Keep reference count on transport and file ops modules

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/lib/ringbuffer/ring_buffer_iterator.c b/lib/ringbuffer/ring_buffer_iterator.c
index df8d485ab92af72953049a115b0ac074a038aebb..1321b5f965a95bfefd0e0a5ada6ad6fa4fa759ea 100644 (file)
--- a/lib/ringbuffer/ring_buffer_iterator.c
+++ b/lib/ringbuffer/ring_buffer_iterator.c
@@ -780,6 +780,7 @@ int channel_file_release(struct inode *inode, struct file *file)
 }
 
 const struct file_operations channel_payload_file_operations = {
+       .owner = THIS_MODULE,
        .open = channel_file_open,
        .release = channel_file_release,
        .read = channel_file_read,
@@ -788,6 +789,7 @@ const struct file_operations channel_payload_file_operations = {
 EXPORT_SYMBOL_GPL(channel_payload_file_operations);
 
 const struct file_operations lib_ring_buffer_payload_file_operations = {
+       .owner = THIS_MODULE,
        .open = lib_ring_buffer_file_open,
        .release = lib_ring_buffer_file_release,
        .read = lib_ring_buffer_file_read,

diff --git a/lib/ringbuffer/ring_buffer_vfs.c b/lib/ringbuffer/ring_buffer_vfs.c
index 60d69a929b816a8c0db1a0216688b6e73fb527d2..1708ffd6bc9b1b80f06da11af5cb7830c2a6923b 100644 (file)
--- a/lib/ringbuffer/ring_buffer_vfs.c
+++ b/lib/ringbuffer/ring_buffer_vfs.c
@@ -368,6 +368,7 @@ long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 #endif
 
 const struct file_operations lib_ring_buffer_file_operations = {
+       .owner = THIS_MODULE,
        .open = lib_ring_buffer_open,
        .release = lib_ring_buffer_release,
        .poll = lib_ring_buffer_poll,

diff --git a/ltt-debugfs-abi.c b/ltt-debugfs-abi.c
index 72077183aaa5c01acc48a85a0e3aeaa527e85363..cfc364a844635f1476a17e7e7c794b73478f6017 100644 (file)
--- a/ltt-debugfs-abi.c
+++ b/ltt-debugfs-abi.c
@@ -49,6 +49,11 @@ static const struct file_operations lttng_channel_fops;
 static const struct file_operations lttng_metadata_fops;
 static const struct file_operations lttng_event_fops;
 
+/*
+ * Teardown management: opened file descriptors keep a refcount on the module,
+ * so it can only exit when all file descriptors are closed.
+ */
+
 enum channel_type {
        PER_CPU_CHANNEL,
        METADATA_CHANNEL,
@@ -221,6 +226,7 @@ long lttng_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 }
 
 static const struct file_operations lttng_fops = {
+       .owner = THIS_MODULE,
        .unlocked_ioctl = lttng_ioctl,
 #ifdef CONFIG_COMPAT
        .compat_ioctl = lttng_ioctl,
@@ -410,6 +416,7 @@ int lttng_session_release(struct inode *inode, struct file *file)
 }
 
 static const struct file_operations lttng_session_fops = {
+       .owner = THIS_MODULE,
        .release = lttng_session_release,
        .unlocked_ioctl = lttng_session_ioctl,
 #ifdef CONFIG_COMPAT
@@ -628,6 +635,7 @@ int lttng_channel_release(struct inode *inode, struct file *file)
 }
 
 static const struct file_operations lttng_channel_fops = {
+       .owner = THIS_MODULE,
        .release = lttng_channel_release,
        .poll = lttng_channel_poll,
        .unlocked_ioctl = lttng_channel_ioctl,
@@ -637,6 +645,7 @@ static const struct file_operations lttng_channel_fops = {
 };
 
 static const struct file_operations lttng_metadata_fops = {
+       .owner = THIS_MODULE,
        .release = lttng_channel_release,
        .unlocked_ioctl = lttng_metadata_ioctl,
 #ifdef CONFIG_COMPAT
@@ -690,6 +699,7 @@ int lttng_event_release(struct inode *inode, struct file *file)
 
 /* TODO: filter control ioctl */
 static const struct file_operations lttng_event_fops = {
+       .owner = THIS_MODULE,
        .release = lttng_event_release,
        .unlocked_ioctl = lttng_event_ioctl,
 #ifdef CONFIG_COMPAT

diff --git a/ltt-events.c b/ltt-events.c
index e9e076d802238bc07e1aef14e0bb4f1e2914df6b..3532dee5a1c8d46e246fa14c8e6c07a1257f26c7 100644 (file)
--- a/ltt-events.c
+++ b/ltt-events.c
@@ -196,7 +196,7 @@ struct ltt_channel *ltt_channel_create(struct ltt_session *session,
                                       unsigned int read_timer_interval)
 {
        struct ltt_channel *chan;
-       struct ltt_transport *transport;
+       struct ltt_transport *transport = NULL;
 
        mutex_lock(&sessions_mutex);
        if (session->been_active)
@@ -207,6 +207,10 @@ struct ltt_channel *ltt_channel_create(struct ltt_session *session,
                       transport_name);
                goto notransport;
        }
+       if (!try_module_get(transport->owner)) {
+               printk(KERN_WARNING "LTT : Can't lock transport module.\n");
+               goto notransport;
+       }
        chan = kzalloc(sizeof(struct ltt_channel), GFP_KERNEL);
        if (!chan)
                goto nomem;
@@ -224,6 +228,7 @@ struct ltt_channel *ltt_channel_create(struct ltt_session *session,
                goto create_error;
        chan->enabled = 1;
        chan->ops = &transport->ops;
+       chan->transport = transport;
        list_add(&chan->list, &session->chan);
        mutex_unlock(&sessions_mutex);
        return chan;
@@ -231,6 +236,8 @@ struct ltt_channel *ltt_channel_create(struct ltt_session *session,
 create_error:
        kfree(chan);
 nomem:
+       if (transport)
+               module_put(transport->owner);
 notransport:
 active:
        mutex_unlock(&sessions_mutex);
@@ -244,6 +251,7 @@ static
 void _ltt_channel_destroy(struct ltt_channel *chan)
 {
        chan->ops->channel_destroy(chan->chan);
+       module_put(chan->transport->owner);
        list_del(&chan->list);
        lttng_destroy_context(chan->ctx);
        kfree(chan);

diff --git a/ltt-events.h b/ltt-events.h
index 304bcb69989b406d8c3b02d76f3320ca5321324c..8cbe8efb5c691de42d845c9442c9e5aed91c3e8d 100644 (file)
--- a/ltt-events.h
+++ b/ltt-events.h
@@ -210,6 +210,13 @@ struct ltt_channel_ops {
        int (*is_disabled)(struct channel *chan);
 };
 
+struct ltt_transport {
+       char *name;
+       struct module *owner;
+       struct list_head node;
+       struct ltt_channel_ops ops;
+};
+
 struct ltt_channel {
        unsigned int id;
        struct channel *chan;           /* Channel buffers */
@@ -221,6 +228,7 @@ struct ltt_channel {
        unsigned int free_event_id;     /* Next event ID to allocate */
        struct list_head list;          /* Channel list */
        struct ltt_channel_ops *ops;
+       struct ltt_transport *transport;
        int header_type;                /* 0: unset, 1: compact, 2: large */
        int metadata_dumped:1;
 };
@@ -238,13 +246,6 @@ struct ltt_session {
        int metadata_dumped:1;
 };
 
-struct ltt_transport {
-       char *name;
-       struct module *owner;
-       struct list_head node;
-       struct ltt_channel_ops ops;
-};
-
 struct ltt_session *ltt_session_create(void);
 int ltt_session_enable(struct ltt_session *session);
 int ltt_session_disable(struct ltt_session *session);