Messages in this thread | | | From | Sumit Garg <> | Date | Fri, 8 May 2020 17:32:24 +0530 | Subject | Re: [PATCH] kdb: Cleanup math with KDB_CMD_HISTORY_COUNT |
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On Fri, 8 May 2020 at 04:42, Douglas Anderson <dianders@chromium.org> wrote: > > From code inspection the math in handle_ctrl_cmd() looks super sketchy > because it subjects -1 from cmdptr and then does a "% > KDB_CMD_HISTORY_COUNT". It turns out that this code works because > "cmdptr" is unsigned and KDB_CMD_HISTORY_COUNT is a nice power of 2. > Let's make this a little less sketchy. > > This patch should be a no-op. > > Signed-off-by: Douglas Anderson <dianders@chromium.org> > --- >
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
> kernel/debug/kdb/kdb_main.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c > index 515379cbf209..6865a0f58d38 100644 > --- a/kernel/debug/kdb/kdb_main.c > +++ b/kernel/debug/kdb/kdb_main.c > @@ -1108,7 +1108,8 @@ static int handle_ctrl_cmd(char *cmd) > switch (*cmd) { > case CTRL_P: > if (cmdptr != cmd_tail) > - cmdptr = (cmdptr-1) % KDB_CMD_HISTORY_COUNT; > + cmdptr = (cmdptr + KDB_CMD_HISTORY_COUNT - 1) % > + KDB_CMD_HISTORY_COUNT; > strscpy(cmd_cur, cmd_hist[cmdptr], CMD_BUFLEN); > return 1; > case CTRL_N: > -- > 2.26.2.645.ge9eca65c58-goog >
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