On 01/08/11 11:20, Manohar Vanga wrote: > This patch adds functions that allow for reference counting > bridge modules. The patch introduces the functions > 'vme_bridge_get()' and 'vme_bridge_put()'. > > This patch is based on the changes introduced by Emilio G. Cota > in the patch: > > https://lkml.org/lkml/2010/10/25/492 > > Signed-off-by: Manohar Vanga <manohar.vanga@xxxxxxx> > --- > drivers/staging/vme/bridges/vme_ca91cx42.c | 2 + > drivers/staging/vme/bridges/vme_tsi148.c | 2 + > drivers/staging/vme/devices/vme_user.c | 20 +++++++++++ > drivers/staging/vme/vme.c | 48 ++++++++++++++++++++++++++++ > drivers/staging/vme/vme.h | 2 + > drivers/staging/vme/vme_bridge.h | 1 + > 6 files changed, 75 insertions(+), 0 deletions(-) > > diff --git a/drivers/staging/vme/bridges/vme_ca91cx42.c b/drivers/staging/vme/bridges/vme_ca91cx42.c > index 15a0b19..2f9c22b 100644 > --- a/drivers/staging/vme/bridges/vme_ca91cx42.c > +++ b/drivers/staging/vme/bridges/vme_ca91cx42.c > @@ -1680,6 +1680,8 @@ static int ca91cx42_probe(struct pci_dev *pdev, const struct pci_device_id *id) > ca91cx42_bridge->parent = &pdev->dev; > strcpy(ca91cx42_bridge->name, driver_name); > > + ca91cx42_bridge->owner = THIS_MODULE; > + > /* Setup IRQ */ > retval = ca91cx42_irq_init(ca91cx42_bridge); > if (retval != 0) { > diff --git a/drivers/staging/vme/bridges/vme_tsi148.c b/drivers/staging/vme/bridges/vme_tsi148.c > index 5c147d6..9db89dc 100644 > --- a/drivers/staging/vme/bridges/vme_tsi148.c > +++ b/drivers/staging/vme/bridges/vme_tsi148.c > @@ -2320,6 +2320,8 @@ static int tsi148_probe(struct pci_dev *pdev, const struct pci_device_id *id) > tsi148_bridge->parent = &pdev->dev; > strcpy(tsi148_bridge->name, driver_name); > > + tsi148_bridge->owner = THIS_MODULE; > + > /* Setup IRQ */ > retval = tsi148_irq_init(tsi148_bridge); > if (retval != 0) { > diff --git a/drivers/staging/vme/devices/vme_user.c b/drivers/staging/vme/devices/vme_user.c > index 3cbeb2a..7ed4a5c 100644 > --- a/drivers/staging/vme/devices/vme_user.c > +++ b/drivers/staging/vme/devices/vme_user.c > @@ -118,6 +118,8 @@ static struct cdev *vme_user_cdev; /* Character device */ > static struct class *vme_user_sysfs_class; /* Sysfs class */ > static struct device *vme_user_bridge; /* Pointer to bridge device */ > > +static struct vme_bridge *vme_user_bus; /* Pointer to bridge */ > + > > static const int type[VME_DEVS] = { MASTER_MINOR, MASTER_MINOR, > MASTER_MINOR, MASTER_MINOR, > @@ -824,10 +826,25 @@ static int __devinit vme_user_probe(struct device *dev, int cur_bus, > } > } > > + /* > + * Increment reference count of bridge module. We don't want things > + * to fall over in case the bridge module is removed while the vme_user > + * driver is still loaded. > + */ > + vme_user_bus = vme_bridge_get(cur_bus); > + if (!vme_user_bus) { > + printk(KERN_ERR "%s: vme_bridge_get failed\n", driver_name); > + err = -EINVAL; > + goto err_bridge_get; > + } > + Can we not do this inside vme_master_request, vme_slave_request, etc? I.e. Add reference count when resources are given out. > return 0; > > /* Ensure counter set correcty to destroy all sysfs devices */ > i = VME_DEVS; > +err_bridge_get: > + for (i = 0; i < VME_DEVS; i++) > + device_destroy(vme_user_sysfs_class, MKDEV(VME_MAJOR, i)); > err_sysfs: > while (i > 0) { > i--; > @@ -892,6 +909,9 @@ static int __devexit vme_user_remove(struct device *dev, int cur_bus, > /* Unregiser the major and minor device numbers */ > unregister_chrdev_region(MKDEV(VME_MAJOR, 0), VME_DEVS); > > + /* decrement bridge module reference */ > + vme_bridge_put(vme_user_bus); > + This would then be done in the vme_*_free routines. Martyn > return 0; > } > > diff --git a/drivers/staging/vme/vme.c b/drivers/staging/vme/vme.c > index 11e28ca..759ec2b 100644 > --- a/drivers/staging/vme/vme.c > +++ b/drivers/staging/vme/vme.c > @@ -52,6 +52,54 @@ static struct vme_bridge *dev_to_bridge(struct device *dev) > } > > /* > + * Increments the reference count of a VME bridge. > + * > + * If found, a pointer to the bridge is returned and the reference count > + * of the module that owns it is incremented. > + * > + * On success, it can be assumed that the bridge won't be removed until > + * the corresponding call to vme_put_bridge(). > + * > + * Normally drivers should call vme_get_bridge() on a successfull .probe, > + * and vme_put_bridge() when releasing the device, e.g. in .remove. > + */ > +struct vme_bridge *vme_bridge_get(unsigned int bus_id) > +{ > + struct vme_bridge *bridge; > + struct vme_bridge *retp = NULL; > + > + mutex_lock(&vme_buses_lock); > + list_for_each_entry(bridge, &vme_bus_list, bus_list) { > + if (bridge->num == bus_id) { > + if (!bridge->owner) > + dev_warn(bridge->parent, > + "bridge->owner not set\n"); > + else if (try_module_get(bridge->owner)) > + retp = bridge; > + break; > + } > + } > + mutex_unlock(&vme_buses_lock); > + return retp; > +} > +EXPORT_SYMBOL(vme_bridge_get); > + > +/* > + * Decrements the reference count of a bridge > + * > + * This function decrements the reference count of the module that controls > + * the bridge. It must come after a call to vme_get_bridge(). > + */ > +void vme_bridge_put(struct vme_bridge *bridge) > +{ > + if (!bridge->owner) > + dev_warn(bridge->parent, "bridge->owner not set\n"); > + else > + module_put(bridge->owner); > +} > +EXPORT_SYMBOL(vme_bridge_put); > + > +/* > * Find the bridge that the resource is associated with. > */ > static struct vme_bridge *find_bridge(struct vme_resource *resource) > diff --git a/drivers/staging/vme/vme.h b/drivers/staging/vme/vme.h > index 3ccb497..8fb35e2 100644 > --- a/drivers/staging/vme/vme.h > +++ b/drivers/staging/vme/vme.h > @@ -167,6 +167,8 @@ int vme_slot_get(struct device *); > int vme_register_driver(struct vme_driver *); > void vme_unregister_driver(struct vme_driver *); > > +struct vme_bridge *vme_bridge_get(unsigned int bus_id); > +void vme_bridge_put(struct vme_bridge *bridge); > > #endif /* _VME_H_ */ > > diff --git a/drivers/staging/vme/vme_bridge.h b/drivers/staging/vme/vme_bridge.h > index 8959670..ef751a4 100644 > --- a/drivers/staging/vme/vme_bridge.h > +++ b/drivers/staging/vme/vme_bridge.h > @@ -113,6 +113,7 @@ struct vme_bridge { > struct device *parent; /* Parent device (eg. pdev->dev for PCI) */ > void *driver_priv; /* Private pointer for the bridge driver */ > struct list_head bus_list; /* list of VME buses */ > + struct module *owner; /* module that owns the bridge */ > > struct device dev[VME_SLOTS_MAX]; /* Device registered with > * device model on VME bus -- Martyn Welch (Principal Software Engineer) | Registered in England and GE Intelligent Platforms | Wales (3828642) at 100 T +44(0)127322748 | Barbirolli Square, Manchester, E martyn.welch@xxxxxx | M2 3AB VAT:GB 927559189 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
