Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1332946
| From | Alexander Shishkin <alexander.shishkin@linux.intel.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [QUEUED v20160212 15/19] stm class: Guard output assignment against concurrency |
| Date | 2016-02-12 18:20 +0100 |
| Message-ID | <r1pxW-1vA-47@gated-at.bofh.it> (permalink) |
| References | <r1poe-1rA-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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>
---
drivers/hwtracing/stm/core.c | 17 +++++++++++++++++
drivers/hwtracing/stm/stm.h | 1 +
2 files changed, 18 insertions(+)
diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index fb5a6a582b..6a254ce4b9 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 97ee022414..4e8c692626 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;
--
2.7.0
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[QUEUED v20160212 00/19] stm class/intel_th: Patches in my queue Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:10 +0100 [QUEUED v20160212 01/19] stm class: Use a signed return type for stm_find_master_chan Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:10 +0100 [QUEUED v20160212 04/19] intel_th: Update scratchpad bits according to enabled output activity Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:10 +0100 [QUEUED v20160212 02/19] intel_th: Depend on HAS_IOMEM Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:10 +0100 [QUEUED v20160212 07/19] intel_th: sth: Sanitize packet callback's return values Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:10 +0100 [QUEUED v20160212 08/19] intel_th: Set root device's drvdata early Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:10 +0100 [QUEUED v20160212 11/19] stm class: Support devices with multiple instances Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:10 +0100 [QUEUED v20160212 03/19] intel_th: gth: Remove commented-out code Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:10 +0100 [QUEUED v20160212 18/19] stm class: Plug stm device's unlink callback Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:20 +0100 [QUEUED v20160212 16/19] stm class: Fix unbalanced module/device refcounting Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:20 +0100 [QUEUED v20160212 19/19] stm class: dummy_stm: Add link callback for fault injection Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:20 +0100 [QUEUED v20160212 12/19] stm class: dummy_stm: Create multiple devices Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:20 +0100 [QUEUED v20160212 17/19] stm class: Fix a race in unlinking Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:20 +0100 [QUEUED v20160212 15/19] stm class: Guard output assignment against concurrency Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:20 +0100 [QUEUED v20160212 14/19] stm class: Fix unlocking braino in the error path Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:20 +0100 [QUEUED v20160212 13/19] stm class: Add heartbeat stm source device Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-12 18:20 +0100
csiph-web