How to find linux kernel bugs based on changelog

Asked by Vinh Nguyen on 2016-03-03

Hi all,
I have a problem about "find linux kernel bugs based on changelog". In the changelog file, i saw many "fix error" but i can't find bugs related with that error. For example, i checkout to linux-3.4.y from linux kernel stable and git log linux kernel 3.4.x version and focus in hwmon-vid driver with syntax as: git log --follow drivers/hwmon/hwmon-vid.c.
I get commit as below:
  commit f352df652ff37c434ed32bc5b7eb7ce430b73abc
  Author: Guenter Roeck <email address hidden>
  Date: Tue Jan 24 17:55:00 2012 -0800
     hwmon: (hwmon-vid) Fix checkpatch issues

      ERROR: code indent should use tabs where possible
      ERROR: space required before the open parenthesis '('
      WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable

      Not fixed (url):
      WARNING: line over 80 characters

      Not fixed (false positive):
      ERROR: Macros with complex values should be enclosed in parenthesis

      Cc: Rudolf Marek <email address hidden>
      Signed-off-by: Guenter Roeck <email address hidden>
      Acked-by: Jean Delvare <email address hidden>
i can't find error or bugs related it. Can you guys teach me how to find linux kernel bugs based on changelog.
thanks & best regard

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Could email the email addresses you pasted and see if they know....

Vinh Nguyen (vinh-nguyen) said : #2

hi andrew,
i have been email to guenter roeck,
if you guys know how to find bugs, please help me.
best and regard

As the subject suggests, the commit in question addresses checkpatch issues, or in other words coding style problems.

The keyword "ERROR" or "WARNING" does not necessarily mean that there was a bug in the code. It all depends on the context.

Recent patches are supposed to have a "Fixes:" tag if they fix a problem with a previous commit. One can reasonably assume that a patch marked with "FIxes:" is a bug fix. However, there are many bug fixes which are not marked that way, so checking for Fixes: alone will only yield a very incomplete list. Reading the change log is the only way to really find out. While not perfect either, most of the time it describes pretty well what is changed and why.

Vinh Nguyen (vinh-nguyen) said : #4

Hi Guenter Roeck,
thanks for repplied. i understood your explain. I want to find all of importance bugs fix relate some drivers as e1000e, hwmon-vid, i2c-i801. But have many bugs not relate,.
Can you teach me the method how to find bugs linux kernel relate drivers abow and how to pull (download/git ) all of bugs when i found to my computer.
thanks and best regard

Vinh Nguyen (vinh-nguyen) said : #5

as commit below
'commit c81ac5970095a62139f4904e638c304b220e76e5
Author: Guenter Roeck <email address hidden>
Date: Fri Jan 21 09:42:17 2011 +0100

hwmon: (w83627ehf) Fix max_output and step_output readings

    [extraction from commit da2e025590cf7038440132d4bbc967a579b11112 upstream]

    The value of max_output and step_output registers isn't read from the
    respective registers. As a result, zero values are returned to the
    user through the respective sysfs attributes, instead of the actual
    fan control settings.

    The problem is fixed by updating the fan max output and fan step
    output information from data in registers.

    Signed-off-by: Guenter Roeck <email address hidden>
    Signed-off-by: Jean Delvare <email address hidden>
    Signed-off-by: Paul Gortmaker <email address hidden>

i only know that you Fix max_output and step_output readings (i have beed read souce code that you changed)
but i don't know you fix problem that for bug or no? and if that is bug, how can i find this bug
thank and best regard

Vinh Nguyen (vinh-nguyen) said : #6

and if some commit don't have "fix" tag but this fix for e1000e driver
as bug id
this relate bug fix for e1000e driver, but when i find with keywork "e1000e" or "save skb counts in TX to avoid cache misses" i don't get bugs as link below.

It seems that you expect or assume that there would be a formal bug entry in a bug database (eg here or at for each patch or bug fix in the Linux kernel. This is not the case.

The "Fixes" tag identifies a different commit which is fixed with a given patch, not a bug entry in a bug database.

Bug fixed in, say, e1000e, hwmon-vid, i2c-i801, or any other driver or subsystem, can be identified quite easily by examining the commit log of those drivers or subsystems.

Can you maybe explain what problem you are actually trying to solve ?

Vinh Nguyen (vinh-nguyen) said : #8

Dear Guenter Roeck!
thanks for explain,i understood that;
that resolve my problem.

in addition, can you teach me the method to find all of bugs relate one modul or driver?

Can you help with this problem?

Provide an answer of your own, or ask Vinh Nguyen for more information if necessary.

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