> -----Original Message----- > From: kernelnewbies-bounce@xxxxxxxxxxxx [mailto:kernelnewbies- > bounce@xxxxxxxxxxxx] On Behalf Of Srdjan Todorovic > Sent: Monday, February 19, 2007 2:06 PM > To: kernelnewbies@xxxxxxxxxxxx > Subject: list_entry() question > > Hello everyone. > > I'm converting some scsi driver to use the kernel list API, and have a > question regarding the list handling. > > The driver has several structs that represent the controllers, and > each controller has a list of work items. Suppose for example: > > struct host_controller { > int foo; > struct list_head the_list; > }; > The_list.next will _point_ to the head of the work item list. > struct work_item { > int blah; > void *zot; > struct list_head list_item; > }; > > Suppose I have 2 struct host_controllers, and 10 struct work_item per > controller. > > I walk the list of work items for a controller, using list_for_each() > and then I get the struct work_item variable using > list_entry(cursor, struct work_item, list_item); > > Now, from what I understand, the head of the list, the struct > host_controller variable, is in the list because its the_list is linked > with the rest of the struct list_head variables that make up the list. > > What happens when list_for_each() hits struct host_controller's the_list > variable? The list_for_each() will stop when it gets to the_list.prev, so this wont happen. I kinda see what youre saying, and I'm probably not explain this well but what your asking is not going to happen. Every item you walk with list_for_each() will be of struct type work_item. > What happens when list_entry() tries to get me a struct work_item when in > reality the current struct list_head variable is in struct > host_controller? It wont happen. LDD explains this well I think. http://lwn.net/Kernel/LDD3/ see chapter 11. -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
