w1: introduce a slave mutex for serializing IO

w1 devices need a mutex to serial IO.  Most use master->mutex.
However that is used for other purposes and they can conflict.

In particular master->mutex is held while w1_attach_slave_device is
called.

For bq27000, this registers a 'powersupply' device which tries to read the
current status.  The attempt to read will cause a deadlock on
master->mutex.

So create a new per-slave mutex and use that for serializing IO for
bq27000.

Signed-off-by: NeilBrown <neilb@suse.de>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
NeilBrown 2012-05-01 11:49:24 -07:00 committed by Greg Kroah-Hartman
parent bdd4034df8
commit 59d4467be4
3 changed files with 4 additions and 2 deletions

View File

@ -31,10 +31,10 @@ static int w1_bq27000_read(struct device *dev, unsigned int reg)
u8 val;
struct w1_slave *sl = container_of(dev->parent, struct w1_slave, dev);
mutex_lock(&sl->master->mutex);
mutex_lock(&sl->mutex);
w1_write_8(sl->master, HDQ_CMD_READ | reg);
val = w1_read_8(sl->master);
mutex_unlock(&sl->master->mutex);
mutex_unlock(&sl->mutex);
return val;
}

View File

@ -688,6 +688,7 @@ static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
atomic_set(&sl->refcnt, 0);
init_completion(&sl->released);
mutex_init(&sl->mutex);
spin_lock(&w1_flock);
f = w1_family_registered(rn->family);

View File

@ -75,6 +75,7 @@ struct w1_slave
void *family_data;
struct device dev;
struct completion released;
struct mutex mutex;
};
typedef void (*w1_slave_found_callback)(struct w1_master *, u64);