summaryrefslogtreecommitdiff
path: root/drivers/hwtracing/stm
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/hwtracing/stm')
-rw-r--r--drivers/hwtracing/stm/Kconfig4
-rw-r--r--drivers/hwtracing/stm/core.c148
-rw-r--r--drivers/hwtracing/stm/policy.c25
-rw-r--r--drivers/hwtracing/stm/stm.h2
4 files changed, 139 insertions, 40 deletions
diff --git a/drivers/hwtracing/stm/Kconfig b/drivers/hwtracing/stm/Kconfig
index e7a348807f0c..e0ac75395526 100644
--- a/drivers/hwtracing/stm/Kconfig
+++ b/drivers/hwtracing/stm/Kconfig
@@ -9,6 +9,8 @@ config STM
Say Y here to enable System Trace Module device support.
+if STM
+
config STM_DUMMY
tristate "Dummy STM driver"
help
@@ -25,3 +27,5 @@ config STM_SOURCE_CONSOLE
If you want to send kernel console messages over STM devices,
say Y.
+
+endif
diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index 92ab51aa8a74..b6cc841de79d 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -114,6 +114,7 @@ struct stm_device *stm_find_device(const char *buf)
stm = to_stm_device(dev);
if (!try_module_get(stm->owner)) {
+ /* matches class_find_device() above */
put_device(dev);
return NULL;
}
@@ -126,7 +127,7 @@ struct stm_device *stm_find_device(const char *buf)
* @stm: stm device, previously acquired by stm_find_device()
*
* This drops the module reference and device reference taken by
- * stm_find_device().
+ * stm_find_device() or stm_char_open().
*/
void stm_put_device(struct stm_device *stm)
{
@@ -186,6 +187,9 @@ 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;
@@ -200,6 +204,9 @@ 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));
@@ -292,6 +299,7 @@ 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;
@@ -308,6 +316,7 @@ 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;
@@ -316,11 +325,18 @@ 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;
@@ -343,6 +359,7 @@ 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))
@@ -353,6 +370,8 @@ static int stm_char_open(struct inode *inode, struct file *file)
return nonseekable_open(inode, file);
err_free:
+ /* matches class_find_device() above */
+ put_device(dev);
kfree(stmf);
return err;
@@ -363,6 +382,11 @@ static int stm_char_release(struct inode *inode, struct file *file)
struct stm_file *stmf = file->private_data;
stm_output_free(stmf->stm, &stmf->output);
+
+ /*
+ * matches the stm_char_open()'s
+ * class_find_device() + try_module_get()
+ */
stm_put_device(stmf->stm);
kfree(stmf);
@@ -410,6 +434,9 @@ static ssize_t stm_char_write(struct file *file, const char __user *buf,
char *kbuf;
int err;
+ if (count + 1 > PAGE_SIZE)
+ count = PAGE_SIZE - 1;
+
/*
* if no m/c have been assigned to this writer up to this
* point, use "default" policy entry
@@ -521,10 +548,8 @@ static int stm_char_policy_set_ioctl(struct stm_file *stmf, void __user *arg)
ret = stm->data->link(stm->data, stmf->output.master,
stmf->output.channel);
- if (ret) {
+ if (ret)
stm_output_free(stmf->stm, &stmf->output);
- stm_put_device(stmf->stm);
- }
err_free:
kfree(id);
@@ -639,17 +664,11 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data,
stm->dev.parent = parent;
stm->dev.release = stm_device_release;
- err = kobject_set_name(&stm->dev.kobj, "%s", stm_data->name);
- if (err)
- goto err_device;
-
- err = device_add(&stm->dev);
- if (err)
- goto err_device;
-
+ mutex_init(&stm->link_mutex);
spin_lock_init(&stm->link_lock);
INIT_LIST_HEAD(&stm->link_list);
+ /* initialize the object before it is accessible via sysfs */
spin_lock_init(&stm->mc_lock);
mutex_init(&stm->policy_mutex);
stm->sw_nmasters = nmasters;
@@ -657,9 +676,20 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data,
stm->data = stm_data;
stm_data->stm = stm;
+ err = kobject_set_name(&stm->dev.kobj, "%s", stm_data->name);
+ if (err)
+ goto err_device;
+
+ err = device_add(&stm->dev);
+ if (err)
+ goto err_device;
+
return 0;
err_device:
+ unregister_chrdev(stm->major, stm_data->name);
+
+ /* matches device_initialize() above */
put_device(&stm->dev);
err_free:
vfree(stm);
@@ -668,20 +698,28 @@ err_free:
}
EXPORT_SYMBOL_GPL(stm_register_device);
-static void __stm_source_link_drop(struct stm_source_device *src,
- struct stm_device *stm);
+static int __stm_source_link_drop(struct stm_source_device *src,
+ struct stm_device *stm);
void stm_unregister_device(struct stm_data *stm_data)
{
struct stm_device *stm = stm_data->stm;
struct stm_source_device *src, *iter;
- int i;
+ int i, ret;
- spin_lock(&stm->link_lock);
+ mutex_lock(&stm->link_mutex);
list_for_each_entry_safe(src, iter, &stm->link_list, link_entry) {
- __stm_source_link_drop(src, stm);
+ ret = __stm_source_link_drop(src, stm);
+ /*
+ * src <-> stm link must not change under the same
+ * stm::link_mutex, so complain loudly if it has;
+ * also in this situation ret!=0 means this src is
+ * not connected to this stm and it should be otherwise
+ * safe to proceed with the tear-down of stm.
+ */
+ WARN_ON_ONCE(ret);
}
- spin_unlock(&stm->link_lock);
+ mutex_unlock(&stm->link_mutex);
synchronize_srcu(&stm_source_srcu);
@@ -700,6 +738,17 @@ void stm_unregister_device(struct stm_data *stm_data)
}
EXPORT_SYMBOL_GPL(stm_unregister_device);
+/*
+ * stm::link_list access serialization uses a spinlock and a mutex; holding
+ * either of them guarantees that the list is stable; modification requires
+ * holding both of them.
+ *
+ * Lock ordering is as follows:
+ * stm::link_mutex
+ * stm::link_lock
+ * src::link_lock
+ */
+
/**
* stm_source_link_add() - connect an stm_source device to an stm device
* @src: stm_source device
@@ -716,6 +765,7 @@ static int stm_source_link_add(struct stm_source_device *src,
char *id;
int err;
+ mutex_lock(&stm->link_mutex);
spin_lock(&stm->link_lock);
spin_lock(&src->link_lock);
@@ -725,6 +775,7 @@ static int stm_source_link_add(struct stm_source_device *src,
spin_unlock(&src->link_lock);
spin_unlock(&stm->link_lock);
+ mutex_unlock(&stm->link_mutex);
id = kstrdup(src->data->name, GFP_KERNEL);
if (id) {
@@ -759,9 +810,9 @@ static int stm_source_link_add(struct stm_source_device *src,
fail_free_output:
stm_output_free(stm, &src->output);
- stm_put_device(stm);
fail_detach:
+ mutex_lock(&stm->link_mutex);
spin_lock(&stm->link_lock);
spin_lock(&src->link_lock);
@@ -770,6 +821,7 @@ fail_detach:
spin_unlock(&src->link_lock);
spin_unlock(&stm->link_lock);
+ mutex_unlock(&stm->link_mutex);
return err;
}
@@ -782,28 +834,45 @@ fail_detach:
* If @stm is @src::link, disconnect them from one another and put the
* reference on the @stm device.
*
- * Caller must hold stm::link_lock.
+ * Caller must hold stm::link_mutex.
*/
-static void __stm_source_link_drop(struct stm_source_device *src,
- struct stm_device *stm)
+static int __stm_source_link_drop(struct stm_source_device *src,
+ struct stm_device *stm)
{
struct stm_device *link;
+ int ret = 0;
+ lockdep_assert_held(&stm->link_mutex);
+
+ /* for stm::link_list modification, we hold both mutex and spinlock */
+ spin_lock(&stm->link_lock);
spin_lock(&src->link_lock);
link = srcu_dereference_check(src->link, &stm_source_srcu, 1);
- if (WARN_ON_ONCE(link != stm)) {
- spin_unlock(&src->link_lock);
- return;
+
+ /*
+ * The linked device may have changed since we last looked, because
+ * we weren't holding the src::link_lock back then; if this is the
+ * case, tell the caller to retry.
+ */
+ if (link != stm) {
+ ret = -EAGAIN;
+ goto unlock;
}
stm_output_free(link, &src->output);
- /* caller must hold stm::link_lock */
list_del_init(&src->link_entry);
/* matches stm_find_device() from stm_source_link_store() */
stm_put_device(link);
rcu_assign_pointer(src->link, NULL);
+unlock:
spin_unlock(&src->link_lock);
+ spin_unlock(&stm->link_lock);
+
+ if (!ret && src->data->unlink)
+ src->data->unlink(src->data);
+
+ return ret;
}
/**
@@ -819,21 +888,29 @@ static void __stm_source_link_drop(struct stm_source_device *src,
static void stm_source_link_drop(struct stm_source_device *src)
{
struct stm_device *stm;
- int idx;
+ int idx, ret;
+retry:
idx = srcu_read_lock(&stm_source_srcu);
+ /*
+ * The stm device will be valid for the duration of this
+ * read section, but the link may change before we grab
+ * the src::link_lock in __stm_source_link_drop().
+ */
stm = srcu_dereference(src->link, &stm_source_srcu);
+ ret = 0;
if (stm) {
- if (src->data->unlink)
- src->data->unlink(src->data);
-
- spin_lock(&stm->link_lock);
- __stm_source_link_drop(src, stm);
- spin_unlock(&stm->link_lock);
+ mutex_lock(&stm->link_mutex);
+ ret = __stm_source_link_drop(src, stm);
+ mutex_unlock(&stm->link_mutex);
}
srcu_read_unlock(&stm_source_srcu, idx);
+
+ /* if it did change, retry */
+ if (ret == -EAGAIN)
+ goto retry;
}
static ssize_t stm_source_link_show(struct device *dev,
@@ -868,8 +945,10 @@ static ssize_t stm_source_link_store(struct device *dev,
return -EINVAL;
err = stm_source_link_add(src, link);
- if (err)
+ if (err) {
+ /* matches the stm_find_device() above */
stm_put_device(link);
+ }
return err ? : count;
}
@@ -931,6 +1010,7 @@ 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/policy.c b/drivers/hwtracing/stm/policy.c
index 11ab6d01adf6..1db189657b2b 100644
--- a/drivers/hwtracing/stm/policy.c
+++ b/drivers/hwtracing/stm/policy.c
@@ -272,13 +272,17 @@ void stp_policy_unbind(struct stp_policy *policy)
{
struct stm_device *stm = policy->stm;
+ /*
+ * stp_policy_release() will not call here if the policy is already
+ * unbound; other users should not either, as no link exists between
+ * this policy and anything else in that case
+ */
if (WARN_ON_ONCE(!policy->stm))
return;
- mutex_lock(&stm->policy_mutex);
- stm->policy = NULL;
- mutex_unlock(&stm->policy_mutex);
+ lockdep_assert_held(&stm->policy_mutex);
+ stm->policy = NULL;
policy->stm = NULL;
stm_put_device(stm);
@@ -287,8 +291,16 @@ void stp_policy_unbind(struct stp_policy *policy)
static void stp_policy_release(struct config_item *item)
{
struct stp_policy *policy = to_stp_policy(item);
+ struct stm_device *stm = policy->stm;
+ /* a policy *can* be unbound and still exist in configfs tree */
+ if (!stm)
+ return;
+
+ mutex_lock(&stm->policy_mutex);
stp_policy_unbind(policy);
+ mutex_unlock(&stm->policy_mutex);
+
kfree(policy);
}
@@ -320,10 +332,11 @@ stp_policies_make(struct config_group *group, const char *name)
/*
* node must look like <device_name>.<policy_name>, where
- * <device_name> is the name of an existing stm device and
- * <policy_name> is an arbitrary string
+ * <device_name> is the name of an existing stm device; may
+ * contain dots;
+ * <policy_name> is an arbitrary string; may not contain dots
*/
- p = strchr(devname, '.');
+ p = strrchr(devname, '.');
if (!p) {
kfree(devname);
return ERR_PTR(-EINVAL);
diff --git a/drivers/hwtracing/stm/stm.h b/drivers/hwtracing/stm/stm.h
index 95ece0292c99..4e8c6926260f 100644
--- a/drivers/hwtracing/stm/stm.h
+++ b/drivers/hwtracing/stm/stm.h
@@ -45,6 +45,7 @@ struct stm_device {
int major;
unsigned int sw_nmasters;
struct stm_data *data;
+ struct mutex link_mutex;
spinlock_t link_lock;
struct list_head link_list;
/* master allocation */
@@ -56,6 +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;
generated by cgit v1.2.3 (git 2.39.1) at 2024-10-17 21:42:06 +0000