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firewire: nosy: fix device shutdown with active client 

Fix race between nosy_open() and remove_card() by replacing the
unprotected array of card pointers by a mutex-protected list of cards.

Make card instances reference-counted and let each client hold a
reference.

Notify clients about card removal via POLLHUP in poll()'s events
bitmap; also let read() fail with errno=ENODEV if the card was removed
and everything in the buffer was read.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Stefan Richter 2010-07-22 11:56:38 +02:00
parent b6d9c125e6
commit 424d66ceda
1 changed files with 81 additions and 28 deletions
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109
drivers/firewire/nosy.c
View File

@ -23,8 +23,10 @@
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/poll.h>
#include <linux/sched.h> /* required for linux/wait.h */
@ -104,8 +106,30 @@ struct pcilynx {
struct list_head client_list;
struct miscdevice misc;
struct list_head link;
struct kref kref;
};
static inline struct pcilynx *
lynx_get(struct pcilynx *lynx)
{
kref_get(&lynx->kref);
return lynx;
}
static void
lynx_release(struct kref *kref)
{
kfree(container_of(kref, struct pcilynx, kref));
}
static inline void
lynx_put(struct pcilynx *lynx)
{
kref_put(&lynx->kref, lynx_release);
}
struct client {
struct pcilynx *lynx;
u32 tcode_mask;
@ -113,8 +137,8 @@ struct client {
struct list_head link;
};
#define MAX_MINORS 64
static struct pcilynx *minors[MAX_MINORS];
static DEFINE_MUTEX(card_mutex);
static LIST_HEAD(card_list);
static int
packet_buffer_init(struct packet_buffer *buffer, size_t capacity)
@ -139,15 +163,20 @@ packet_buffer_destroy(struct packet_buffer *buffer)
}
static int
packet_buffer_get(struct packet_buffer *buffer, void *data, size_t user_length)
packet_buffer_get(struct client *client, void *data, size_t user_length)
{
struct packet_buffer *buffer = &client->buffer;
size_t length;
char *end;
if (wait_event_interruptible(buffer->wait,
atomic_read(&buffer->size) > 0))
atomic_read(&buffer->size) > 0) ||
list_empty(&client->lynx->link))
return -ERESTARTSYS;
if (atomic_read(&buffer->size) == 0)
return -ENODEV;
/* FIXME: Check length <= user_length. */
end = buffer->data + buffer->capacity;
@ -265,39 +294,52 @@ nosy_open(struct inode *inode, struct file *file)
{
int minor = iminor(inode);
struct client *client;
struct pcilynx *tmp, *lynx = NULL;
if (minor > MAX_MINORS || minors[minor] == NULL)
mutex_lock(&card_mutex);
list_for_each_entry(tmp, &card_list, link)
if (tmp->misc.minor == minor) {
lynx = lynx_get(tmp);
break;
}
mutex_unlock(&card_mutex);
if (lynx == NULL)
return -ENODEV;
client = kmalloc(sizeof *client, GFP_KERNEL);
if (client == NULL)
return -ENOMEM;
goto fail;
client->tcode_mask = ~0;
client->lynx = minors[minor];
client->lynx = lynx;
INIT_LIST_HEAD(&client->link);
if (packet_buffer_init(&client->buffer, 128 * 1024) < 0) {
kfree(client);
return -ENOMEM;
}
if (packet_buffer_init(&client->buffer, 128 * 1024) < 0)
goto fail;
file->private_data = client;
return 0;
fail:
kfree(client);
lynx_put(lynx);
return -ENOMEM;
}
static int
nosy_release(struct inode *inode, struct file *file)
{
struct client *client = file->private_data;
struct pcilynx *lynx = client->lynx;
spin_lock_irq(&client->lynx->client_list_lock);
spin_lock_irq(&lynx->client_list_lock);
list_del_init(&client->link);
spin_unlock_irq(&client->lynx->client_list_lock);
spin_unlock_irq(&lynx->client_list_lock);
packet_buffer_destroy(&client->buffer);
kfree(client);
lynx_put(lynx);
return 0;
}
@ -306,13 +348,17 @@ static unsigned int
nosy_poll(struct file *file, poll_table *pt)
{
struct client *client = file->private_data;
unsigned int ret = 0;
poll_wait(file, &client->buffer.wait, pt);
if (atomic_read(&client->buffer.size) > 0)
return POLLIN | POLLRDNORM;
else
return 0;
ret = POLLIN | POLLRDNORM;
if (list_empty(&client->lynx->link))
ret |= POLLHUP;
return ret;
}
static ssize_t
@ -320,7 +366,7 @@ nosy_read(struct file *file, char *buffer, size_t count, loff_t *offset)
{
struct client *client = file->private_data;
return packet_buffer_get(&client->buffer, buffer, count);
return packet_buffer_get(client, buffer, count);
}
static long
@ -479,16 +525,22 @@ irq_handler(int irq, void *device)
static void
remove_card(struct pci_dev *dev)
{
struct pcilynx *lynx;
struct pcilynx *lynx = pci_get_drvdata(dev);
struct client *client;
lynx = pci_get_drvdata(dev);
if (!lynx)
return;
pci_set_drvdata(dev, NULL);
mutex_lock(&card_mutex);
list_del_init(&lynx->link);
misc_deregister(&lynx->misc);
mutex_unlock(&card_mutex);
reg_write(lynx, PCI_INT_ENABLE, 0);
free_irq(lynx->pci_device->irq, lynx);
spin_lock_irq(&lynx->client_list_lock);
list_for_each_entry(client, &lynx->client_list, link)
wake_up_interruptible(&client->buffer.wait);
spin_unlock_irq(&lynx->client_list_lock);
pci_free_consistent(lynx->pci_device, sizeof(struct pcl),
lynx->rcv_start_pcl, lynx->rcv_start_pcl_bus);
pci_free_consistent(lynx->pci_device, sizeof(struct pcl),
@ -498,11 +550,7 @@ remove_card(struct pci_dev *dev)
iounmap(lynx->registers);
pci_disable_device(dev);
minors[lynx->misc.minor] = NULL;
misc_deregister(&lynx->misc);
kfree(lynx);
lynx_put(lynx);
}
#define RCV_BUFFER_SIZE (16 * 1024)
@ -536,6 +584,7 @@ add_card(struct pci_dev *dev, const struct pci_device_id *unused)
spin_lock_init(&lynx->client_list_lock);
INIT_LIST_HEAD(&lynx->client_list);
kref_init(&lynx->kref);
lynx->registers = ioremap_nocache(pci_resource_start(dev, 0),
PCILYNX_MAX_REGISTER);
@ -619,12 +668,16 @@ add_card(struct pci_dev *dev, const struct pci_device_id *unused)
lynx->misc.minor = MISC_DYNAMIC_MINOR;
lynx->misc.name = "nosy";
lynx->misc.fops = &nosy_ops;
mutex_lock(&card_mutex);
ret = misc_register(&lynx->misc);
if (ret) {
error("Failed to register misc char device\n");
mutex_unlock(&card_mutex);
goto fail_free_irq;
}
minors[lynx->misc.minor] = lynx;
list_add_tail(&lynx->link, &card_list);
mutex_unlock(&card_mutex);
notify("Initialized PCILynx IEEE1394 card, irq=%d\n", dev->irq);