The 05/18/2021 07:39, HAGIO KAZUHITO(萩尾 一仁) wrote:
Hi Kazu,
> Hi Firo,
>
> sorry for the late reply.
>
> -----Original Message-----
> > This new O option is very useful to specify the head node
> > offset for listing linked list whose head node embedded has a
> > different offset to other node, e.g. dentry.d_subdirs(the head node)
> > and dentry.d_child.
> >
> > Signed-off-by: Firo Yang <firo.yang@xxxxxxxx>
> > ---
> > defs.h | 1 +
> > help.c | 12 +++++++++++-
> > tools.c | 30 +++++++++++++++++++++++++++---
> > 3 files changed, 39 insertions(+), 4 deletions(-)
> >
> > diff --git a/defs.h b/defs.h
> > index 35b983a..764facf 100644
> > --- a/defs.h
> > +++ b/defs.h
> > @@ -2605,6 +2605,7 @@ struct list_data { /* generic structure used by do_list() to walk */
> > #define LIST_PARSE_MEMBER (VERBOSE << 13)
> > #define LIST_READ_MEMBER (VERBOSE << 14)
> > #define LIST_BRENT_ALGO (VERBOSE << 15)
> > +#define LIST_HEAD_OFFSET_ENTERED (VERBOSE << 16)
> >
> > struct tree_data {
> > ulong flags;
> > diff --git a/help.c b/help.c
> > index 531f50a..b561f3b 100644
> > --- a/help.c
> > +++ b/help.c
> > @@ -5716,7 +5716,7 @@ char *help__list[] = {
> > "list",
> > "linked list",
> > "[[-o] offset][-e end][-[s|S] struct[.member[,member] [-l offset]] -[x|d]]"
> > -"\n [-r|-B] [-h|-H] start",
> > +"\n [-r|-B] [-h [-O head_offset]|-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",
> > @@ -5800,6 +5800,16 @@ char *help__list[] = {
> > " -S struct Similar to -s, but instead of parsing gdb output, member values",
> > " are read directly from memory, so the command works much faster",
> > " for 1-, 2-, 4-, and 8-byte members.",
> > +" -O offset The -O option works only with -h option.",
> > +" It is used for specifying the offset of head node embedded in a",
> > +" structure, like dentry.d_subdirs or cgroup_subsys_state.children.",
>
> Could I have an example usage of dentry.d_subdirs case with and without
> the patch?
>
> I'd like to add that to the EXAMPLES section, instead of adding the
> specific member names here.
Sure, I will update the patch.
>
> Also, can it detect the end of list correctly with the patch?
You are right. It can not detect the end of list correctly; I will fix
it in V2.
>
> > +" The offset may be entered in either of two manners:",
> > +"",
> > +" 1. \"structure.member\" format.",
> > +" 2. a number of bytes.",
> > +"",
> > +" You can use it like the following:",
> > +" list -O <head node offset> -o <node offset> -h start -s <...>",
> > " -l offset Only used in conjunction with -s, if the start address argument",
> > " is a pointer to an embedded list head (or any other similar list",
> > " linkage structure whose first member points to the next linkage",
> > diff --git a/tools.c b/tools.c
> > index a26b101..792a567 100644
> > --- a/tools.c
> > +++ b/tools.c
> > @@ -3343,6 +3343,7 @@ void
> > cmd_list(void)
> > {
> > int c;
> > + long head_member_offset; /* offset for head like denty.d_subdirs */
>
> This warning is emitted:
>
> cc -c -g -DX86_64 -DLZO -DSNAPPY -DGDB_7_6 tools.c -Wall -O2 -Wstrict-prototypes -Wmissing-prototypes -fstack-protector -Wformat-security
> tools.c: In function ‘cmd_list’:
> tools.c:3400:37: warning: ‘head_member_offset’ may be used uninitialized in this function [-Wmaybe-uninitialized]
> error(FATAL,
> ^
OK. I will assign a initial vaule to head_member_offset.
>
> Thanks,
> Kazu
>
> > struct list_data list_data, *ld;
> > struct datatype_member struct_member, *sm;
> > struct syment *sp;
> > @@ -3353,7 +3354,7 @@ cmd_list(void)
> > BZERO(ld, sizeof(struct list_data));
> > struct_list_offset = 0;
> >
> > - while ((c = getopt(argcnt, args, "BHhrs:S:e:o:xdl:")) != EOF) {
> > + while ((c = getopt(argcnt, args, "BHhrs:S:e:o:O:xdl:")) != EOF) {
> > switch(c)
> > {
> > case 'B':
> > @@ -3394,6 +3395,24 @@ cmd_list(void)
> > optarg);
> > break;
> >
> > + case 'O':
> > + if (ld->flags & LIST_HEAD_OFFSET_ENTERED)
> > + error(FATAL,
> > + "offset value %d (0x%lx) already entered\n",
> > + head_member_offset, head_member_offset);
> > + else if (IS_A_NUMBER(optarg))
> > + head_member_offset = stol(optarg,
> > + FAULT_ON_ERROR, NULL);
> > + else if (arg_to_datatype(optarg,
> > + sm, RETURN_ON_ERROR) > 1)
> > + head_member_offset = sm->member_offset;
> > + else
> > + error(FATAL, "invalid -O argument: %s\n",
> > + optarg);
> > +
> > + ld->flags |= LIST_HEAD_OFFSET_ENTERED;
> > + break;
> > +
> > case 'o':
> > if (ld->flags & LIST_OFFSET_ENTERED)
> > error(FATAL,
> > @@ -3599,8 +3618,13 @@ next_arg:
> > fprintf(fp, "(empty)\n");
> > return;
> > }
> > - } else
> > - ld->start += ld->list_head_offset;
> > + } else {
> > + if (ld->flags & LIST_HEAD_OFFSET_ENTERED)
> > + readmem(ld->start + head_member_offset, KVADDR,
> > + &ld->start, sizeof(void *), "LIST_HEAD contents", FAULT_ON_ERROR);
> > + else
> > + ld->start += ld->list_head_offset;
> > + }
> > }
> >
> > ld->flags &= ~(LIST_OFFSET_ENTERED|LIST_START_ENTERED);
> > --
> > 2.30.2
> >
> >
> > --
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> > Crash-utility@xxxxxxxxxx
> > https://listman.redhat.com/mailman/listinfo/crash-utility
>
>
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