Commit 1b310030 authored May 07, 2020 by Douglas Anderson Committed by Daniel Thompson Jun 02, 2020

kdb: Cleanup math with KDB_CMD_HISTORY_COUNT



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>
Link: https://lore.kernel.org/r/20200507161125.1.I2cce9ac66e141230c3644b8174b6c15d4e769232@changeid


Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>

parent 195867ff

kernel/debug/kdb/kdb_main.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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:

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