include <pthread.h>
>
> -/* Returns EINVAL if PSHARED is neither PTHREAD_PROCESS_PRIVATE nor
> - PTHREAD_PROCESS_SHARED; otherwise, returns 0 if PSHARED is supported, and
> - ENOTSUP if not. */
> -static __always_inline int
> -futex_supports_pshared (int pshared)
> -{
> - if (__glibc_likely (pshared == PTHREAD_PROCESS_PRIVATE))
> - return 0;
> - else if (pshared == PTHREAD_PROCESS_SHARED)
> - return 0;
> - else
> - return EINVAL;
> -}
> -
> #endif /* futex-internal.h */
> diff --git a/sysdeps/nptl/futex-internal.h b/sysdeps/nptl/futex-internal.h
> index 301daccbb1..2533c91dd3 100644
> --- a/sysdeps/nptl/futex-internal.h
> +++ b/sysdeps/nptl/futex-internal.h
> @@ -38,12 +38,6 @@
> return values that callers need to handle.
>
> The private flag must be either FUTEX_PRIVATE or FUTEX_SHARED.
> - FUTEX_PRIVATE is always supported, and the implementation can internally
> - use FUTEX_SHARED when FUTEX_PRIVATE is requested. FUTEX_SHARED is not
> - necessarily supported (use futex_supports_pshared to detect this).
> -
> - We expect callers to only use these operations if futexes and the
> - specific futex operations being used are supported (e.g., FUTEX_SHARED).
>
> Given that waking other threads waiting on a futex involves concurrent
> accesses to the futex word, you must use atomic operations to access the
> @@ -95,20 +89,6 @@ futex_fatal_error (void)
> We expect a Linux kernel version of 2.6.22 or more recent (since this
> version, EINTR is not returned on spurious wake-ups anymore). */
>
> -/* Returns EINVAL if PSHARED is neither PTHREAD_PROCESS_PRIVATE nor
> - PTHREAD_PROCESS_SHARED; otherwise, returns 0 if PSHARED is supported, and
> - ENOTSUP if not. */
> -static __always_inline int
> -futex_supports_pshared (int pshared)
> -{
> - if (__glibc_likely (pshared == PTHREAD_PROCESS_PRIVATE))
> - return 0;
> - else if (pshared == PTHREAD_PROCESS_SHARED)
> - return 0;
> - else
> - return EINVAL;
> -}
> -
> /* Atomically wrt other futex operations on the same futex, this blocks iff
> the value *FUTEX_WORD matches the expected value. This is
> semantically equivalent to:
> diff --git a/sysdeps/pthread/sem_open.c b/sysdeps/pthread/sem_open.c
> index 992786e01b..143b60a0d0 100644
> --- a/sysdeps/pthread/sem_open.c
> +++ b/sysdeps/pthread/sem_open.c
> @@ -23,7 +23,6 @@
> #include "semaphoreP.h"
> #include <shm-directory.h>
> #include <sem_routines.h>
> -#include <futex-internal.h>
> #include <libc-lock.h>
> #include <string.h>
> #include <shlib-compat.h>
> @@ -36,14 +35,6 @@ __sem_open (const char *name, int oflag, ...)
> int fd;
> sem_t *result;
>
> - /* Check that shared futexes are supported. */
> - int err = futex_supports_pshared (PTHREAD_PROCESS_SHARED);
> - if (err != 0)
> - {
> - __set_errno (err);
> - return SEM_FAILED;
> - }
> -
> struct shmdir_name dirname;
> int ret = __shm_get_name (&dirname, name, true);
> if (ret != 0)
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