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udevd: serialize events for with the same major/minor

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On Wed, Oct 7, 2009 at 21:46, Alan Jenkins <sourcejedi.lkml@googlemail.com> wrote:
> Udev would have avoided the race prior to
>
> 82c785e "udevd: remove check for dev_t, DEVPATH_OLD takes care of that"
>
> (the "check" removed here used to serialize events based on the device
> major:minor number).

On Wed, Oct 7, 2009 at 22:31, Michael Guntsche <mike@it-loops.com> wrote:
> add      /module/8250_pnp (module)
> remove /devices/platform/serial8250/tty/ttyS0 (tty)
> add      /devices/pnp0/00:05/tty/ttyS0 (tty)
This commit is contained in:
Kay Sievers 2009-10-08 00:06:23 +02:00
parent a05cd7ea3e
commit 19711e1933
1 changed files with 19 additions and 12 deletions
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31
udev/udevd.c
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@ -118,6 +118,8 @@ struct event {
const char *devpath;
size_t devpath_len;
const char *devpath_old;
dev_t devnum;
bool is_block;
};
static struct event *node_to_event(struct udev_list_node *node)
@ -410,6 +412,8 @@ static void event_queue_insert(struct udev_device *dev)
event->devpath = udev_device_get_devpath(dev);
event->devpath_len = strlen(event->devpath);
event->devpath_old = udev_device_get_devpath_old(dev);
event->devnum = udev_device_get_devnum(dev);
event->is_block = (strcmp("block", udev_device_get_subsystem(dev)) == 0);
udev_queue_export_device_queued(udev_queue_export, dev);
info(event->udev, "seq %llu queued, '%s' '%s'\n", udev_device_get_seqnum(dev),
@ -473,7 +477,7 @@ static int mem_size_mb(void)
}
/* lookup event for identical, parent, child device */
static int devpath_busy(struct event *event)
static bool is_devpath_busy(struct event *event)
{
struct udev_list_node *loop;
size_t common;
@ -488,18 +492,21 @@ static int devpath_busy(struct event *event)
/* event we checked earlier still exists, no need to check again */
if (loop_event->seqnum == event->delaying_seqnum)
return 2;
return true;
/* found ourself, no later event can block us */
if (loop_event->seqnum >= event->seqnum)
break;
/* check major/minor */
if (major(event->devnum) != 0 && event->devnum == loop_event->devnum && event->is_block == loop_event->is_block)
return true;
/* check our old name */
if (event->devpath_old != NULL)
if (strcmp(loop_event->devpath, event->devpath_old) == 0) {
event->delaying_seqnum = loop_event->seqnum;
return 3;
}
if (event->devpath_old != NULL && strcmp(loop_event->devpath, event->devpath_old) == 0) {
event->delaying_seqnum = loop_event->seqnum;
return true;
}
/* compare devpath */
common = MIN(loop_event->devpath_len, event->devpath_len);
@ -511,26 +518,26 @@ static int devpath_busy(struct event *event)
/* identical device event found */
if (loop_event->devpath_len == event->devpath_len) {
event->delaying_seqnum = loop_event->seqnum;
return 4;
return true;
}
/* parent device event found */
if (event->devpath[common] == '/') {
event->delaying_seqnum = loop_event->seqnum;
return 5;
return true;
}
/* child device event found */
if (loop_event->devpath[common] == '/') {
event->delaying_seqnum = loop_event->seqnum;
return 6;
return true;
}
/* no matching device */
continue;
}
return 0;
return false;
}
static void events_start(struct udev *udev)
@ -544,7 +551,7 @@ static void events_start(struct udev *udev)
continue;
/* do not start event if parent or child event is still running */
if (devpath_busy(event) != 0) {
if (is_devpath_busy(event)) {
dbg(udev, "delay seq %llu (%s)\n", event->seqnum, event->devpath);
continue;
}