diff options
| author | Alexander Shishkin <alexander.shishkin@linux.intel.com> | 2016-02-15 18:12:06 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-02-20 23:09:14 +0100 |
| commit | cde4ad8368840e414ecf67db258fe1dabaa5fd2e (patch) | |
| tree | 17f5dee33891f9b3aed3e10709a36d285c59b892 /drivers/hwtracing | |
| parent | stm class: Fix unlocking braino in the error path (diff) | |
| download | linux-cde4ad8368840e414ecf67db258fe1dabaa5fd2e.tar.xz linux-cde4ad8368840e414ecf67db258fe1dabaa5fd2e.zip | |
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>
Diffstat (limited to 'drivers/hwtracing')
| -rw-r--r-- | drivers/hwtracing/stm/core.c | 17 | ||||
| -rw-r--r-- | drivers/hwtracing/stm/stm.h | 1 |
2 files changed, 18 insertions, 0 deletions
diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c index 4a626d8990b2..f6ade21729fa 100644 --- a/drivers/hwtracing/stm/core.c +++ b/drivers/hwtracing/stm/core.c @@ -185,6 +185,9 @@ static void stm_output_claim(struct stm_device *stm, struct stm_output *output) { struct stp_master *master = stm_master(stm, output->master); + lockdep_assert_held(&stm->mc_lock); + lockdep_assert_held(&output->lock); + if (WARN_ON_ONCE(master->nr_free < output->nr_chans)) return; @@ -199,6 +202,9 @@ stm_output_disclaim(struct stm_device *stm, struct stm_output *output) { struct stp_master *master = stm_master(stm, output->master); + lockdep_assert_held(&stm->mc_lock); + lockdep_assert_held(&output->lock); + bitmap_release_region(&master->chan_map[0], output->channel, ilog2(output->nr_chans)); @@ -288,6 +294,7 @@ static int stm_output_assign(struct stm_device *stm, unsigned int width, } spin_lock(&stm->mc_lock); + spin_lock(&output->lock); /* output is already assigned -- shouldn't happen */ if (WARN_ON_ONCE(output->nr_chans)) goto unlock; @@ -304,6 +311,7 @@ static int stm_output_assign(struct stm_device *stm, unsigned int width, ret = 0; unlock: + spin_unlock(&output->lock); spin_unlock(&stm->mc_lock); return ret; @@ -312,11 +320,18 @@ unlock: static void stm_output_free(struct stm_device *stm, struct stm_output *output) { spin_lock(&stm->mc_lock); + spin_lock(&output->lock); if (output->nr_chans) stm_output_disclaim(stm, output); + spin_unlock(&output->lock); spin_unlock(&stm->mc_lock); } +static void stm_output_init(struct stm_output *output) +{ + spin_lock_init(&output->lock); +} + static int major_match(struct device *dev, const void *data) { unsigned int major = *(unsigned int *)data; @@ -339,6 +354,7 @@ static int stm_char_open(struct inode *inode, struct file *file) if (!stmf) return -ENOMEM; + stm_output_init(&stmf->output); stmf->stm = to_stm_device(dev); if (!try_module_get(stmf->stm->owner)) @@ -952,6 +968,7 @@ int stm_source_register_device(struct device *parent, if (err) goto err; + stm_output_init(&src->output); spin_lock_init(&src->link_lock); INIT_LIST_HEAD(&src->link_entry); src->data = data; diff --git a/drivers/hwtracing/stm/stm.h b/drivers/hwtracing/stm/stm.h index 97ee02241440..4e8c6926260f 100644 --- a/drivers/hwtracing/stm/stm.h +++ b/drivers/hwtracing/stm/stm.h @@ -57,6 +57,7 @@ struct stm_device { container_of((_d), struct stm_device, dev) struct stm_output { + spinlock_t lock; unsigned int master; unsigned int channel; unsigned int nr_chans; |