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

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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1
master/master.c
View File

@ -109,6 +109,7 @@ int ec_master_init(ec_master_t *master, /**< EtherCAT master */
master->index = index;
master->device = NULL;
init_MUTEX(&master->device_sem);
atomic_set(&master->available, 1);
INIT_LIST_HEAD(&master->slaves);
INIT_LIST_HEAD(&master->datagram_queue);

2
master/master.h
View File

@ -45,6 +45,7 @@
#include <linux/sysfs.h>
#include <linux/timer.h>
#include <asm/atomic.h>
#include <asm/semaphore.h>
#include "device.h"
#include "domain.h"
@ -99,6 +100,7 @@ struct ec_master
struct kobject kobj; /**< kobject */
ec_device_t *device; /**< EtherCAT device */
struct semaphore device_sem; /**< device semaphore */
ec_xmldev_t xmldev; /**< XML character device */

30
master/module.c
View File

@ -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;