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

u32 __user * uaddr

virtual address of the futex

int fshared

0 for a PROCESS_PRIVATE futex, 1 for PROCESS_SHARED

union futex_key * key

address where result is stored.

int 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.