stm class: Guard output assignment against concurrency
It is possible to concurrently assign the same output (a character device writer or an stm_source device) to different stm devices, which sets off a strategically placed warning in stm_output_assign(). To avoid this, use a spinlock to serialize (un)assignments between outputs and stm devices. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -185,6 +185,9 @@ static void stm_output_claim(struct stm_device *stm, struct stm_output *output)
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{
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{
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struct stp_master *master = stm_master(stm, output->master);
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struct stp_master *master = stm_master(stm, output->master);
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lockdep_assert_held(&stm->mc_lock);
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lockdep_assert_held(&output->lock);
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if (WARN_ON_ONCE(master->nr_free < output->nr_chans))
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if (WARN_ON_ONCE(master->nr_free < output->nr_chans))
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return;
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return;
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@ -199,6 +202,9 @@ stm_output_disclaim(struct stm_device *stm, struct stm_output *output)
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{
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{
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struct stp_master *master = stm_master(stm, output->master);
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struct stp_master *master = stm_master(stm, output->master);
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lockdep_assert_held(&stm->mc_lock);
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lockdep_assert_held(&output->lock);
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bitmap_release_region(&master->chan_map[0], output->channel,
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bitmap_release_region(&master->chan_map[0], output->channel,
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ilog2(output->nr_chans));
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ilog2(output->nr_chans));
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@ -288,6 +294,7 @@ static int stm_output_assign(struct stm_device *stm, unsigned int width,
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}
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}
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spin_lock(&stm->mc_lock);
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spin_lock(&stm->mc_lock);
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spin_lock(&output->lock);
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/* output is already assigned -- shouldn't happen */
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/* output is already assigned -- shouldn't happen */
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if (WARN_ON_ONCE(output->nr_chans))
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if (WARN_ON_ONCE(output->nr_chans))
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goto unlock;
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goto unlock;
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@ -304,6 +311,7 @@ static int stm_output_assign(struct stm_device *stm, unsigned int width,
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ret = 0;
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ret = 0;
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unlock:
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unlock:
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spin_unlock(&output->lock);
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spin_unlock(&stm->mc_lock);
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spin_unlock(&stm->mc_lock);
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return ret;
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return ret;
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@ -312,11 +320,18 @@ static int stm_output_assign(struct stm_device *stm, unsigned int width,
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static void stm_output_free(struct stm_device *stm, struct stm_output *output)
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static void stm_output_free(struct stm_device *stm, struct stm_output *output)
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{
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{
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spin_lock(&stm->mc_lock);
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spin_lock(&stm->mc_lock);
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spin_lock(&output->lock);
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if (output->nr_chans)
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if (output->nr_chans)
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stm_output_disclaim(stm, output);
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stm_output_disclaim(stm, output);
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spin_unlock(&output->lock);
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spin_unlock(&stm->mc_lock);
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spin_unlock(&stm->mc_lock);
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}
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}
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static void stm_output_init(struct stm_output *output)
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{
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spin_lock_init(&output->lock);
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}
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static int major_match(struct device *dev, const void *data)
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static int major_match(struct device *dev, const void *data)
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{
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{
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unsigned int major = *(unsigned int *)data;
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unsigned int major = *(unsigned int *)data;
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@ -339,6 +354,7 @@ static int stm_char_open(struct inode *inode, struct file *file)
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if (!stmf)
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if (!stmf)
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return -ENOMEM;
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return -ENOMEM;
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stm_output_init(&stmf->output);
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stmf->stm = to_stm_device(dev);
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stmf->stm = to_stm_device(dev);
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if (!try_module_get(stmf->stm->owner))
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if (!try_module_get(stmf->stm->owner))
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@ -952,6 +968,7 @@ int stm_source_register_device(struct device *parent,
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if (err)
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if (err)
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goto err;
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goto err;
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stm_output_init(&src->output);
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spin_lock_init(&src->link_lock);
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spin_lock_init(&src->link_lock);
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INIT_LIST_HEAD(&src->link_entry);
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INIT_LIST_HEAD(&src->link_entry);
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src->data = data;
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src->data = data;
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@ -57,6 +57,7 @@ struct stm_device {
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container_of((_d), struct stm_device, dev)
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container_of((_d), struct stm_device, dev)
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struct stm_output {
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struct stm_output {
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spinlock_t lock;
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unsigned int master;
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unsigned int master;
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unsigned int channel;
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unsigned int channel;
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unsigned int nr_chans;
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unsigned int nr_chans;
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