From 9c68b5675ffd11f2a3f9123446b54c2d0eea4682 Mon Sep 17 00:00:00 2001 From: Yu Watanabe Date: Wed, 1 Sep 2021 04:16:21 +0900 Subject: [PATCH] udev-node: save information about device node and priority in symlink Previously, we only store device IDs in /run/udev/links, and when creating/removing device node symlink, we create sd_device object corresponds to the IDs and read device node and priority from the object. That requires parsing uevent and udev database files. This makes link_find_prioritized() get the most prioritzed device node without parsing the files. (cherry picked from commit 377a83f0d80376456d9be203796f66f543a8b943) Related: #1977994 --- src/udev/udev-node.c | 172 ++++++++++++++++++++++++++++++------------- 1 file changed, 121 insertions(+), 51 deletions(-) diff --git a/src/udev/udev-node.c b/src/udev/udev-node.c index 4496a2bd9b..5d6aae0bd4 100644 --- a/src/udev/udev-node.c +++ b/src/udev/udev-node.c @@ -18,6 +18,7 @@ #include "fs-util.h" #include "hexdecoct.h" #include "mkdir.h" +#include "parse-util.h" #include "path-util.h" #include "selinux-util.h" #include "smack-util.h" @@ -28,9 +29,9 @@ #include "udev-node.h" #include "user-util.h" -#define CREATE_LINK_MAX_RETRIES 128 -#define LINK_UPDATE_MAX_RETRIES 128 -#define TOUCH_FILE_MAX_RETRIES 128 +#define CREATE_LINK_MAX_RETRIES 128 +#define LINK_UPDATE_MAX_RETRIES 128 +#define CREATE_STACK_LINK_MAX_RETRIES 128 #define UDEV_NODE_HASH_KEY SD_ID128_MAKE(b9,6a,f1,ce,40,31,44,1a,9e,19,ec,8b,ae,f3,e3,2f) static int create_symlink(const char *target, const char *slink) { @@ -175,39 +176,67 @@ static int link_find_prioritized(sd_device *dev, bool add, const char *stackdir, return r; FOREACH_DIRENT_ALL(dent, dir, break) { - _cleanup_(sd_device_unrefp) sd_device *dev_db = NULL; - const char *devnode; - int db_prio = 0; + _cleanup_free_ char *path = NULL, *buf = NULL; + int tmp_prio; - if (dent->d_name[0] == '\0') - break; if (dent->d_name[0] == '.') continue; - log_device_debug(dev, "Found '%s' claiming '%s'", dent->d_name, stackdir); - - /* did we find ourself? */ + /* skip ourself */ if (streq(dent->d_name, id)) continue; - if (sd_device_new_from_device_id(&dev_db, dent->d_name) < 0) - continue; + path = path_join(stackdir, dent->d_name); + if (!path) + return -ENOMEM; - if (sd_device_get_devname(dev_db, &devnode) < 0) - continue; + if (readlink_malloc(path, &buf) >= 0) { + char *devnode; - if (device_get_devlink_priority(dev_db, &db_prio) < 0) - continue; + /* New format. The devnode and priority can be obtained from symlink. */ - if (target && db_prio <= priority) - continue; + devnode = strchr(buf, ':'); + if (!devnode || devnode == buf) + continue; - log_device_debug(dev_db, "Device claims priority %i for '%s'", db_prio, stackdir); + *(devnode++) = '\0'; + if (!path_startswith(devnode, "/dev")) + continue; - r = free_and_strdup(&target, devnode); - if (r < 0) - return r; - priority = db_prio; + if (safe_atoi(buf, &tmp_prio) < 0) + continue; + + if (target && tmp_prio <= priority) + continue; + + r = free_and_strdup(&target, devnode); + if (r < 0) + return r; + } else { + _cleanup_(sd_device_unrefp) sd_device *tmp_dev = NULL; + const char *devnode; + + /* Old format. The devnode and priority must be obtained from uevent and + * udev database files. */ + + if (sd_device_new_from_device_id(&tmp_dev, dent->d_name) < 0) + continue; + + if (device_get_devlink_priority(tmp_dev, &tmp_prio) < 0) + continue; + + if (target && tmp_prio <= priority) + continue; + + if (sd_device_get_devname(tmp_dev, &devnode) < 0) + continue; + + r = free_and_strdup(&target, devnode); + if (r < 0) + return r; + } + + priority = tmp_prio; } *ret = TAKE_PTR(target); @@ -256,10 +285,72 @@ toolong: return size - 1; } +static int update_stack_directory(sd_device *dev, const char *dirname, bool add) { + _cleanup_free_ char *filename = NULL, *data = NULL, *buf = NULL; + const char *devname, *id; + int priority, r; + + assert(dev); + assert(dirname); + + r = device_get_device_id(dev, &id); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to get device id: %m"); + + filename = path_join(dirname, id); + if (!filename) + return log_oom_debug(); + + if (!add) { + if (unlink(filename) < 0 && errno != ENOENT) + log_device_debug_errno(dev, errno, "Failed to remove %s, ignoring: %m", filename); + + (void) rmdir(dirname); + return 0; + } + + r = sd_device_get_devname(dev, &devname); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to get device node: %m"); + + r = device_get_devlink_priority(dev, &priority); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to get priority of device node symlink: %m"); + + if (asprintf(&data, "%i:%s", priority, devname) < 0) + return log_oom_debug(); + + if (readlink_malloc(filename, &buf) >= 0 && streq(buf, data)) + return 0; + + if (unlink(filename) < 0 && errno != ENOENT) + log_device_debug_errno(dev, errno, "Failed to remove %s, ignoring: %m", filename); + + for (unsigned j = 0; j < CREATE_STACK_LINK_MAX_RETRIES; j++) { + /* This may fail with -ENOENT when the parent directory is removed during + * creating the file by another udevd worker. */ + r = mkdir_p(dirname, 0755); + if (r == -ENOENT) + continue; + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to create directory %s: %m", dirname); + + if (symlink(data, filename) < 0) { + if (errno == ENOENT) + continue; + return log_device_debug_errno(dev, errno, "Failed to create symbolic link %s: %m", filename); + } + + return 0; + } + + return log_device_debug_errno(dev, SYNTHETIC_ERRNO(ELOOP), "Failed to create symbolic link %s: %m", filename); +} + /* manage "stack of names" with possibly specified device priorities */ static int link_update(sd_device *dev, const char *slink_in, bool add) { - _cleanup_free_ char *slink = NULL, *filename = NULL, *dirname = NULL; - const char *slink_name, *id; + _cleanup_free_ char *slink = NULL, *dirname = NULL; + const char *slink_name; char name_enc[NAME_MAX+1]; int i, r, retries; @@ -279,35 +370,14 @@ static int link_update(sd_device *dev, const char *slink_in, bool add) { return log_device_debug_errno(dev, SYNTHETIC_ERRNO(EINVAL), "Invalid symbolic link of device node: %s", slink); - r = device_get_device_id(dev, &id); - if (r < 0) - return log_device_debug_errno(dev, r, "Failed to get device id: %m"); - (void) udev_node_escape_path(slink_name, name_enc, sizeof(name_enc)); - dirname = path_join("/run/udev/links/", name_enc); + dirname = path_join("/run/udev/links", name_enc); if (!dirname) return log_oom_debug(); - filename = path_join(dirname, id); - if (!filename) - return log_oom_debug(); - - if (!add) { - if (unlink(filename) < 0 && errno != ENOENT) - log_device_debug_errno(dev, errno, "Failed to remove %s, ignoring: %m", filename); - - (void) rmdir(dirname); - } else { - for (unsigned j = 0; j < TOUCH_FILE_MAX_RETRIES; j++) { - /* This may fail with -ENOENT when the parent directory is removed during - * creating the file by another udevd worker. */ - r = touch_file(filename, /* parents= */ true, USEC_INFINITY, UID_INVALID, GID_INVALID, 0444); - if (r != -ENOENT) - break; - } - if (r < 0) - return log_device_debug_errno(dev, r, "Failed to create %s: %m", filename); - } + r = update_stack_directory(dev, dirname, add); + if (r < 0) + return r; /* If the database entry is not written yet we will just do one iteration and possibly wrong symlink * will be fixed in the second invocation. */