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| author | Douglas Anderson <dianders@chromium.org> | 2020-05-07 16:11:46 -0700 |
|---|---|---|
| committer | Daniel Thompson <daniel.thompson@linaro.org> | 2020-06-02 15:15:46 +0100 |
| commit | 1b310030bb855b9b13d1c0a9feffdb54883b06ab (patch) | |
| tree | 83c8710aa1c85c2cbb79ac3dfea06fe1a09fc2bc /kernel/debug | |
| parent | 195867ffea13b755dc727b47eaa5beb0ffa6e0ce (diff) | |
| download | linux-1b310030bb855b9b13d1c0a9feffdb54883b06ab.tar.bz2 | |
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')
| -rw-r--r-- | kernel/debug/kdb/kdb_main.c | 3 |
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) % + KDB_CMD_HISTORY_COUNT; strscpy(cmd_cur, cmd_hist[cmdptr], CMD_BUFLEN); return 1; case CTRL_N: |