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authorKay Sievers <kay.sievers@vrfy.org>2010-05-05 11:14:50 +0200
committerKay Sievers <kay.sievers@vrfy.org>2010-05-05 11:39:25 +0200
commit75cb1ac51ea0176926c749bd0f22c19ce8b20e5f (patch)
tree7d813ccdbe7385c4b69b0a3507ffae6f3f7a7bb2
parent2d01980f1afbde8aabd175a5d866a8eeccc29208 (diff)
warn when renaming kernel-provided nodes instead of adding symlinks
-rw-r--r--NEWS11
-rwxr-xr-xtest/udev-test.pl11
-rw-r--r--udev/udev-event.c27
-rw-r--r--udev/udev-rules.c10
-rw-r--r--udev/udev.xml91
5 files changed, 72 insertions, 78 deletions
diff --git a/NEWS b/NEWS
index f3163ecd7e..d4e8477cfb 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,16 @@
udev 154
========
+Bugfixes.
+
+Udev now gradually starts to pass control over the primary device nodes
+and their names to the kernel, and will in the end only manage the
+permissions of the node, and possibly create additional symlinks.
+As a first step NAME="" will be ignored, and NAME= setings with names
+other than the kernel provided name will result in a logged warning.
+Kernels that don't provide device names, or devtmpfs is not used, will
+still work as they did before, but it is strongly recommended to use
+only the same names for the primary device node as the recent kernel
+provides for all devices.
udev 153
========
diff --git a/test/udev-test.pl b/test/udev-test.pl
index a4d3a728f7..24e62b4d66 100755
--- a/test/udev-test.pl
+++ b/test/udev-test.pl
@@ -1266,17 +1266,6 @@ KERNEL=="ttyACM[0-9]*", SYMLINK="three"
EOF
},
{
- desc => "test empty NAME",
- subsys => "tty",
- devpath => "/devices/pci0000:00/0000:00:1d.7/usb5/5-2/5-2:1.0/tty/ttyACM0",
- exp_name => "<none>",
- not_exp_name => "ttyACM0",
- exp_add_error => "yes",
- rules => <<EOF
-KERNEL=="ttyACM[0-9]*", NAME=""
-EOF
- },
- {
desc => "test empty SYMLINK+ (empty override)",
subsys => "tty",
devpath => "/devices/pci0000:00/0000:00:1d.7/usb5/5-2/5-2:1.0/tty/ttyACM0",
diff --git a/udev/udev-event.c b/udev/udev-event.c
index 1e7a2ea34c..1be3f74ea3 100644
--- a/udev/udev-event.c
+++ b/udev/udev-event.c
@@ -617,15 +617,20 @@ int udev_event_execute_rules(struct udev_event *event, struct udev_rules *rules)
}
}
- if (event->name == NULL) {
- /* things went wrong */
+ if (event->name == NULL || event->name[0] == '\0') {
udev_device_delete_db(dev);
udev_device_tag_index(dev, NULL, false);
udev_device_unref(event->dev_db);
err = -ENOMEM;
+ err(event->udev, "no node name, something went wrong, ignoring\n");
goto out;
}
+ if (udev_device_get_knodename(dev) != NULL && strcmp(udev_device_get_knodename(dev), event->name) != 0)
+ err(event->udev, "kernel-provided name '%s' and NAME= '%s' disagree, "
+ "please use SYMLINK+= or change the kernel to provide the proper name\n",
+ udev_device_get_knodename(dev), event->name);
+
/* set device node name */
util_strscpyl(filename, sizeof(filename), udev_get_dev_path(event->udev), "/", event->name, NULL);
udev_device_set_devnode(dev, filename);
@@ -639,23 +644,7 @@ int udev_event_execute_rules(struct udev_event *event, struct udev_rules *rules)
if (event->dev_db != NULL)
udev_node_update_old_links(dev, event->dev_db);
- if (event->name[0] != '\0')
- err = udev_node_add(dev, event->mode, event->uid, event->gid);
- else
- info(event->udev, "device node creation suppressed\n");
-
- /* remove kernel-created node, if needed */
- if (udev_device_get_knodename(dev) != NULL && strcmp(event->name, udev_device_get_knodename(dev)) != 0) {
- struct stat stats;
- char filename[UTIL_PATH_SIZE];
-
- util_strscpyl(filename, sizeof(filename), udev_get_dev_path(event->udev), "/", udev_device_get_knodename(dev), NULL);
- if (lstat(filename, &stats) == 0 && stats.st_rdev == udev_device_get_devnum(dev)) {
- info(event->udev, "remove kernel created node '%s'\n", udev_device_get_knodename(dev));
- util_unlink_secure(event->udev, filename);
- util_delete_path(event->udev, filename);
- }
- }
+ err = udev_node_add(dev, event->mode, event->uid, event->gid);
}
udev_device_unref(event->dev_db);
diff --git a/udev/udev-rules.c b/udev/udev-rules.c
index eb73221fa9..59fdb71853 100644
--- a/udev/udev-rules.c
+++ b/udev/udev-rules.c
@@ -1468,9 +1468,13 @@ static int add_rule(struct udev_rules *rules, char *line,
if (op < OP_MATCH_MAX) {
rule_add_key(&rule_tmp, TK_M_NAME, op, value, NULL);
} else {
- if (strcmp(value, "%k") == 0)
- err(rules->udev, "NAME=\"%%k\" is superfluous and breaks "
- "kernel supplied names, please remove it from %s:%u\n", filename, lineno);
+ if (strcmp(value, "%k") == 0) {
+ err(rules->udev, "NAME=\"%%k\" is ignored because it breaks kernel supplied names, "
+ "please remove it from %s:%u\n", filename, lineno);
+ continue;
+ }
+ if (value[0] == '\0')
+ continue;
rule_add_key(&rule_tmp, TK_A_NAME, op, value, NULL);
}
rule_tmp.rule.rule.flags = 1;
diff --git a/udev/udev.xml b/udev/udev.xml
index d2277c93d0..678023c373 100644
--- a/udev/udev.xml
+++ b/udev/udev.xml
@@ -18,23 +18,28 @@
<refnamediv>
<refname>udev</refname>
- <refpurpose>dynamic device management</refpurpose>
+ <refpurpose>Linux dynamic device management</refpurpose>
</refnamediv>
<refsect1><title>DESCRIPTION</title>
- <para>udev provides a dynamic device directory containing only the files for
- actually present devices. It creates or removes device node files in the
- <filename>/dev</filename> directory, or it renames network interfaces.</para>
-
- <para>Usually udev runs as <citerefentry><refentrytitle>udevd</refentrytitle>
- <manvolnum>8</manvolnum></citerefentry> and receives uevents directly from the
- kernel if a device is added or removed from the system.</para>
-
- <para>If udev receives a device event, it matches its configured rules
- against the available device attributes provided in sysfs to identify the device.
- Rules that match may provide additional device information or specify a device
- node name and multiple symlink names and instruct udev to run additional programs
- as part of the device event handling.</para>
+ <para>udev supplies the system software with device events, manages permissions
+ of device nodes and may create additional symlinks in the <filename>/dev</filename>
+ directory, or renames network interfaces. The kernel usually just assigns unpredictable
+ device names based on the order of discovery. Meaningful symlinks or network device
+ names provide a way to reliably identify devices based on their properties or
+ current configuration.</para>
+
+ <para>The udev daemon <citerefentry><refentrytitle>udevd</refentrytitle>
+ <manvolnum>8</manvolnum></citerefentry> receives device uevents directly from
+ the kernel whenever a device is added or removed from the system, or it changes its
+ state. When udev receives a device event, it matches its configured set of rules
+ against various device attributes to identify the device. Rules that match, may
+ provide additional device information to be stored in the udev database, or information
+ to be used to create meaningful symlink names.</para>
+
+ <para>All device information udev processes, is stored in the udev database and
+ sent out to possible event subscribers. Access to all stored data and the event
+ sources are provided by the library libudev.</para>
</refsect1>
<refsect1><title>CONFIGURATION</title>
@@ -84,9 +89,9 @@
If all match keys are matching against its value, the rule gets applied and the
assign keys get the specified value assigned.</para>
- <para>A matching rule may specify the name of the device node, add a symlink
- pointing to the node, or run a specified program as part of the event handling.
- If no matching rule is found, the default device node name is used.</para>
+ <para>A matching rule may rename a network interface, add symlinks
+ pointing to the device node, or run a specified program as part of
+ the event handling.</para>
<para>A rule consists of a list of one or more key value pairs separated by
a comma. Each key has a distinct operation, depending on the used operator. Valid
@@ -304,13 +309,17 @@
<varlistentry>
<term><option>NAME</option></term>
<listitem>
- <para>The name, a network interface should be renamed to, or the name
- a device node should be named. Usually the kernel provides the defined
- node name, or even creates and removes the node before udev receives
- any event. Changing the node name from the kernel's default may result
- in unexpected behavior and is not supported. Udev is only expected to
- handle device node permissions and to create additional symlinks, which
- do not conflict with the kernel device node names.</para>
+ <para>The name, a network interface should be renamed to. Or as
+ a temporary workaraound, the name a device node should be named.
+ Usually the kernel provides the defined node name, or even creates
+ and removes the node before udev even receives any event. Changing
+ the node name from the kernel's default creates inconsistencies
+ and is not supported. If the kernel and NAME specify different names,
+ an error will be logged. Udev is only expected to handle device node
+ permissions and to create additional symlinks, not to change
+ kernel-provided device node names. Instead of renaming a device node,
+ SYMLINK should be used. Symlink names must never conflict with
+ device node names, it will result in unpredictable behavior.</para>
</listitem>
</varlistentry>
@@ -318,15 +327,15 @@
<term><option>SYMLINK</option></term>
<listitem>
<para>The name of a symlink targeting the node. Every matching rule will add
- this value to the list of symlinks to be created along with the device node.
- Multiple symlinks may be specified by separating the names by the space
- character. In case multiple devices claim the same name, the link will
- always point to the device with the highest link_priority. If the current device
- goes away, the links will be re-evaluated and the device with the next highest
- link_priority will own the link. If no link_priority is specified, the order
- of the devices, and which of them will own the link, is undefined. Claiming
- the same name for a node and links may result in unexpected behavior and is
- not supported.
+ this value to the list of symlinks to be created. Multiple symlinks may be
+ specified by separating the names by the space character. In case multiple
+ devices claim the same name, the link will always point to the device with
+ the highest link_priority. If the current device goes away, the links will
+ be re-evaluated and the device with the next highest link_priority will own
+ the link. If no link_priority is specified, the order of the devices, and
+ which one of them will own the link, is undefined. Claiming the same name for
+ a symlink, which is or might be used for a device node, may result in
+ unexpected behavior and is not supported.
</para>
</listitem>
</varlistentry>
@@ -379,18 +388,10 @@
<option>RUN{<replaceable>fail_event_on_error</replaceable>}</option> is
specified, and the executed program returns non-zero, the event will be
marked as failed for a possible later handling.</para>
- <para>If no path is given, the program must be in
- <filename>/lib/udev</filename>, otherwise the full path must be
- specified.</para>
- <para>If the specified string starts with
- <option>socket:<replaceable>path</replaceable></option>, all current event
- values will be passed to the specified socket, as a message in the same
- format the kernel sends an uevent. If the first character of the specified path
- is an @ character, an abstract namespace socket is used, instead of an existing
- socket file.</para>
- <para>Program name and arguments are separated with spaces. To
- include spaces in an argument, use single quotes. Please note
- that this does not run through a shell.</para>
+ <para>If no absolute path is given, the program is expected to live in
+ <filename>/lib/udev</filename>, otherwise the absolute path must be
+ specified. Program name and arguments are separated by spaces. Single quotes
+ can be used to specify arguments with spaces.</para>
</listitem>
</varlistentry>