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CAPI: Rework locking of capidev members
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Rename 'ncci_list_mtx' to 'lock', expressing that it now protects a
larger set of capidev members: the NCCI list, ap.applid (ie. the
registration of the application), and modifications of userflags.

We do not need to protect each and every check for ap.applid because,
once an application is registered, it will stay for the whole lifetime
of the device.

Also, there is no need to apply the capidev mutex during release (if
there could be concurrent users, we would crash them anyway by freeing
the device at the end of capi_release).

Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Jan Kiszka authored and David S. Miller committed Feb 17, 2010
1 parent eca39dd commit 05b4149
Showing 1 changed file with 88 additions and 93 deletions.
181 changes: 88 additions & 93 deletions drivers/isdn/capi/capi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -141,7 +141,7 @@ struct capidev {

struct capincci *nccis;

struct mutex ncci_list_mtx;
struct mutex lock;
};

/* -------- global variables ---------------------------------------- */
Expand Down Expand Up @@ -574,38 +574,31 @@ static void capi_recv_message(struct capi20_appl *ap, struct sk_buff *skb)
u16 datahandle;
#endif /* CONFIG_ISDN_CAPI_MIDDLEWARE */
struct capincci *np;
u32 ncci;
unsigned long flags;

mutex_lock(&cdev->lock);

if (CAPIMSG_CMD(skb->data) == CAPI_CONNECT_B3_CONF) {
u16 info = CAPIMSG_U16(skb->data, 12); // Info field
if ((info & 0xff00) == 0) {
mutex_lock(&cdev->ncci_list_mtx);
if ((info & 0xff00) == 0)
capincci_alloc(cdev, CAPIMSG_NCCI(skb->data));
mutex_unlock(&cdev->ncci_list_mtx);
}
}
if (CAPIMSG_CMD(skb->data) == CAPI_CONNECT_B3_IND) {
mutex_lock(&cdev->ncci_list_mtx);
if (CAPIMSG_CMD(skb->data) == CAPI_CONNECT_B3_IND)
capincci_alloc(cdev, CAPIMSG_NCCI(skb->data));
mutex_unlock(&cdev->ncci_list_mtx);
}

spin_lock_irqsave(&workaround_lock, flags);
if (CAPIMSG_COMMAND(skb->data) != CAPI_DATA_B3) {
skb_queue_tail(&cdev->recvqueue, skb);
wake_up_interruptible(&cdev->recvwait);
spin_unlock_irqrestore(&workaround_lock, flags);
return;
goto unlock_out;
}
ncci = CAPIMSG_CONTROL(skb->data);
for (np = cdev->nccis; np && np->ncci != ncci; np = np->next)
;

np = capincci_find(cdev, CAPIMSG_CONTROL(skb->data));
if (!np) {
printk(KERN_ERR "BUG: capi_signal: ncci not found\n");
skb_queue_tail(&cdev->recvqueue, skb);
wake_up_interruptible(&cdev->recvwait);
spin_unlock_irqrestore(&workaround_lock, flags);
return;
goto unlock_out;
}

#ifndef CONFIG_ISDN_CAPI_MIDDLEWARE
Expand All @@ -618,8 +611,7 @@ static void capi_recv_message(struct capi20_appl *ap, struct sk_buff *skb)
if (!mp) {
skb_queue_tail(&cdev->recvqueue, skb);
wake_up_interruptible(&cdev->recvwait);
spin_unlock_irqrestore(&workaround_lock, flags);
return;
goto unlock_out;
}
if (CAPIMSG_SUBCOMMAND(skb->data) == CAPI_IND) {
datahandle = CAPIMSG_U16(skb->data, CAPIMSG_BASELEN+4+4+2);
Expand Down Expand Up @@ -652,7 +644,9 @@ static void capi_recv_message(struct capi20_appl *ap, struct sk_buff *skb)
}
#endif /* CONFIG_ISDN_CAPI_MIDDLEWARE */

unlock_out:
spin_unlock_irqrestore(&workaround_lock, flags);
mutex_unlock(&cdev->lock);
}

/* -------- file_operations for capidev ----------------------------- */
Expand Down Expand Up @@ -730,9 +724,9 @@ capi_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos
CAPIMSG_SETAPPID(skb->data, cdev->ap.applid);

if (CAPIMSG_CMD(skb->data) == CAPI_DISCONNECT_B3_RESP) {
mutex_lock(&cdev->ncci_list_mtx);
mutex_lock(&cdev->lock);
capincci_free(cdev, CAPIMSG_NCCI(skb->data));
mutex_unlock(&cdev->ncci_list_mtx);
mutex_unlock(&cdev->lock);
}

cdev->errcode = capi20_put_message(&cdev->ap, skb);
Expand Down Expand Up @@ -765,30 +759,35 @@ capi_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
struct capidev *cdev = file->private_data;
struct capi20_appl *ap = &cdev->ap;
capi_ioctl_struct data;
int retval = -EINVAL;
void __user *argp = (void __user *)arg;

switch (cmd) {
case CAPI_REGISTER:
{
if (ap->applid)
return -EEXIST;
mutex_lock(&cdev->lock);

if (copy_from_user(&cdev->ap.rparam, argp,
sizeof(struct capi_register_params)))
return -EFAULT;

cdev->ap.private = cdev;
cdev->ap.recv_message = capi_recv_message;
cdev->errcode = capi20_register(ap);
if (cdev->errcode) {
ap->applid = 0;
return -EIO;
}
if (cdev->ap.applid) {
retval = -EEXIST;
goto register_out;
}
if (copy_from_user(&cdev->ap.rparam, argp,
sizeof(struct capi_register_params))) {
retval = -EFAULT;
goto register_out;
}
cdev->ap.private = cdev;
cdev->ap.recv_message = capi_recv_message;
cdev->errcode = capi20_register(&cdev->ap);
retval = (int)cdev->ap.applid;
if (cdev->errcode) {
cdev->ap.applid = 0;
retval = -EIO;
}
return (int)ap->applid;

register_out:
mutex_unlock(&cdev->lock);
return retval;

case CAPI_GET_VERSION:
{
Expand Down Expand Up @@ -887,68 +886,67 @@ capi_ioctl(struct inode *inode, struct file *file,
return 0;

case CAPI_SET_FLAGS:
case CAPI_CLR_FLAGS:
{
unsigned userflags;
if (copy_from_user(&userflags, argp,
sizeof(userflags)))
return -EFAULT;
if (cmd == CAPI_SET_FLAGS)
cdev->userflags |= userflags;
else
cdev->userflags &= ~userflags;
}
return 0;
case CAPI_CLR_FLAGS: {
unsigned userflags;

if (copy_from_user(&userflags, argp, sizeof(userflags)))
return -EFAULT;

mutex_lock(&cdev->lock);
if (cmd == CAPI_SET_FLAGS)
cdev->userflags |= userflags;
else
cdev->userflags &= ~userflags;
mutex_unlock(&cdev->lock);
return 0;
}
case CAPI_GET_FLAGS:
if (copy_to_user(argp, &cdev->userflags,
sizeof(cdev->userflags)))
return -EFAULT;
return 0;

case CAPI_NCCI_OPENCOUNT:
{
struct capincci *nccip;
unsigned ncci;
int count = 0;
if (copy_from_user(&ncci, argp, sizeof(ncci)))
return -EFAULT;
case CAPI_NCCI_OPENCOUNT: {
struct capincci *nccip;
unsigned ncci;
int count = 0;

mutex_lock(&cdev->ncci_list_mtx);
if ((nccip = capincci_find(cdev, (u32) ncci)) == NULL) {
mutex_unlock(&cdev->ncci_list_mtx);
return 0;
}
count += capincci_minor_opencount(nccip);
mutex_unlock(&cdev->ncci_list_mtx);
return count;
}
return 0;
if (copy_from_user(&ncci, argp, sizeof(ncci)))
return -EFAULT;

mutex_lock(&cdev->lock);
nccip = capincci_find(cdev, (u32)ncci);
if (nccip)
count = capincci_minor_opencount(nccip);
mutex_unlock(&cdev->lock);
return count;
}

#ifdef CONFIG_ISDN_CAPI_MIDDLEWARE
case CAPI_NCCI_GETUNIT:
{
struct capincci *nccip;
struct capiminor *mp;
unsigned ncci;
int unit = 0;
if (copy_from_user(&ncci, argp,
sizeof(ncci)))
return -EFAULT;
mutex_lock(&cdev->ncci_list_mtx);
nccip = capincci_find(cdev, (u32) ncci);
if (!nccip || (mp = nccip->minorp) == NULL) {
mutex_unlock(&cdev->ncci_list_mtx);
return -ESRCH;
}
unit = mp->minor;
mutex_unlock(&cdev->ncci_list_mtx);
return unit;
case CAPI_NCCI_GETUNIT: {
struct capincci *nccip;
struct capiminor *mp;
unsigned ncci;
int unit = -ESRCH;

if (copy_from_user(&ncci, argp, sizeof(ncci)))
return -EFAULT;

mutex_lock(&cdev->lock);
nccip = capincci_find(cdev, (u32)ncci);
if (nccip) {
mp = nccip->minorp;
if (mp)
unit = mp->minor;
}
return 0;
mutex_unlock(&cdev->lock);
return unit;
}
#endif /* CONFIG_ISDN_CAPI_MIDDLEWARE */

default:
return -EINVAL;
}
return -EINVAL;
}

static int capi_open(struct inode *inode, struct file *file)
Expand All @@ -959,7 +957,7 @@ static int capi_open(struct inode *inode, struct file *file)
if (!cdev)
return -ENOMEM;

mutex_init(&cdev->ncci_list_mtx);
mutex_init(&cdev->lock);
skb_queue_head_init(&cdev->recvqueue);
init_waitqueue_head(&cdev->recvwait);
file->private_data = cdev;
Expand All @@ -979,15 +977,10 @@ static int capi_release(struct inode *inode, struct file *file)
list_del(&cdev->list);
mutex_unlock(&capidev_list_lock);

if (cdev->ap.applid) {
if (cdev->ap.applid)
capi20_release(&cdev->ap);
cdev->ap.applid = 0;
}
skb_queue_purge(&cdev->recvqueue);

mutex_lock(&cdev->ncci_list_mtx);
capincci_free(cdev, 0xffffffff);
mutex_unlock(&cdev->ncci_list_mtx);

kfree(cdev);
return 0;
Expand Down Expand Up @@ -1446,11 +1439,13 @@ static int capi20ncci_proc_show(struct seq_file *m, void *v)
mutex_lock(&capidev_list_lock);
list_for_each(l, &capidev_list) {
cdev = list_entry(l, struct capidev, list);
mutex_lock(&cdev->lock);
for (np=cdev->nccis; np; np = np->next) {
seq_printf(m, "%d 0x%x\n",
cdev->ap.applid,
np->ncci);
}
mutex_unlock(&cdev->lock);
}
mutex_unlock(&capidev_list_lock);
return 0;
Expand Down

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