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Commit 59d4467b authored by NeilBrown's avatar NeilBrown Committed by Greg Kroah-Hartman
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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: default avatarNeilBrown <neilb@suse.de>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent bdd4034d

drivers/w1/slaves/w1_bq27000.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

}

drivers/w1/w1.c

+1 −0
Original line number Diff line number Diff line
@@ -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);

drivers/w1/w1.h

+1 −0
Original line number Diff line number Diff line
@@ -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);