On 02/07/2024 11:00, lijiang wrote: Cool, It sounds more better/accurate. " -r For a list linked with list_head structures, traverse the list", " in the reverse order by using the \"prev\" pointer instead", " of \"next\".", -r usage also says it's used for list_head structure. So implicitly enable LIST_HEAD_REVERSE is reasonable. Thanks Zhijian >                          ld->flags |= LIST_HEAD_REVERSE; >                         break; > >  Also let's see the following code: > >         if (ld->flags & LIST_HEAD_FORMAT) { >                 ld->list_head_offset = ld->member_offset; >                 if (ld->flags & LIST_HEAD_REVERSE) >                         ld->member_offset = sizeof(void *); >                 else >                         ld->member_offset = 0; > > Furthermore, the help page is: > SYNOPSIS >   list [[-o] offset][-e end][-[s|S] struct[.member[,member] [-l offset]] -[x|d]] >        [-r|-B] [-h [-O head_offset]|-H] start > > The '-r' looks like an optional option, just like '-h' and '-H'. > > Can you help double check? > > Thanks > Lianbo > > Add a further check to ensure -r is used in conjunction with -H or -h. > > Signed-off-by: Li Zhijian <lizhijian(a)fujitsu.com <mailto:lizhijian@fujitsu.com>> > --- >  help.c  | 3 ++- >  tools.c | 3 +++ >  2 files changed, 5 insertions(+), 1 deletion(-) > > diff --git a/help.c b/help.c > index d80e843703c1..6f7e093cbef1 100644 > --- a/help.c > +++ b/help.c > @@ -5977,7 +5977,8 @@ char *help__list[] = { >  " ", >  "           -x  Override the default output format with hexadecimal format.", >  "           -d  Override the default output format with decimal format.", > -"           -r  For a list linked with list_head structures, traverse the list", > +"           -r  Must be used in conjunction with either -H or -h.", > +"               For a list linked with list_head structures, traverse the list", >  "               in the reverse order by using the \"prev\" pointer instead", >  "               of \"next\".", >  "           -B  Use the algorithm from R. P. Brent to detect loops instead of", > diff --git a/tools.c b/tools.c > index 0f2db108838a..67977605c276 100644 > --- a/tools.c > +++ b/tools.c > @@ -3451,6 +3451,9 @@ cmd_list(void) >                 } >         } > > +       if (ld->flags & LIST_HEAD_REVERSE && !(ld->flags & LIST_HEAD_FORMAT)) > +               error(FATAL, "-r must be used in conjunction with -H or -h\n"); > + >         if (argerrs) >                 cmd_usage(pc->curcmd, SYNOPSIS); > > -- > 2.29.2 >