get_futex_key — Get parameters which are the keys for a futex
int get_futex_key ( | u32 __user * uaddr, |
| int fshared, | |
| union futex_key * key, | |
int rw); |
uaddrvirtual address of the futex
fshared0 for a PROCESS_PRIVATE futex, 1 for PROCESS_SHARED
keyaddress where result is stored.
rwmapping needs to be read/write (values: VERIFY_READ, VERIFY_WRITE)
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.