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GET_FUTEX_KEY(9) Futex API reference GET_FUTEX_KEY(9)

NAME

get_futex_key - Get parameters which are the keys for a futex

SYNOPSIS

int get_futex_key(u32 __user * uaddr, int fshared, union futex_key * key, int rw);

ARGUMENTS

uaddr
virtual address of the futex

fshared

0 for a PROCESS_PRIVATE futex, 1 for PROCESS_SHARED

key

address where result is stored.

rw

mapping needs to be read/write (values: VERIFY_READ, VERIFY_WRITE)

RETURN

a negative error code or 0

The key words are stored in *key on success.

For shared mappings, it's (page->index, file_inode(vma->vm_file), offset_within_page). For private mappings, it's (uaddr, current->mm). We can usually work out the index without swapping in the page.

lock_page might sleep, the caller should not hold a spinlock.

AUTHOR

Rusty Russell <rusty@rustcorp.com.au>
Author.

COPYRIGHT

April 2019 Kernel Hackers Manual 4.9.