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Re: staging: ks7010: Delete unnecessary uses of the variable "retval"

From SF Markus Elfring <elfring@users.sourceforge.net>
Newsgroups linux.kernel
Subject Re: staging: ks7010: Delete unnecessary uses of the variable "retval"
Date 2016-07-21 14:50 +0200
Message-ID <rXlAn-7uo-51@gated-at.bofh.it> (permalink)
References (7 earlier) <rVZse-4jy-21@gated-at.bofh.it> <rX24F-3jb-9@gated-at.bofh.it> <rX4Jb-52e-1@gated-at.bofh.it> <rXfEB-3Gt-11@gated-at.bofh.it> <rXgAF-4nr-3@gated-at.bofh.it>
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> I think the original code was fine.

I suggest to reconsider involved implementation details once more.


> x = blah(); if (x) ... is a perfectly familiar kernel coding pattern.

I can agree to such a general information.


> There is no benefit in terms of performance

It might be possible that a good compiler can also optimise
some unnecessary variable accesses away.

Examples for further background information:
* "Minimize local variables"
   https://eventhelix.com/realtimemantra/basics/optimizingcandcppcode.htm#Minimize%20Local%20Variables

* "Temporary Objects" by Danny Kalev
   http://www.informit.com/guides/content.aspx?g=cplusplus&seqNum=198


> or understandability in dropping the variable.

I guess that we have got different opinions on such an aspect.

* Do you really want to assign every return value from a function call
  to an extra variable before it is used again?

* How many reading and understanding capacity do you need for each
  extra variable?

Regards,
Markus

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[PATCH 0/9] staging: ks7010: Fine-tuning for a SDIO card driver SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-17 20:10 +0200
  [PATCH 2/9] staging: ks7010: Delete unnecessary assignments for  buffer variables SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-17 20:20 +0200
    Re: [PATCH 2/9] staging: ks7010: Delete unnecessary assignments for  buffer variables Wolfram Sang <wsa@the-dreams.de> - 2016-07-20 17:50 +0200
  [PATCH 1/9] staging: ks7010: Delete unnecessary checks before the  function call "kfree" SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-17 20:20 +0200
    Re: [PATCH 1/9] staging: ks7010: Delete unnecessary checks before  the function call "kfree" Wolfram Sang <wsa@the-dreams.de> - 2016-07-20 17:50 +0200
  [PATCH 3/9] staging: ks7010: Return directly after a failed kmalloc() SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-17 20:20 +0200
    Re: [PATCH 3/9] staging: ks7010: Return directly after a failed  kmalloc() Julia Lawall <julia.lawall@lip6.fr> - 2016-07-17 21:00 +0200
      Re: [PATCH 3/9] staging: ks7010: Return directly after a failed  kmalloc() Wolfram Sang <wsa@the-dreams.de> - 2016-07-20 17:50 +0200
        Re: [PATCH 3/9] staging: ks7010: Return directly after a failed  kmalloc() SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-20 20:50 +0200
          Re: [PATCH 3/9] staging: ks7010: Return directly after a failed  kmalloc() Wolfram Sang <wsa@the-dreams.de> - 2016-07-21 08:30 +0200
            Re: staging: ks7010: Return directly after a failed kmalloc() SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-22 09:40 +0200
              Re: staging: ks7010: Return directly after a failed kmalloc() Wolfram Sang <wsa@the-dreams.de> - 2016-07-22 09:50 +0200
  [PATCH 7/9] staging: ks7010: Replace three printk() calls by pr_err() SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-17 20:30 +0200
    Re: [PATCH 7/9] staging: ks7010: Replace three printk() calls by  pr_err() Joe Perches <joe@perches.com> - 2016-07-17 22:30 +0200
      Re: [PATCH 7/9] staging: ks7010: Replace three printk() calls by  pr_err() Wolfram Sang <wsa@the-dreams.de> - 2016-07-20 18:00 +0200
  [PATCH 5/9] staging: ks7010: Delete unnecessary uses of the variable  "retval" SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-17 20:30 +0200
    Re: [PATCH 5/9] staging: ks7010: Delete unnecessary uses of the  variable "retval" Julia Lawall <julia.lawall@lip6.fr> - 2016-07-17 21:00 +0200
      Re: [PATCH 5/9] staging: ks7010: Delete unnecessary uses of the  variable "retval" Wolfram Sang <wsa@the-dreams.de> - 2016-07-20 18:00 +0200
        Re: [PATCH 5/9] staging: ks7010: Delete unnecessary uses of the  variable "retval" SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-20 20:50 +0200
          Re: [PATCH 5/9] staging: ks7010: Delete unnecessary uses of the  variable "retval" Wolfram Sang <wsa@the-dreams.de> - 2016-07-21 08:30 +0200
            Re: [PATCH 5/9] staging: ks7010: Delete unnecessary uses of the  variable "retval" Wolfram Sang <wsa@the-dreams.de> - 2016-07-21 09:30 +0200
            Re: [PATCH 5/9] staging: ks7010: Delete unnecessary uses of the  variable "retval" Julia Lawall <julia.lawall@lip6.fr> - 2016-07-21 09:30 +0200
              Re: staging: ks7010: Delete unnecessary uses of the variable "retval" SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-21 14:50 +0200
                Re: staging: ks7010: Delete unnecessary uses of the variable  "retval" Julia Lawall <julia.lawall@lip6.fr> - 2016-07-21 15:00 +0200
                Re: staging: ks7010: Delete unnecessary uses of the variable "retval" Wolfram Sang <wsa@the-dreams.de> - 2016-07-21 18:40 +0200
            Re: staging: ks7010: Delete unnecessary uses of the variable "retval" SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-21 15:40 +0200
              Re: staging: ks7010: Delete unnecessary uses of the variable "retval" Wolfram Sang <wsa@the-dreams.de> - 2016-07-21 18:40 +0200
                Re: staging: ks7010: Delete unnecessary uses of the variable "retval" SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-21 23:30 +0200
                Re: staging: ks7010: Delete unnecessary uses of the variable "retval" Wolfram Sang <wsa@the-dreams.de> - 2016-07-22 08:00 +0200
  [PATCH 8/9] staging: ks7010: Delete a variable in write_to_device() SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-17 20:30 +0200
    Re: [PATCH 8/9] staging: ks7010: Delete a variable in  write_to_device() Wolfram Sang <wsa@the-dreams.de> - 2016-07-20 18:00 +0200
  [PATCH 4/9] staging: ks7010: Rename jump labels SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-17 20:30 +0200
    Re: [PATCH 4/9] staging: ks7010: Rename jump labels Wolfram Sang <wsa@the-dreams.de> - 2016-07-20 18:00 +0200
      Re: staging: ks7010: Rename jump labels SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-20 20:30 +0200
        Re: staging: ks7010: Rename jump labels Jean Delvare <jdelvare@suse.de> - 2016-07-20 23:20 +0200
          Re: staging: ks7010: Rename jump labels Wolfram Sang <wsa@the-dreams.de> - 2016-07-21 08:30 +0200
          Re: staging: ks7010: Rename jump labels "SF Markus Elfring" <elfring@users.sourceforge.net> - 2016-07-21 10:00 +0200
            Re: staging: ks7010: Rename jump labels Jean Delvare <jdelvare@suse.de> - 2016-07-25 14:40 +0200
          Re: staging: ks7010: Rename jump labels SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-21 17:40 +0200
            Re: staging: ks7010: Rename jump labels Jean Delvare <jdelvare@suse.de> - 2016-07-21 21:20 +0200
              Re: staging: ks7010: Rename jump labels SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-21 22:30 +0200
                Re: staging: ks7010: Rename jump labels Jean Delvare <jdelvare@suse.de> - 2016-07-25 14:40 +0200
                Re: staging: ks7010: Rename jump labels SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-25 18:20 +0200
                Re: staging: ks7010: Rename jump labels Jean Delvare <jdelvare@suse.de> - 2016-07-25 23:10 +0200
  [PATCH 6/9] staging: ks7010: Delete unnecessary braces SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-17 20:30 +0200
    Re: [PATCH 6/9] staging: ks7010: Delete unnecessary braces Julia Lawall <julia.lawall@lip6.fr> - 2016-07-17 21:00 +0200
      Re: [PATCH 6/9] staging: ks7010: Delete unnecessary braces Wolfram Sang <wsa@the-dreams.de> - 2016-07-20 18:00 +0200
  [PATCH 9/9] staging: ks7010: Delete three unnecessary variable  initialisations SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-17 20:40 +0200
    Re: [PATCH 9/9] staging: ks7010: Delete three unnecessary variable  initialisations Julia Lawall <julia.lawall@lip6.fr> - 2016-07-17 21:00 +0200
      Re: [PATCH 9/9] staging: ks7010: Delete three unnecessary variable  initialisations Wolfram Sang <wsa@the-dreams.de> - 2016-07-20 18:00 +0200
      Re: [PATCH 9/9] staging: ks7010: Delete three unnecessary variable  initialisations SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-21 15:50 +0200
        Re: [PATCH 9/9] staging: ks7010: Delete three unnecessary variable  initialisations Julia Lawall <julia.lawall@lip6.fr> - 2016-07-21 16:00 +0200
          Re: staging: ks7010: Delete three unnecessary variable  initialisations SF Markus Elfring <elfring@users.sourceforge.net> - 2016-07-21 16:20 +0200

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