NAME

       FUTEX_TRYLOCK_PI - try to lock a priority-inheritance futex

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <linux/futex.h>  /* Definition of FUTEX_* constants */
       #include <sys/syscall.h>  /* Definition of SYS_* constants */
       #include <unistd.h>

       long syscall(SYS_futex, uint32_t *uaddr, FUTEX_TRYLOCK_PI);

DESCRIPTION

       This  operation  tries  to acquire the lock at uaddr.  It is invoked when a user-space atomic acquire did
       not succeed because the futex word was not 0.

       Because the kernel has access to more state information than user space, acquisition of  the  lock  might
       succeed  if performed by the kernel in cases where the futex word (i.e., the state information accessible
       to use-space) contains stale state (FUTEX_WAITERS and/or FUTEX_OWNER_DIED).  This  can  happen  when  the
       owner  of  the futex died.  User space cannot handle this condition in a race-free manner, but the kernel
       can fix this up and acquire the futex.

RETURN VALUE

       On error, -1 is returned, and errno is set to indicate the error.

       On success, FUTEX_TRYLOCK_PI Returns 0 if the futex was successfully locked.

ERRORS

       See futex(2).

       EAGAIN The futex owner thread ID of uaddr is about to exit, but has not yet handled  the  internal  state
              cleanup.  Try again.

       EDEADLK
              The futex word at uaddr is already locked by the caller.

       EINVAL The  kernel  detected an inconsistency between the user-space state at uaddr and the kernel state.
              This indicates either state corruption or that the kernel found a waiter on uaddr which is waiting
              via FUTEX_WAIT(2const) or FUTEX_WAIT_BITSET(2const).

       ENOMEM The kernel could not allocate memory to hold state information.

       ENOSYS A run-time check determined that the operation is not available.  The PI-futex operations are  not
              implemented on all architectures and are not supported on some CPU variants.

       EPERM  The  caller is not allowed to attach itself to the futex at uaddr.  (This may be caused by a state
              corruption in user space.)

       ESRCH  The thread ID in the futex word at uaddr does not exist.

STANDARDS

       Linux.

HISTORY

       Linux 2.6.18.

SEE ALSO

       futex(2)

Linux man-pages 6.16                               2025-09-21                           FUTEX_TRYLOCK_PI(2const)