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authorNeilBrown <neilb@suse.de>2012-05-01 11:49:24 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-06-12 15:27:32 -0700
commit59d4467be405316916a4087d5b02d99196eeef04 (patch)
treec6f42a454b2d3e3818c84bb0050a2f920993b1df /drivers/w1
parentbdd4034df8b37841eeaf7b05f86e732ab8e0b08a (diff)
downloadlinux-59d4467be405316916a4087d5b02d99196eeef04.tar.bz2
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>
Diffstat (limited to 'drivers/w1')
-rw-r--r--drivers/w1/slaves/w1_bq27000.c4
-rw-r--r--drivers/w1/w1.c1
-rw-r--r--drivers/w1/w1.h1
3 files changed, 4 insertions, 2 deletions
diff --git a/drivers/w1/slaves/w1_bq27000.c b/drivers/w1/slaves/w1_bq27000.c
index 52ad812fa1e7..87554788fa32 100644
--- a/drivers/w1/slaves/w1_bq27000.c
+++ b/drivers/w1/slaves/w1_bq27000.c
@@ -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;
}
diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index 2f2e894ea0c8..69075c3dfc73 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -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);
diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h
index 4d012ca3f32c..8c8be380a98a 100644
--- a/drivers/w1/w1.h
+++ b/drivers/w1/w1.h
@@ -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);