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author | Daniel Thompson <daniel.thompson@linaro.org> | 2019-10-25 09:33:25 +0200 |
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committer | Daniel Thompson <daniel.thompson@linaro.org> | 2019-10-28 13:02:21 +0100 |
commit | d04213af90935d8b247c1327c9ea142fc037165f (patch) | |
tree | acb625f166ec6fdffb70bda937c4bf9fc8305c85 /kernel/debug/kdb/kdb_private.h | |
parent | kdb: Tidy up code to handle escape sequences (diff) | |
download | linux-d04213af90935d8b247c1327c9ea142fc037165f.tar.xz linux-d04213af90935d8b247c1327c9ea142fc037165f.zip |
kdb: Simplify code to fetch characters from console
Currently kdb_read_get_key() contains complex control flow that, on
close inspection, turns out to be unnecessary. In particular:
1. It is impossible to enter the branch conditioned on (escape_delay == 1)
except when the loop enters with (escape_delay == 2) allowing us to
combine the branches.
2. Most of the code conditioned on (escape_delay == 2) simply modifies
local data and then breaks out of the loop causing the function to
return escape_data[0].
3. Based on #2 there is not actually any need to ever explicitly set
escape_delay to 2 because we it is much simpler to directly return
escape_data[0] instead.
4. escape_data[0] is, for all but one exit path, known to be '\e'.
Simplify the code based on these observations.
There is a subtle (and harmless) change of behaviour resulting from this
simplification: instead of letting the escape timeout after ~1998
milliseconds we now timeout after ~2000 milliseconds
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20191025073328.643-3-daniel.thompson@linaro.org
Diffstat (limited to 'kernel/debug/kdb/kdb_private.h')
0 files changed, 0 insertions, 0 deletions