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| author | NeilBrown <neilb@suse.de> | 2012-05-01 11:49:24 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-06-12 15:27:32 -0700 |
| commit | 59d4467be405316916a4087d5b02d99196eeef04 (patch) | |
| tree | c6f42a454b2d3e3818c84bb0050a2f920993b1df /drivers | |
| parent | bdd4034df8b37841eeaf7b05f86e732ab8e0b08a (diff) | |
| download | linux-stable-59d4467be405316916a4087d5b02d99196eeef04.tar.gz linux-stable-59d4467be405316916a4087d5b02d99196eeef04.tar.bz2 linux-stable-59d4467be405316916a4087d5b02d99196eeef04.zip | |
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')
| -rw-r--r-- | drivers/w1/slaves/w1_bq27000.c | 4 | ||||
| -rw-r--r-- | drivers/w1/w1.c | 1 | ||||
| -rw-r--r-- | drivers/w1/w1.h | 1 |
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); |