Re: [KJ] remove SPIN_LOCK_UNLOCKED

Milind Arun Choudhary
2007-04-11T04:09:19Z

On 4/11/07, Matthew Wilcox <matthew@wil.cx> wrote:
> On Tue, Apr 10, 2007 at 05:45:07PM -0400, Robert P. J. Day wrote:
> > that works fine if you're defining a single spinlock, but what do you
> > do in cases like this:
> >
> > arch/sparc/lib/atomic32.c: [0 ... (ATOMIC_HASH_SIZE-1)] = SPIN_LOCK_UNLOCKED
> >
> > that is, when you're assigning an array of them? you still need some
> > kind of generic, unnamed spinlock in those circumstances, no?
>
> That's a special case for architecture-only code. It's not to be used
> by drivers.
as per my understanding, [which i should have keyed in earlier]
different places where SPIN_LOCK_UNLOCKED currently appears are

1. static spinlock_t foobar = SPIN_LOCK_UNLOCKED;
needs to be replaced bye DEFINE_SPINLOCK

e.g linux-core/drm_memory_debug.h
-static spinlock_t drm_mem_lock = SPIN_LOCK_UNLOCKED;
+static DEFINE_SPINLOCK(drm_mem_lock);

there are very few occurrences left in the tree i see

2. allocating a data structure dynamically
& initializing the spinlock embedded within

use spin_lock_init()
e.g linux-core/via_dmablit.c

- blitq->blit_lock = SPIN_LOCK_UNLOCKED;
+ spin_lock_init(&blitq->blit_lock);

3. static initialization of structure members
struct foo bar ={
.
.
.
.lock = SPIN_LOCK_UNLOCKED,
.
}
use
struct foo bar ={
.
.
.
.lock = __SPIN_LOCK_UNLOCKED(bar.lock),
.
}

e.g arch/i386/kernel/traps.c
- .lock = SPIN_LOCK_UNLOCKED,
+ .lock = __SPIN_LOCK_UNLOCKED(die.lock),

plenty of these are still there
may be some patches queued

4. arrays of spinlocks
e.g arch/cris/arch-v32/kernel/smp.c

-spinlock_t cris_atomic_locks[] = { [0 ... LOCK_COUNT - 1] =
SPIN_LOCK_UNLOCKED};
+raw_spinlock_t cris_atomic_locks[] = { [0 ... LOCK_COUNT - 1] =
__RAW_SPIN_LOCK_UNLOCKED};

my question is still there in the original post
about spin_lock_init()

CMIIW
Refer:
http://lkml.org/lkml/2005/6/20/47
http://lkml.org/lkml/2007/1/16/90
http://lists.openwall.net/linux-kernel/2007/02/01/258
--
Milind Arun Choudhary