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>
diff --git a/drivers/w1/slaves/w1_bq27000.c b/drivers/w1/slaves/w1_bq27000.c
index 52ad812..8755478 100644
--- a/drivers/w1/slaves/w1_bq27000.c
+++ b/drivers/w1/slaves/w1_bq27000.c
@@ -31,10 +31,10 @@
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;
}
diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index 2f2e894..69075c3 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -688,6 +688,7 @@
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);
diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h
index 4d012ca..8c8be38 100644
--- a/drivers/w1/w1.h
+++ b/drivers/w1/w1.h
@@ -75,6 +75,7 @@
void *family_data;
struct device dev;
struct completion released;
+ struct mutex mutex;
};
typedef void (*w1_slave_found_callback)(struct w1_master *, u64);