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firewire: cdev: use an idr rather than a linked list for resources
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The current code uses a linked list and a counter for storing
resources and the corresponding handle numbers.  By changing to an idr
we can be safe from counter wrap-around giving two resources the same
handle.

Furthermore, the deallocation ioctls now check whether the resource to
be freed is of the intended type.

Signed-off-by: Jay Fenlason <fenlason@redhat.com>

Some rework by Stefan R:
  - The idr API documentation says we get an ID within 0...0x7fffffff.
    Hence we can rest assured that idr handles fit into cdev handles.
  - Fix some races.  Add a client->in_shutdown flag for this purpose.
  - Add allocation retry to add_client_resource().
  - It is possible to use idr_for_each() in fw_device_op_release().
  - Fix ioctl_send_response() regression.
  - Small style changes.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
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Jay Fenlason authored and Stefan Richter committed Mar 24, 2009
1 parent 97811e3 commit 45ee319
Showing 1 changed file with 114 additions and 51 deletions.
165 changes: 114 additions & 51 deletions drivers/firewire/fw-cdev.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -41,10 +41,12 @@
#include "fw-device.h"

struct client;
struct client_resource;
typedef void (*client_resource_release_fn_t)(struct client *,
struct client_resource *);
struct client_resource {
struct list_head link;
void (*release)(struct client *client, struct client_resource *r);
u32 handle;
client_resource_release_fn_t release;
int handle;
};

/*
Expand Down Expand Up @@ -78,9 +80,10 @@ struct iso_interrupt {
struct client {
u32 version;
struct fw_device *device;

spinlock_t lock;
u32 resource_handle;
struct list_head resource_list;
bool in_shutdown;
struct idr resource_idr;
struct list_head event_list;
wait_queue_head_t wait;
u64 bus_reset_closure;
Expand Down Expand Up @@ -126,9 +129,9 @@ static int fw_device_op_open(struct inode *inode, struct file *file)
}

client->device = device;
INIT_LIST_HEAD(&client->event_list);
INIT_LIST_HEAD(&client->resource_list);
spin_lock_init(&client->lock);
idr_init(&client->resource_idr);
INIT_LIST_HEAD(&client->event_list);
init_waitqueue_head(&client->wait);

file->private_data = client;
Expand All @@ -151,7 +154,10 @@ static void queue_event(struct client *client, struct event *event,
event->v[1].size = size1;

spin_lock_irqsave(&client->lock, flags);
list_add_tail(&event->link, &client->event_list);
if (client->in_shutdown)
kfree(event);
else
list_add_tail(&event->link, &client->event_list);
spin_unlock_irqrestore(&client->lock, flags);

wake_up_interruptible(&client->wait);
Expand Down Expand Up @@ -310,34 +316,49 @@ static int ioctl_get_info(struct client *client, void *buffer)
return 0;
}

static void
add_client_resource(struct client *client, struct client_resource *resource)
static int
add_client_resource(struct client *client, struct client_resource *resource,
gfp_t gfp_mask)
{
unsigned long flags;
int ret;

retry:
if (idr_pre_get(&client->resource_idr, gfp_mask) == 0)
return -ENOMEM;

spin_lock_irqsave(&client->lock, flags);
list_add_tail(&resource->link, &client->resource_list);
resource->handle = client->resource_handle++;
if (client->in_shutdown)
ret = -ECANCELED;
else
ret = idr_get_new(&client->resource_idr, resource,
&resource->handle);
spin_unlock_irqrestore(&client->lock, flags);

if (ret == -EAGAIN)
goto retry;

return ret < 0 ? ret : 0;
}

static int
release_client_resource(struct client *client, u32 handle,
client_resource_release_fn_t release,
struct client_resource **resource)
{
struct client_resource *r;
unsigned long flags;

spin_lock_irqsave(&client->lock, flags);
list_for_each_entry(r, &client->resource_list, link) {
if (r->handle == handle) {
list_del(&r->link);
break;
}
}
if (client->in_shutdown)
r = NULL;
else
r = idr_find(&client->resource_idr, handle);
if (r && r->release == release)
idr_remove(&client->resource_idr, handle);
spin_unlock_irqrestore(&client->lock, flags);

if (&r->link == &client->resource_list)
if (!(r && r->release == release))
return -EINVAL;

if (resource)
Expand Down Expand Up @@ -372,7 +393,12 @@ complete_transaction(struct fw_card *card, int rcode,
memcpy(r->data, payload, r->length);

spin_lock_irqsave(&client->lock, flags);
list_del(&response->resource.link);
/*
* If called while in shutdown, the idr tree must be left untouched.
* The idr handle will be removed later.
*/
if (!client->in_shutdown)
idr_remove(&client->resource_idr, response->resource.handle);
spin_unlock_irqrestore(&client->lock, flags);

r->type = FW_CDEV_EVENT_RESPONSE;
Expand Down Expand Up @@ -416,7 +442,7 @@ static int ioctl_send_request(struct client *client, void *buffer)
copy_from_user(response->response.data,
u64_to_uptr(request->data), request->length)) {
ret = -EFAULT;
goto err;
goto failed;
}

switch (request->tcode) {
Expand All @@ -434,11 +460,13 @@ static int ioctl_send_request(struct client *client, void *buffer)
break;
default:
ret = -EINVAL;
goto err;
goto failed;
}

response->resource.release = release_transaction;
add_client_resource(client, &response->resource);
ret = add_client_resource(client, &response->resource, GFP_KERNEL);
if (ret < 0)
goto failed;

fw_send_request(device->card, &response->transaction,
request->tcode & 0x1f,
Expand All @@ -453,7 +481,7 @@ static int ioctl_send_request(struct client *client, void *buffer)
return sizeof(request) + request->length;
else
return sizeof(request);
err:
failed:
kfree(response);

return ret;
Expand Down Expand Up @@ -500,22 +528,21 @@ handle_request(struct fw_card *card, struct fw_request *r,
struct request *request;
struct request_event *e;
struct client *client = handler->client;
int ret;

request = kmalloc(sizeof(*request), GFP_ATOMIC);
e = kmalloc(sizeof(*e), GFP_ATOMIC);
if (request == NULL || e == NULL) {
kfree(request);
kfree(e);
fw_send_response(card, r, RCODE_CONFLICT_ERROR);
return;
}
if (request == NULL || e == NULL)
goto failed;

request->request = r;
request->data = payload;
request->length = length;

request->resource.release = release_request;
add_client_resource(client, &request->resource);
ret = add_client_resource(client, &request->resource, GFP_ATOMIC);
if (ret < 0)
goto failed;

e->request.type = FW_CDEV_EVENT_REQUEST;
e->request.tcode = tcode;
Expand All @@ -526,6 +553,12 @@ handle_request(struct fw_card *card, struct fw_request *r,

queue_event(client, &e->event,
&e->request, sizeof(e->request), payload, length);
return;

failed:
kfree(request);
kfree(e);
fw_send_response(card, r, RCODE_CONFLICT_ERROR);
}

static void
Expand All @@ -544,6 +577,7 @@ static int ioctl_allocate(struct client *client, void *buffer)
struct fw_cdev_allocate *request = buffer;
struct address_handler *handler;
struct fw_address_region region;
int ret;

handler = kmalloc(sizeof(*handler), GFP_KERNEL);
if (handler == NULL)
Expand All @@ -563,7 +597,11 @@ static int ioctl_allocate(struct client *client, void *buffer)
}

handler->resource.release = release_address_handler;
add_client_resource(client, &handler->resource);
ret = add_client_resource(client, &handler->resource, GFP_KERNEL);
if (ret < 0) {
release_address_handler(client, &handler->resource);
return ret;
}
request->handle = handler->resource.handle;

return 0;
Expand All @@ -573,7 +611,8 @@ static int ioctl_deallocate(struct client *client, void *buffer)
{
struct fw_cdev_deallocate *request = buffer;

return release_client_resource(client, request->handle, NULL);
return release_client_resource(client, request->handle,
release_address_handler, NULL);
}

static int ioctl_send_response(struct client *client, void *buffer)
Expand All @@ -582,8 +621,10 @@ static int ioctl_send_response(struct client *client, void *buffer)
struct client_resource *resource;
struct request *r;

if (release_client_resource(client, request->handle, &resource) < 0)
if (release_client_resource(client, request->handle,
release_request, &resource) < 0)
return -EINVAL;

r = container_of(resource, struct request, resource);
if (request->length < r->length)
r->length = request->length;
Expand Down Expand Up @@ -626,7 +667,7 @@ static int ioctl_add_descriptor(struct client *client, void *buffer)
{
struct fw_cdev_add_descriptor *request = buffer;
struct descriptor *descriptor;
int retval;
int ret;

if (request->length > 256)
return -EINVAL;
Expand All @@ -638,33 +679,40 @@ static int ioctl_add_descriptor(struct client *client, void *buffer)

if (copy_from_user(descriptor->data,
u64_to_uptr(request->data), request->length * 4)) {
kfree(descriptor);
return -EFAULT;
ret = -EFAULT;
goto failed;
}

descriptor->d.length = request->length;
descriptor->d.immediate = request->immediate;
descriptor->d.key = request->key;
descriptor->d.data = descriptor->data;

retval = fw_core_add_descriptor(&descriptor->d);
if (retval < 0) {
kfree(descriptor);
return retval;
}
ret = fw_core_add_descriptor(&descriptor->d);
if (ret < 0)
goto failed;

descriptor->resource.release = release_descriptor;
add_client_resource(client, &descriptor->resource);
ret = add_client_resource(client, &descriptor->resource, GFP_KERNEL);
if (ret < 0) {
fw_core_remove_descriptor(&descriptor->d);
goto failed;
}
request->handle = descriptor->resource.handle;

return 0;
failed:
kfree(descriptor);

return ret;
}

static int ioctl_remove_descriptor(struct client *client, void *buffer)
{
struct fw_cdev_remove_descriptor *request = buffer;

return release_client_resource(client, request->handle, NULL);
return release_client_resource(client, request->handle,
release_descriptor, NULL);
}

static void
Expand Down Expand Up @@ -1003,11 +1051,21 @@ static int fw_device_op_mmap(struct file *file, struct vm_area_struct *vma)
return retval;
}

static int shutdown_resource(int id, void *p, void *data)
{
struct client_resource *r = p;
struct client *client = data;

r->release(client, r);

return 0;
}

static int fw_device_op_release(struct inode *inode, struct file *file)
{
struct client *client = file->private_data;
struct event *e, *next_e;
struct client_resource *r, *next_r;
unsigned long flags;

mutex_lock(&client->device->client_list_mutex);
list_del(&client->link);
Expand All @@ -1019,17 +1077,22 @@ static int fw_device_op_release(struct inode *inode, struct file *file)
if (client->iso_context)
fw_iso_context_destroy(client->iso_context);

list_for_each_entry_safe(r, next_r, &client->resource_list, link)
r->release(client, r);
/* Freeze client->resource_idr and client->event_list */
spin_lock_irqsave(&client->lock, flags);
client->in_shutdown = true;
spin_unlock_irqrestore(&client->lock, flags);

/*
* FIXME: We should wait for the async tasklets to stop
* running before freeing the memory.
*/
idr_for_each(&client->resource_idr, shutdown_resource, client);
idr_remove_all(&client->resource_idr);
idr_destroy(&client->resource_idr);

list_for_each_entry_safe(e, next_e, &client->event_list, link)
kfree(e);

/*
* FIXME: client should be reference-counted. It's extremely unlikely
* but there may still be transactions being completed at this point.
*/
fw_device_put(client->device);
kfree(client);

Expand Down

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