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author | Alex Elder <elder@linaro.org> | 2014-07-16 08:44:38 -0500 |
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committer | Alex Elder <elder@linaro.org> | 2014-07-17 08:54:53 -0500 |
commit | cf1b51674ddc5f9b714df84ebaa018dfc8d6b758 (patch) | |
tree | 5347f2db6e294c8781b0879a8c07f2f7c9fb6ebd /drivers/devfreq/governor_userspace.c | |
parent | 910bdfdd0078d5c4114a85954300623da8f068a7 (diff) |
printk: honor LOG_PREFIX in devkmsg_read()
In devkmsg_read(), a variable "cont" holds a character that's used
to indicate whether a given log line is a "continuation", that is,
whether a log record should be merged with the one before or after
it. If a record should be merged with its successor (but not its
predecessor) that character is 'c'. And the line following such a
'c' log record is normally marked with a '+' to show it is continues
its predecessor. Any other cases are marked '-', indicating the
log record stands on its own.
There is an exception. If a log record is marked LOG_PREFIX, it
indicates that this record represents a new log entry, implicitly
terminating the predecessor--even if the predecessor would otherwise
have been continued. So a record marked LOG_PREFIX (that is not
also marked LOG_CONT) should have '-' for its "cont" variable.
The logic that determines this "continuation" character has a bug
that gets that exceptional case wrong.
The specific case that produces the wrong result is when all of
these conditions are non-zero:
user->prev & LOG_CONT
msg->flags & LOG_PREFIX
msg->flags & LOG_CONT
The bug is that despite the message's LOG_PREFIX flag, the
"cont" character is getting set to '+' rather than 'c'.
The problem is that the message's LOG_PREFIX flag is getting
ignored if its LOG_CONT flag is also set. Rearrange the logic
here to produce the correct result.
The following table concisely defines the problem:
prev | msg | msg ||"cont"
CONT |PREFIX| CONT || char
------+------+------++------
clear| clear| clear|| '-'
clear| clear| set || 'c'
clear| set | clear|| '-'
clear| set | set || 'c'
set | clear| clear|| '+'
set | clear| set || '+'
set | set | clear|| '-'
set | set | set || '+' <-- should be 'c'
Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Diffstat (limited to 'drivers/devfreq/governor_userspace.c')
0 files changed, 0 insertions, 0 deletions