diff options
author | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2016-06-10 05:30:17 -0300 |
---|---|---|
committer | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2016-06-10 05:30:17 -0300 |
commit | d635711daa98be86d4c7fd01499c34f566b54ccb (patch) | |
tree | aa5cc3760a27c3d57146498cb82fa549547de06c /drivers/hwtracing/stm/core.c | |
parent | c91265cd0efb83778f015b4d4b1129bd2cfd075e (diff) |
Linux-libre 4.6.2-gnu
Diffstat (limited to 'drivers/hwtracing/stm/core.c')
-rw-r--r-- | drivers/hwtracing/stm/core.c | 175 |
1 files changed, 136 insertions, 39 deletions
diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c index b6445d9e5..de80d45d8 100644 --- a/drivers/hwtracing/stm/core.c +++ b/drivers/hwtracing/stm/core.c @@ -113,6 +113,7 @@ 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; } @@ -125,7 +126,7 @@ 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) { @@ -185,6 +186,9 @@ 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 +203,9 @@ 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)); @@ -233,7 +240,7 @@ static int find_free_channels(unsigned long *bitmap, unsigned int start, return -1; } -static unsigned int +static int stm_find_master_chan(struct stm_device *stm, unsigned int width, unsigned int *mstart, unsigned int mend, unsigned int *cstart, unsigned int cend) @@ -288,12 +295,13 @@ 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; ret = stm_find_master_chan(stm, width, &midx, mend, &cidx, cend); - if (ret) + if (ret < 0) goto unlock; output->master = midx; @@ -304,6 +312,7 @@ 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 +321,18 @@ 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 +355,7 @@ 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)) @@ -349,6 +366,8 @@ 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; @@ -357,9 +376,19 @@ err_free: static int stm_char_release(struct inode *inode, struct file *file) { struct stm_file *stmf = file->private_data; + struct stm_device *stm = stmf->stm; + + if (stm->data->unlink) + stm->data->unlink(stm->data, stmf->output.master, + stmf->output.channel); - stm_output_free(stmf->stm, &stmf->output); - stm_put_device(stmf->stm); + stm_output_free(stm, &stmf->output); + + /* + * matches the stm_char_open()'s + * class_find_device() + try_module_get() + */ + stm_put_device(stm); kfree(stmf); return 0; @@ -380,8 +409,8 @@ static int stm_file_assign(struct stm_file *stmf, char *id, unsigned int width) return ret; } -static void stm_write(struct stm_data *data, unsigned int master, - unsigned int channel, const char *buf, size_t count) +static ssize_t stm_write(struct stm_data *data, unsigned int master, + unsigned int channel, const char *buf, size_t count) { unsigned int flags = STP_PACKET_TIMESTAMPED; const unsigned char *p = buf, nil = 0; @@ -393,9 +422,14 @@ static void stm_write(struct stm_data *data, unsigned int master, sz = data->packet(data, master, channel, STP_PACKET_DATA, flags, sz, p); flags = 0; + + if (sz < 0) + break; } data->packet(data, master, channel, STP_PACKET_FLAG, 0, 0, &nil); + + return pos; } static ssize_t stm_char_write(struct file *file, const char __user *buf, @@ -406,6 +440,9 @@ 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 @@ -430,8 +467,8 @@ static ssize_t stm_char_write(struct file *file, const char __user *buf, return -EFAULT; } - stm_write(stm->data, stmf->output.master, stmf->output.channel, kbuf, - count); + count = stm_write(stm->data, stmf->output.master, stmf->output.channel, + kbuf, count); kfree(kbuf); @@ -515,10 +552,8 @@ 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); @@ -618,7 +653,7 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data, if (!stm_data->packet || !stm_data->sw_nchannels) return -EINVAL; - nmasters = stm_data->sw_end - stm_data->sw_start; + nmasters = stm_data->sw_end - stm_data->sw_start + 1; stm = kzalloc(sizeof(*stm) + nmasters * sizeof(void *), GFP_KERNEL); if (!stm) return -ENOMEM; @@ -641,6 +676,7 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data, if (err) goto err_device; + mutex_init(&stm->link_mutex); spin_lock_init(&stm->link_lock); INIT_LIST_HEAD(&stm->link_list); @@ -654,6 +690,7 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data, return 0; err_device: + /* matches device_initialize() above */ put_device(&stm->dev); err_free: kfree(stm); @@ -662,20 +699,28 @@ 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); @@ -686,7 +731,7 @@ void stm_unregister_device(struct stm_data *stm_data) stp_policy_unbind(stm->policy); mutex_unlock(&stm->policy_mutex); - for (i = 0; i < stm->sw_nmasters; i++) + for (i = stm->data->sw_start; i <= stm->data->sw_end; i++) stp_master_free(stm, i); device_unregister(&stm->dev); @@ -694,6 +739,17 @@ 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 @@ -710,6 +766,7 @@ 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); @@ -719,6 +776,7 @@ 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) { @@ -753,9 +811,9 @@ 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); @@ -764,6 +822,7 @@ fail_detach: spin_unlock(&src->link_lock); spin_unlock(&stm->link_lock); + mutex_unlock(&stm->link_mutex); return err; } @@ -776,28 +835,55 @@ 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); + + /* + * Call the unlink callbacks for both source and stm, when we know + * that we have actually performed the unlinking. + */ + if (!ret) { + if (src->data->unlink) + src->data->unlink(src->data); + + if (stm->data->unlink) + stm->data->unlink(stm->data, src->output.master, + src->output.channel); + } + + return ret; } /** @@ -813,21 +899,29 @@ 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, @@ -862,8 +956,10 @@ 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; } @@ -925,6 +1021,7 @@ 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; @@ -973,9 +1070,9 @@ int stm_source_write(struct stm_source_data *data, unsigned int chan, stm = srcu_dereference(src->link, &stm_source_srcu); if (stm) - stm_write(stm->data, src->output.master, - src->output.channel + chan, - buf, count); + count = stm_write(stm->data, src->output.master, + src->output.channel + chan, + buf, count); else count = -ENODEV; |