linux-kernel - Re: [PATCH v2] kdb: Simplify kdb commands registration

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Message-ID: <CAFA6WYMZEU3Sme0GH16i+QHv3uhzSevjpEMzfY8trKvT_gV_Hw@mail.gmail.com>
Date:   Thu, 28 Jan 2021 10:42:18 +0530
From:   Sumit Garg <sumit.garg@...aro.org>
To:     Doug Anderson <dianders@...omium.org>
Cc:     kgdb-bugreport@...ts.sourceforge.net,
        Jason Wessel <jason.wessel@...driver.com>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] kdb: Simplify kdb commands registration

On Mon, 25 Jan 2021 at 21:32, Doug Anderson <dianders@...omium.org> wrote:
>
> Hi,
>
> On Sun, Jan 24, 2021 at 11:06 PM Sumit Garg <sumit.garg@...aro.org> wrote:
> >
> > Simplify kdb commands registration via using linked list instead of
> > static array for commands storage.
> >
> > Signed-off-by: Sumit Garg <sumit.garg@...aro.org>
> > ---
> >
> > Changes in v2:
> > - Remove redundant NULL check for "cmd_name".
> > - Incorporate misc. comment.
> >
> >  kernel/debug/kdb/kdb_main.c    | 119 ++++++++++++-----------------------------
> >  kernel/debug/kdb/kdb_private.h |   1 +
> >  2 files changed, 34 insertions(+), 86 deletions(-)
> >
> > diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
> > index 930ac1b..a0989a0 100644
> > --- a/kernel/debug/kdb/kdb_main.c
> > +++ b/kernel/debug/kdb/kdb_main.c
> > @@ -33,6 +33,7 @@
> >  #include <linux/kallsyms.h>
> >  #include <linux/kgdb.h>
> >  #include <linux/kdb.h>
> > +#include <linux/list.h>
> >  #include <linux/notifier.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/delay.h>
> > @@ -84,15 +85,8 @@ static unsigned int kdb_continue_catastrophic =
> >  static unsigned int kdb_continue_catastrophic;
> >  #endif
> >
> > -/* kdb_commands describes the available commands. */
> > -static kdbtab_t *kdb_commands;
> > -#define KDB_BASE_CMD_MAX 50
> > -static int kdb_max_commands = KDB_BASE_CMD_MAX;
> > -static kdbtab_t kdb_base_commands[KDB_BASE_CMD_MAX];
> > -#define for_each_kdbcmd(cmd, num)                                      \
> > -       for ((cmd) = kdb_base_commands, (num) = 0;                      \
> > -            num < kdb_max_commands;                                    \
> > -            num++, num == KDB_BASE_CMD_MAX ? cmd = kdb_commands : cmd++)
> > +/* kdb_cmds_head describes the available commands. */
> > +static LIST_HEAD(kdb_cmds_head);
> >
> >  typedef struct _kdbmsg {
> >         int     km_diag;        /* kdb diagnostic */
> > @@ -921,7 +915,7 @@ int kdb_parse(const char *cmdstr)
> >         char *cp;
> >         char *cpp, quoted;
> >         kdbtab_t *tp;
> > -       int i, escaped, ignore_errors = 0, check_grep = 0;
> > +       int escaped, ignore_errors = 0, check_grep = 0;
> >
> >         /*
> >          * First tokenize the command string.
> > @@ -1011,25 +1005,18 @@ int kdb_parse(const char *cmdstr)
> >                 ++argv[0];
> >         }
> >
> > -       for_each_kdbcmd(tp, i) {
> > -               if (tp->cmd_name) {
> > -                       /*
> > -                        * If this command is allowed to be abbreviated,
> > -                        * check to see if this is it.
> > -                        */
> > -
> > -                       if (tp->cmd_minlen
> > -                        && (strlen(argv[0]) <= tp->cmd_minlen)) {
> > -                               if (strncmp(argv[0],
> > -                                           tp->cmd_name,
> > -                                           tp->cmd_minlen) == 0) {
> > -                                       break;
> > -                               }
> > -                       }
> > -
> > -                       if (strcmp(argv[0], tp->cmd_name) == 0)
> > +       list_for_each_entry(tp, &kdb_cmds_head, list_node) {
> > +               /*
> > +                * If this command is allowed to be abbreviated,
> > +                * check to see if this is it.
> > +                */
> > +               if (tp->cmd_minlen && (strlen(argv[0]) <= tp->cmd_minlen)) {
> > +                       if (strncmp(argv[0], tp->cmd_name, tp->cmd_minlen) == 0)
> >                                 break;
> >                 }
>
> The old code had the same problem, but since you're touching it you could fix?
>
> if (a) {
>   if (b)
>     break;
> }
>
> ...is the same as:
>
> if (a && b)
>   break;
>

Sure, I will fix it in the next version.

> In any case, this looks like quite a nice cleanup, so:
>
> Reviewed-by: Douglas Anderson <dianders@...omium.org>

Thanks,
Sumit