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Fixed race on duplicate device registering or device unregistering while requesting master.

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This commit is contained in:
Florian Pose
2006-09-28 12:58:06 +00:00
parent dad884291e
commit 302b826fe1
3 changed files with 29 additions and 4 deletions
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master/module.c
+26 -4
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@@ -290,15 +290,20 @@ ec_device_t *ecdev_register(unsigned int master_index, /**< master index */
if (!(master = ec_find_master(master_index))) return NULL;
if (down_interruptible(&master->device_sem)) {
EC_ERR("Interrupted while waiting for device!\n");
goto out_return;
}
if (master->device) {
EC_ERR("Master %i already has a device!\n", master_index);
goto out_return;
goto out_up;
}
if (!(master->device =
(ec_device_t *) kmalloc(sizeof(ec_device_t), GFP_KERNEL))) {
EC_ERR("Failed to allocate device!\n");
goto out_return;
goto out_up;
}
if (ec_device_init(master->device, master, net_dev, isr, module)) {
@@ -306,11 +311,14 @@ ec_device_t *ecdev_register(unsigned int master_index, /**< master index */
goto out_free;
}
up(&master->device_sem);
return master->device;
out_free:
kfree(master->device);
master->device = NULL;
out_up:
up(&master->device_sem);
out_return:
return NULL;
}
@@ -334,7 +342,10 @@ void ecdev_unregister(unsigned int master_index, /**< master index */
if (!(master = ec_find_master(master_index))) return;
down(&master->device_sem);
if (!master->device || master->device != device) {
up(&master->device_sem);
EC_WARN("Unable to unregister device!\n");
return;
}
@@ -342,6 +353,8 @@ void ecdev_unregister(unsigned int master_index, /**< master index */
ec_device_clear(master->device);
kfree(master->device);
master->device = NULL;
up(&master->device_sem);
}
/*****************************************************************************/
@@ -415,16 +428,25 @@ ec_master_t *ecrt_request_master(unsigned int master_index
goto out_return;
}
if (down_interruptible(&master->device_sem)) {
EC_ERR("Interrupted while waiting for device!\n");
goto out_release;
}
if (!master->device) {
up(&master->device_sem);
EC_ERR("Master %i has no assigned device!\n", master_index);
goto out_release;
}
if (!try_module_get(master->device->module)) { // possible race?
EC_ERR("Failed to reserve device module!\n");
if (!try_module_get(master->device->module)) {
up(&master->device_sem);
EC_ERR("Device module is unloading!\n");
goto out_release;
}
up(&master->device_sem);
if (!master->device->link_state) {
EC_ERR("Link is DOWN.\n");
goto out_module_put;