Re: [Crash-utility] Adding a new command rbtree

----- Original Message ----- > At 2012-5-22 23:15, Dave Anderson wrote: >> Doing it that way really confuses two different "offset" issues that are associated >> with this command: >> >> (1) the offset of an rb_root or radix_tree_node within a containing >> data structure, and >> (2) the offset of an rb_node within a containing data structure. >> >> And in both cases, forget trying to implement the "the -o is not necessary" and >> "the -o is only necessary..." optimizations, because it would be almost impossible >> to do. > > Hello Dave, > > I will list all the situations I was concerning. > > First red-black tree: > 1. rb_node is embedded in a structure. Address is the address of the > structure, and -o shows the offset of rb_node to the structure. > > 2. same as 1., but the address is the address of rb_node when using -N > in command line. > > rb_root was not concering. I will recall the reason. I can get the root > node from rb_root. And then the offspring of the root node. Then I still > need a offset that shows the offset of the offspring node to its related > structure to get the structure's information. > > Then radix tree: > 3. radix_tree_root's address is specified. > > 4. radix_tree_node's address is specified. > > According to your reply, "-r offset" indicates rb_root and radix_tree_root, Correct, but only if the rb_root or radix_tree_root are embedded in a data structure, and the address argument points to the data stucture. > and "-n offset" indicates rb_node and radix_tree_node. No -- the "-n offset" would only applicable to rb_nodes. radix_tree_node structures data are standalone entities that are allocated from the "radix_tree_node" slab cache, correct? When would a radix_tree_node ever be embedded in a containing data structure? > And if I use "-r offset", then I need another option to show the offset > of rb_node. And when using "-n offset" together with an address, which > can only be one of rb_node's address and address of the structure > rb_node embedded in, I may need another option to indicate the address's > type. The address is either that of an rb_root or radix_tree_root, or the address of the containing data structure, in which case it would require the "-r offset" option. > > So I think "tree -t type -r offset -n offset -m addr..." is a good > choice. "-r offset" indicates the rb_root or radix_tree_root's offset, > and "-n offset" indicates the rb_node or radix_tree_node's offset. Again, what is a "radix_tree_node offset"? > only using "-n offset" indicates the addr is related to rb_node or > radix_tree_node, but if "-r offset" is also specified, the addr is > related to rb_root or radix_tree_root. When "-m" is specified, the addr > is the address of the root(when specified "-r offset") or the node. If > "-m" is not specified, the addr is the address of the structure that > containing the root(when specified "-r offset") or the node. > > Do you think it's OK? No, that confuses the hell out me... I really don't understand the need for the additional "-m" option? To me it's simple -- but I may be missing something. The address argument can be either: (1) A pointer to an rb_root or radix_tree_root. The "-r offset" is not required. (2) A pointer to a data structure containing an rb_root or radix_tree_root. The "-r offset" option is required if the member offset is non-zero. That being the case, this should work: red-black tree: tree -t type [-r offset] [-n offset] address radix tree: tree -t type [-r offset] address In the case of a red-black tree, it seems that you are also trying to support the bypassing of the rb_root entirely, and point to an rb_node directly? That would seem to be an odd-ball case, because the list would be truncated if you don't point to the topmost rb_node. Is that what you have in mind? If so, I suppose that you could also have a additional "-N" option or something like that to signal that the address argument is a pointer to an rb_node (and not applicable to radix trees).

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