path: root/kernel/debug/kdb
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authorDouglas Anderson <dianders@chromium.org>2020-05-07 16:11:46 -0700
committerDaniel Thompson <daniel.thompson@linaro.org>2020-06-02 15:15:46 +0100
commit1b310030bb855b9b13d1c0a9feffdb54883b06ab (patch)
tree83c8710aa1c85c2cbb79ac3dfea06fe1a09fc2bc /kernel/debug/kdb
parent195867ffea13b755dc727b47eaa5beb0ffa6e0ce (diff)
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>
Diffstat (limited to 'kernel/debug/kdb')
1 files changed, 2 insertions, 1 deletions
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) %
strscpy(cmd_cur, cmd_hist[cmdptr], CMD_BUFLEN);
return 1;
case CTRL_N:

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