[PATCH] fix for move_later in udev_enumerate_get_list_entry

[PATCH] fix for move_later in udev_enumerate_get_list_entry

[Thomas de Grenier de Latour]

[-- Attachment #1: Type: text/plain, Size: 1272 bytes --]

Hi,

The attached patch fixes a bug in the udev_enumerate_get_list_entry()
function of "libudev-enumerate.c".  The move_later_prefix variable was
reset to zero on each loop iteration, and thus the move_later entry (if
any) was not added right after changing to another syspath prefix, but
rather after exiting the enumeration loop.

So this patch makes the sound card control node be added asap (after
other nodes from the same sound card) rather than last (after all other
nodes), which is probably a good thing, and obviously seems to be the
original intent of this code.

On my system, under some circumstances, it has the additional benefice
to avoid an "udevadm trigger" segfault.  What was happening was that, at
some point in the loop iteration (a few tens of iterations after it was
set), the move_later->syspath was becoming NULL, and thus the final
udev_list_entry_add() was failing.  I absolutly don't know why it was
becoming NULL though, I've just seen it happening each time I have both
my mouse and keyboard plugged on the monitor USB hub (go figure...).
If this phenomena is of any interest, I can provide some printf-powered 
traces showing it.

I'm not subscribed to the list, so please keep my address in replies.

Thanks,
Thomas de Grenier de Latour.


[-- Attachment #2: fix-enumerate-move-later.patch --]
[-- Type: text/x-patch, Size: 898 bytes --]

diff --git a/libudev/libudev-enumerate.c b/libudev/libudev-enumerate.c
index 53cd53b..605c246 100644
--- a/libudev/libudev-enumerate.c
+++ b/libudev/libudev-enumerate.c
@@ -251,6 +251,7 @@ struct udev_list_entry *udev_enumerate_get_list_entry(struct udev_enumerate *ude
 		unsigned int i;
 		unsigned int max;
 		struct syspath *prev = NULL, *move_later = NULL;
+		size_t move_later_prefix;
 
 		udev_list_cleanup_entries(udev_enumerate->udev, &udev_enumerate->devices_list);
 		qsort(udev_enumerate->devices, udev_enumerate->devices_cur, sizeof(struct syspath), syspath_cmp);
@@ -258,7 +259,6 @@ struct udev_list_entry *udev_enumerate_get_list_entry(struct udev_enumerate *ude
 		max = udev_enumerate->devices_cur;
 		for (i = 0; i < max; i++) {
 			struct syspath *entry = &udev_enumerate->devices[i];
-			size_t move_later_prefix = 0;
 
 			/* skip duplicated entries */
 			if (prev != NULL &&

Re: [PATCH] fix for move_later in udev_enumerate_get_list_entry

[Kay Sievers]

On Mon, Dec 28, 2009 at 22:12, Thomas de Grenier de Latour
<tom.gl@free.fr> wrote:
> The attached patch fixes a bug in the udev_enumerate_get_list_entry()
> function of "libudev-enumerate.c".  The move_later_prefix variable was
> reset to zero on each loop iteration, and thus the move_later entry (if
> any) was not added right after changing to another syspath prefix, but
> rather after exiting the enumeration loop.

Applied.

Thanks,
Kay