On Wed, Mar 27, 2013 at 12:09:43AM -0700, Mike Turquette wrote:
- /* set context for any reentrant calls */
- atomic_set(&prepare_context, (int) get_current());
...
- if (mutex_is_locked(&prepare_lock))
if ((void *) atomic_read(&prepare_context) == get_current())return true;
If you really want to do it like this, then the _correct_ way to do it is:
if (atomic_read(&prepare_context) == (int)get_current())
So that any effects from the cast are the same in both parts. Otherwise, you will be running into the possibility that a cast could do something like truncate the returned value, resulting in the test condition using pointers always being false.
It's not that much of a problem on ARM, but it's a matter of good programming discpline that such issues are avoided.
Even better would be to cast it to unsigned long - this is the value which the atomic types use, and that is less likely to be truncated. It also helps to avoid the possibility of compilers complaining about a narrowing cast too - especially as the entire Linux kernel assumes that pointers can be cast to unsigned long and back again with no loss.