w1: introduce a slave mutex for serializing IO (59d4467b) · Commits · 戴 / test

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>

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);

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