read_trylock() is broken on sparc32 (doesn't build and didn't work
right, actually). Proposed fix:
- make "writer holds lock" distinguishable from "reader tries to grab
lock"
- have __raw_read_trylock() try to acquire the mutex (in LSB of lock),
terminating spin if we see that there's writer holding it. Then do
the rest as we do in read_lock().
Thanks to Ingo for discussion...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
7a39f52202