From: viro@parcelfarce.linux.theplanet.co.uk
daisy.c used to access the topology list with no locking whatsoever.
Protected by spinlock, fixed numerous bugs in handling of the single-linked
list (I'm not kidding - just take a look at the old parport_daisy_fini() and
weep; it is supposed to go through a simple list and remove all entries that
satisfy a condition).
---
25-akpm/drivers/parport/daisy.c | 120 +++++++++++++++++++++++-----------------
1 files changed, 69 insertions(+), 51 deletions(-)
diff -puN drivers/parport/daisy.c~PP5-daisy-RC1 drivers/parport/daisy.c
--- 25/drivers/parport/daisy.c~PP5-daisy-RC1 Wed Jan 14 13:50:50 2004
+++ 25-akpm/drivers/parport/daisy.c Wed Jan 14 13:50:50 2004
@@ -40,6 +40,7 @@ static struct daisydev {
int daisy;
int devnum;
} *topology = NULL;
+static spinlock_t topology_lock = SPIN_LOCK_UNLOCKED;
static int numdevs = 0;
@@ -52,22 +53,18 @@ static int assign_addrs (struct parport
/* Add a device to the discovered topology. */
static void add_dev (int devnum, struct parport *port, int daisy)
{
- struct daisydev *newdev;
+ struct daisydev *newdev, **p;
newdev = kmalloc (sizeof (struct daisydev), GFP_KERNEL);
if (newdev) {
newdev->port = port;
newdev->daisy = daisy;
newdev->devnum = devnum;
- newdev->next = topology;
- if (!topology || topology->devnum >= devnum)
- topology = newdev;
- else {
- struct daisydev *prev = topology;
- while (prev->next && prev->next->devnum < devnum)
- prev = prev->next;
- newdev->next = prev->next;
- prev->next = newdev;
- }
+ spin_lock(&topology_lock);
+ for (p = &topology; *p && (*p)->devnum<devnum; p = &(*p)->next)
+ ;
+ newdev->next = *p;
+ *p = newdev;
+ spin_unlock(&topology_lock);
}
}
@@ -157,26 +154,25 @@ int parport_daisy_init (struct parport *
/* Forget about devices on a physical port. */
void parport_daisy_fini (struct parport *port)
{
- struct daisydev *dev, *prev = topology;
- while (prev && prev->port == port) {
- topology = topology->next;
- kfree (prev);
- prev = topology;
- }
+ struct daisydev **p;
- while (prev) {
- dev = prev->next;
- if (dev && dev->port == port) {
- prev->next = dev->next;
- kfree (dev);
+ spin_lock(&topology_lock);
+ p = &topology;
+ while (*p) {
+ struct daisydev *dev = *p;
+ if (dev->port != port) {
+ p = &dev->next;
+ continue;
}
- prev = prev->next;
+ *p = dev->next;
+ kfree(dev);
}
/* Gaps in the numbering could be handled better. How should
someone enumerate through all IEEE1284.3 devices in the
topology?. */
if (!topology) numdevs = 0;
+ spin_unlock(&topology_lock);
return;
}
@@ -205,30 +201,34 @@ struct pardevice *parport_open (int devn
void (*irqf) (int, void *, struct pt_regs *),
int flags, void *handle)
{
- struct parport *port = parport_enumerate ();
+ struct daisydev *p = topology;
+ struct parport *port;
struct pardevice *dev;
- int portnum;
- int muxnum;
- int daisynum;
-
- if (parport_device_coords (devnum, &portnum, &muxnum, &daisynum))
- return NULL;
+ int daisy;
- while (port && ((port->portnum != portnum) ||
- (port->muxport != muxnum)))
- port = port->next;
+ spin_lock(&topology_lock);
+ while (p && p->devnum != devnum)
+ p = p->next;
- if (!port)
- /* No corresponding parport. */
+ if (!p) {
+ spin_unlock(&topology_lock);
return NULL;
+ }
+
+ daisy = p->daisy;
+ port = parport_get_port(p->port);
+ spin_unlock(&topology_lock);
dev = parport_register_device (port, name, pf, kf,
irqf, flags, handle);
- if (dev)
- dev->daisy = daisynum;
+ parport_put_port(port);
+ if (!dev)
+ return NULL;
+
+ dev->daisy = daisy;
/* Check that there really is a device to select. */
- if (daisynum >= 0) {
+ if (daisy >= 0) {
int selected;
parport_claim_or_block (dev);
selected = port->daisy;
@@ -271,16 +271,19 @@ void parport_close (struct pardevice *de
int parport_device_num (int parport, int mux, int daisy)
{
- struct daisydev *dev = topology;
+ int res = -ENXIO;
+ struct daisydev *dev;
+ spin_lock(&topology_lock);
+ dev = topology;
while (dev && dev->port->portnum != parport &&
dev->port->muxport != mux && dev->daisy != daisy)
dev = dev->next;
+ if (dev)
+ res = dev->devnum;
+ spin_unlock(&topology_lock);
- if (!dev)
- return -ENXIO;
-
- return dev->devnum;
+ return res;
}
/**
@@ -310,17 +313,23 @@ int parport_device_num (int parport, int
int parport_device_coords (int devnum, int *parport, int *mux, int *daisy)
{
- struct daisydev *dev = topology;
+ struct daisydev *dev;
+ spin_lock(&topology_lock);
+
+ dev = topology;
while (dev && dev->devnum != devnum)
dev = dev->next;
- if (!dev)
+ if (!dev) {
+ spin_unlock(&topology_lock);
return -ENXIO;
+ }
if (parport) *parport = dev->port->portnum;
if (mux) *mux = dev->port->muxport;
if (daisy) *daisy = dev->daisy;
+ spin_unlock(&topology_lock);
return 0;
}
@@ -557,9 +566,13 @@ static int assign_addrs (struct parport
int parport_find_device (const char *mfg, const char *mdl, int from)
{
- struct daisydev *d = topology; /* sorted by devnum */
+ struct daisydev *d;
+ int res = -1;
/* Find where to start. */
+
+ spin_lock(&topology_lock);
+ d = topology; /* sorted by devnum */
while (d && d->devnum <= from)
d = d->next;
@@ -575,9 +588,10 @@ int parport_find_device (const char *mfg
}
if (d)
- return d->devnum;
+ res = d->devnum;
- return -1;
+ spin_unlock(&topology_lock);
+ return res;
}
/**
@@ -601,8 +615,11 @@ int parport_find_device (const char *mfg
int parport_find_class (parport_device_class cls, int from)
{
- struct daisydev *d = topology; /* sorted by devnum */
+ struct daisydev *d;
+ int res = -1;
+ spin_lock(&topology_lock);
+ d = topology; /* sorted by devnum */
/* Find where to start. */
while (d && d->devnum <= from)
d = d->next;
@@ -612,7 +629,8 @@ int parport_find_class (parport_device_c
d = d->next;
if (d)
- return d->devnum;
+ res = d->devnum;
- return -1;
+ spin_unlock(&topology_lock);
+ return res;
}
_