At 2012-6-7 21:39, Dave Anderson wrote:
I think the -h description should state that the address is a pointer to
a "data structure containing a list_head". The "next" sentence probably
doesn't belong there, because it's pretty much repeating the list_head
related discussion above in help page's number "2" section. And
there should probably be a caveat re: the fact that there may be
a bogus structure address shown in the case of an external LIST_HEAD()
or a starting list_head that's in a different data structure entirely.
And most importantly, a simple but clear example should be shown.
Hello Dave,
I made some modification to help__list. Is it suitable to describe the
function of "-h" option?
--
--
Regards
Qiao Nuohan
diff --git a/help.c b/help.c
index af165e8..3db8fe3 100755
--- a/help.c
+++ b/help.c
@@ -4372,37 +4372,49 @@ NULL
char *help__list[] = {
"list",
"linked list",
-"[[-o] offset] [-e end] [-s struct[.member[,member]] -[xd]] [-H] start",
+"[[-o] offset] [-e end] [-s struct[.member[,member]] -[xd]] [-h|-H] start",
" This command dumps the contents of a linked list. The entries in a linked",
" list are typically data structures that are tied together in one of two",
" formats:",
" ",
" 1. A starting address points to a data structure; that structure contains",
-" a member that is a pointer to the next structure, and so on. The list",
-" typically ends when a \"next\" pointer value contains one of the",
-" following:\n",
+" a member that is a pointer to the next structure, and so on. If \"list\"",
+" command is used to dump such type of linked list, \"-h\" or \"-H\" should",
+" not be pre-pended before \"start\" argument. The list typically ends when",
+" a \"next\" pointer value contains one of the following:\n",
" a. a NULL pointer.",
" b. a pointer to the start address.",
" c. a pointer to the first item pointed to by the start address.",
" d. a pointer to its containing structure.",
" ",
" 2. Most Linux lists are linked via embedded list_head structures contained ",
-" within the data structures in the list. The linked list is headed by an",
-" external LIST_HEAD, which is simply a list_head structure initialized to",
-" point to itself, signifying that the list is empty:",
+" within the data structures in the list.",
" ",
" struct list_head {",
" struct list_head *next, *prev;",
" };",
" ",
-" #define LIST_HEAD_INIT(name) { &(name), &(name) }"
-" ",
-" #define LIST_HEAD(name) struct list_head name = LIST_HEAD_INIT(name)",
-" ",
" In the case of list_head-type lists, the \"next\" pointer is the address",
" of the embedded list_head structure in the next structure, and not the",
-" address of the structure itself. The list typically ends when the",
-" list_head's next pointer points back to the LIST_HEAD address.",
+" address of the structure itself. \"-h\" or \"-H\" be used to indicate",
+" such type of list:\n",
+" a. \"-h\" is used to indicate the \"start\" argument is the address of",
+" the structure which contains the structure list_head. The list",
+" typically ends when the list_head's next pointer points back to the",
+" embedded list_head contained in the structure whose address is",
+" offered by \"start\" argument",
+" b. \"-H\" is used to indicate the \"start\" argument is the address of",
+" LIST_HEAD. The linked list can be headed by an external LIST_HEAD,",
+" which is simply a list_head structure initialized to point to itself,",
+" signifying that the list is empty:",
+" ",
+" #define LIST_HEAD_INIT(name) { &(name), &(name) }"
+" ",
+" #define LIST_HEAD(name) struct list_head name = LIST_HEAD_INIT(name)",
+" ",
+" If \"start\" argument is the address of such list_head structure,",
+" \"-H\" is needed. The list typically ends when the list_head's next",
+" pointer points back to the LIST_HEAD address.",
" ",
" This command can handle both types of linked list; in both cases the list",
" of addresses that are dumped are the addresses of the data structures",
@@ -4427,10 +4439,11 @@ char *help__list[] = {
" -d override default output format with decimal format.",
" ",
" The meaning of the \"start\" argument, which can be expressed either",
-" symbolically or in hexadecimal format, depends upon whether the -H option",
+" symbolically or in hexadecimal format, depends upon whether the -h/-H option",
" is pre-pended or not:",
" ",
" start The address of the first structure in the list.",
+" -h start The address of the structure which contains the embeded list_head",
" -H start The address of the list_head structure, typically expressed",
" symbolically, but also can be an expression evaluating to the",
" address of the starting list_head structure.",
@@ -4555,7 +4568,7 @@ char *help__list[] = {
" f7254000",
" f7004000",
" ",
-" Lastly, in some kernel versions, the vfsmount structures of the mounted",
+" In some kernel versions, the vfsmount structures of the mounted",
" filesystems are linked by the LIST_HEAD \"vfsmntlist\", which uses the",
" mnt_list list_head of each vfsmount structure in the list. To dump each",
" vfsmount structure in the list, append the -s option:\n",
@@ -4596,6 +4609,35 @@ char *help__list[] = {
" f7445f60",
" struct vfsmount {",
" ...",
+" Structure task_struct is linked by a embedded \"tasks\". To dump all linked",
+" task_struct, using \"-h\" option:\n"
+" %s> list task_struct.tasks -s task_struct.tasks -h ffff88004b56ca80",
+" ffff88004b56ca80",
+" tasks = {",
+" next = 0xffffffff81a8d468, ",
+" prev = 0xffff88004b56d908",
+" }",
+" ffffffff81a8d020",
+" tasks = {",
+" next = 0xffff88004eac3908, ",
+" prev = 0xffff88004b56cec8",
+" }",
+" ffff88004eac34c0",
+" tasks = {",
+" next = 0xffff88004eac2ec8, ",
+" prev = 0xffffffff81a8d468",
+" }",
+" ...",
+" ffff88004b62a0c0",
+" tasks = {",
+" next = 0xffff88004b56d908, ",
+" prev = 0xffff88004b62af48",
+" }",
+" ffff88004b56d4c0",
+" tasks = {",
+" next = 0xffff88004b56cec8, ",
+" prev = 0xffff88004b62a508",
+" }",
NULL
};
--
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