core/device: rewrite how device unit is removed from Manager.devices_by_sysfs

If the device unit is not the head of the list saved in
Manager.devices_by_sysfs, then it is not necessary to replace the
existing hashmap entry. This should not change any behavior, just
refactoring.

1 files changed, 14 insertions, 7 deletions

diff --git a/src/core/device.c b/src/core/device.c
index 4f6ecf4d7f..1449867e35 100644
--- a/src/core/device.c
+++ b/src/core/device.c
@@ -55,24 +55,31 @@ static int device_by_path(Manager *m, const char *path, Unit **ret) {
 
 static void device_unset_sysfs(Device *d) {
         Hashmap *devices;
-        Device *first;
 
         assert(d);
 
         if (!d->sysfs)
                 return;
 
-        /* Remove this unit from the chain of devices which share the
-         * same sysfs path. */
+        /* Remove this unit from the chain of devices which share the same sysfs path. */
+
         devices = UNIT(d)->manager->devices_by_sysfs;
-        first = hashmap_get(devices, d->sysfs);
-        LIST_REMOVE(same_sysfs, first, d);
 
-        if (first)
-                hashmap_remove_and_replace(devices, d->sysfs, first->sysfs, first);
+        if (d->same_sysfs_prev)
+                /* If this is not the first unit, then simply remove this unit. */
+                d->same_sysfs_prev->same_sysfs_next = d->same_sysfs_next;
+        else if (d->same_sysfs_next)
+                /* If this is the first unit, replace with the next unit. */
+                assert_se(hashmap_replace(devices, d->same_sysfs_next->sysfs, d->same_sysfs_next) >= 0);
         else
+                /* Otherwise, remove the entry. */
                 hashmap_remove(devices, d->sysfs);
 
+        if (d->same_sysfs_next)
+                d->same_sysfs_next->same_sysfs_prev = d->same_sysfs_prev;
+
+        d->same_sysfs_prev = d->same_sysfs_next = NULL;
+
         d->sysfs = mfree(d->sysfs);
 }