Messages in this thread Patch in this message | | | Date | Wed, 25 Apr 2012 12:49:14 +1000 | From | NeilBrown <> | Subject | [PATCH] w1: Introduce a slave mutex for serializing IO. |
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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> --- drivers/w1/slaves/w1_bq27000.c | 4 ++-- drivers/w1/w1.c | 1 + 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 52ad812..8755478 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 9761950..2173f83 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 4d012ca..8c8be38 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); -- 1.7.10 [unhandled content-type:application/pgp-signature]
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