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[v3,0/7] include: add setbits32/clrbits32/clrsetbits32/setbits64/clrbits64/clrsetbits64

Message ID 1540366553-18541-1-git-send-email-clabbe@baylibre.com (mailing list archive)
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Series include: add setbits32/clrbits32/clrsetbits32/setbits64/clrbits64/clrsetbits64 | expand

Message

Corentin LABBE Oct. 24, 2018, 7:35 a.m. UTC
Hello

This patchset adds a new set of functions which are open-coded in lot of
place.
Basicly the pattern is always the same, "read, modify a bit, write"
some driver and the powerpc arch already have thoses pattern them as functions. (like ahci_sunxi.c or dwmac-meson8b)

The first patch rename some powerpc functions for being consistent with
the new name convention.

The second patch adds the header with all setbits functions.

The third patch is a try to implement a coccinelle semantic patch to
find all place where xxxbits function could be used.
It should not be merged since it is un-finalized.
For the moment, the "add setbits.h header" is not working and need a future
coccinelle version.

The four last patch are example of some drivers conversion.
Thoses patchs give an example of the reduction of code won by using xxxbits32.

I would like to thanks Julia Lawall for her help on the coccinelle
patch.

Note that I dont know which maintainer will take the linux/setbits.h include patch.

Regards

Changes since v2:
- Fixed patch title
- Fixed style problems
- shorted macro arguments name

Changes since v1:
- renamed LE functions to _leXX
- updated coccinnelle patch with JLawall's comments

Corentin Labbe (7):
  powerpc: rename setbits32/clrbits32 to setbits_be32/clrbits_be32
  include: add setbits_leXX/clrbits_leXX/clrsetbits_leXX in
    linux/setbits.h
  coccinelle: add xxxsetbits_leXX converting spatch
  ata: ahci_sunxi: use xxxsetbitsi_le32 functions
  net: ethernet: stmmac: dwmac-sun8i: use xxxsetbits_le32
  drm: meson: use xxxsetbits_le32
  net: stmmac: dwmac-meson8b: use xxxsetbits_le32

 arch/powerpc/include/asm/fsl_lbc.h            |   2 +-
 arch/powerpc/include/asm/io.h                 |   4 +-
 arch/powerpc/platforms/44x/canyonlands.c      |   4 +-
 arch/powerpc/platforms/4xx/gpio.c             |  28 +-
 arch/powerpc/platforms/512x/pdm360ng.c        |   6 +-
 arch/powerpc/platforms/52xx/mpc52xx_common.c  |   6 +-
 arch/powerpc/platforms/52xx/mpc52xx_gpt.c     |  12 +-
 arch/powerpc/platforms/82xx/ep8248e.c         |   2 +-
 arch/powerpc/platforms/82xx/km82xx.c          |   6 +-
 arch/powerpc/platforms/82xx/mpc8272_ads.c     |  10 +-
 arch/powerpc/platforms/82xx/pq2.c             |   2 +-
 arch/powerpc/platforms/82xx/pq2ads-pci-pic.c  |   4 +-
 arch/powerpc/platforms/82xx/pq2fads.c         |  10 +-
 arch/powerpc/platforms/83xx/km83xx.c          |   6 +-
 arch/powerpc/platforms/83xx/mpc836x_mds.c     |   2 +-
 arch/powerpc/platforms/85xx/mpc85xx_mds.c     |   2 +-
 arch/powerpc/platforms/85xx/mpc85xx_pm_ops.c  |   4 +-
 arch/powerpc/platforms/85xx/mpc85xx_rdb.c     |   2 +-
 arch/powerpc/platforms/85xx/p1022_ds.c        |   6 +-
 arch/powerpc/platforms/85xx/p1022_rdk.c       |   6 +-
 arch/powerpc/platforms/85xx/t1042rdb_diu.c    |   6 +-
 arch/powerpc/platforms/85xx/twr_p102x.c       |   2 +-
 arch/powerpc/platforms/86xx/mpc8610_hpcd.c    |   6 +-
 arch/powerpc/platforms/8xx/adder875.c         |   2 +-
 arch/powerpc/platforms/8xx/m8xx_setup.c       |   4 +-
 arch/powerpc/platforms/8xx/mpc86xads_setup.c  |   4 +-
 arch/powerpc/platforms/8xx/mpc885ads_setup.c  |  28 +-
 .../platforms/embedded6xx/flipper-pic.c       |   6 +-
 arch/powerpc/platforms/embedded6xx/hlwd-pic.c |   8 +-
 arch/powerpc/platforms/embedded6xx/wii.c      |  12 +-
 arch/powerpc/sysdev/cpm1.c                    |  26 +-
 arch/powerpc/sysdev/cpm2.c                    |  16 +-
 arch/powerpc/sysdev/cpm_common.c              |   4 +-
 arch/powerpc/sysdev/fsl_85xx_l2ctlr.c         |  16 +-
 arch/powerpc/sysdev/fsl_lbc.c                 |   2 +-
 arch/powerpc/sysdev/fsl_pci.c                 |  12 +-
 arch/powerpc/sysdev/fsl_pmc.c                 |   2 +-
 arch/powerpc/sysdev/fsl_rcpm.c                |  74 +--
 arch/powerpc/sysdev/fsl_rio.c                 |   4 +-
 arch/powerpc/sysdev/fsl_rmu.c                 |   9 +-
 arch/powerpc/sysdev/mpic_timer.c              |  12 +-
 drivers/ata/ahci_sunxi.c                      |  62 +--
 drivers/gpu/drm/meson/meson_crtc.c            |  14 +-
 drivers/gpu/drm/meson/meson_dw_hdmi.c         |  33 +-
 drivers/gpu/drm/meson/meson_plane.c           |  13 +-
 drivers/gpu/drm/meson/meson_registers.h       |   3 -
 drivers/gpu/drm/meson/meson_venc.c            |  13 +-
 drivers/gpu/drm/meson/meson_venc_cvbs.c       |   4 +-
 drivers/gpu/drm/meson/meson_viu.c             |  65 +--
 drivers/gpu/drm/meson/meson_vpp.c             |  22 +-
 .../ethernet/stmicro/stmmac/dwmac-meson8b.c   |  56 +-
 .../net/ethernet/stmicro/stmmac/dwmac-sun8i.c |  62 +--
 include/linux/setbits.h                       |  84 +++
 scripts/add_new_include_in_source.py          |  61 +++
 scripts/coccinelle/misc/setbits32.cocci       | 487 ++++++++++++++++++
 .../coccinelle/misc/setbits32_relaxed.cocci   | 487 ++++++++++++++++++
 scripts/coccinelle/misc/setbits64.cocci       | 487 ++++++++++++++++++
 scripts/coccinelle/misc/setbits_dev.cocci     | 235 +++++++++
 58 files changed, 2172 insertions(+), 395 deletions(-)
 create mode 100644 include/linux/setbits.h
 create mode 100755 scripts/add_new_include_in_source.py
 create mode 100644 scripts/coccinelle/misc/setbits32.cocci
 create mode 100644 scripts/coccinelle/misc/setbits32_relaxed.cocci
 create mode 100644 scripts/coccinelle/misc/setbits64.cocci
 create mode 100644 scripts/coccinelle/misc/setbits_dev.cocci

Comments

Russell King (Oracle) Oct. 24, 2018, 8:57 a.m. UTC | #1
On Wed, Oct 24, 2018 at 07:35:46AM +0000, Corentin Labbe wrote:
> This patchset adds a new set of functions which are open-coded in lot of
> place.
> Basicly the pattern is always the same, "read, modify a bit, write"
> some driver and the powerpc arch already have thoses pattern them as functions. (like ahci_sunxi.c or dwmac-meson8b)

The advantage of them being open-coded is that it's _obvious_ to the
reviewer that there is a read-modify-write going on which, in a multi-
threaded environment, may need some locking (so it should trigger a
review of the locking around that code.)

With it hidden inside a helper which has no locking itself, it becomes
much easier to pass over in review, which means that races are much
more likely to go unspotted - and that is bad news.
Corentin LABBE Nov. 15, 2018, 9:30 a.m. UTC | #2
On Wed, Oct 24, 2018 at 09:57:00AM +0100, Russell King - ARM Linux wrote:
> On Wed, Oct 24, 2018 at 07:35:46AM +0000, Corentin Labbe wrote:
> > This patchset adds a new set of functions which are open-coded in lot of
> > place.
> > Basicly the pattern is always the same, "read, modify a bit, write"
> > some driver and the powerpc arch already have thoses pattern them as functions. (like ahci_sunxi.c or dwmac-meson8b)
> 
> The advantage of them being open-coded is that it's _obvious_ to the
> reviewer that there is a read-modify-write going on which, in a multi-
> threaded environment, may need some locking (so it should trigger a
> review of the locking around that code.)
> 
> With it hidden inside a helper which has no locking itself, it becomes
> much easier to pass over in review, which means that races are much
> more likely to go unspotted - and that is bad news.
> 

Hello

I understand your fear, but I think the benefit overhaul thoses.
Furthermore, drivers which I have converted does not need such locking.

If you want I can rename the header to linux/setbits-non-atomic.h for making obvious the lack of locking.

Regards
Russell King (Oracle) Nov. 15, 2018, 9:33 a.m. UTC | #3
On Thu, Nov 15, 2018 at 10:30:34AM +0100, LABBE Corentin wrote:
> On Wed, Oct 24, 2018 at 09:57:00AM +0100, Russell King - ARM Linux wrote:
> > On Wed, Oct 24, 2018 at 07:35:46AM +0000, Corentin Labbe wrote:
> > > This patchset adds a new set of functions which are open-coded in lot of
> > > place.
> > > Basicly the pattern is always the same, "read, modify a bit, write"
> > > some driver and the powerpc arch already have thoses pattern them as functions. (like ahci_sunxi.c or dwmac-meson8b)
> > 
> > The advantage of them being open-coded is that it's _obvious_ to the
> > reviewer that there is a read-modify-write going on which, in a multi-
> > threaded environment, may need some locking (so it should trigger a
> > review of the locking around that code.)
> > 
> > With it hidden inside a helper which has no locking itself, it becomes
> > much easier to pass over in review, which means that races are much
> > more likely to go unspotted - and that is bad news.
> > 
> 
> Hello
> 
> I understand your fear, but I think the benefit overhaul thoses.
> Furthermore, drivers which I have converted does not need such locking.
> 
> If you want I can rename the header to linux/setbits-non-atomic.h for making obvious the lack of locking.

It'd probably be better in the function name - it then doesn't get
"lost" that it's non-atomic when it's included via other headers.
Corentin LABBE Nov. 15, 2018, 12:24 p.m. UTC | #4
On Thu, Nov 15, 2018 at 09:33:48AM +0000, Russell King - ARM Linux wrote:
> On Thu, Nov 15, 2018 at 10:30:34AM +0100, LABBE Corentin wrote:
> > On Wed, Oct 24, 2018 at 09:57:00AM +0100, Russell King - ARM Linux wrote:
> > > On Wed, Oct 24, 2018 at 07:35:46AM +0000, Corentin Labbe wrote:
> > > > This patchset adds a new set of functions which are open-coded in lot of
> > > > place.
> > > > Basicly the pattern is always the same, "read, modify a bit, write"
> > > > some driver and the powerpc arch already have thoses pattern them as functions. (like ahci_sunxi.c or dwmac-meson8b)
> > > 
> > > The advantage of them being open-coded is that it's _obvious_ to the
> > > reviewer that there is a read-modify-write going on which, in a multi-
> > > threaded environment, may need some locking (so it should trigger a
> > > review of the locking around that code.)
> > > 
> > > With it hidden inside a helper which has no locking itself, it becomes
> > > much easier to pass over in review, which means that races are much
> > > more likely to go unspotted - and that is bad news.
> > > 
> > 
> > Hello
> > 
> > I understand your fear, but I think the benefit overhaul thoses.
> > Furthermore, drivers which I have converted does not need such locking.
> > 
> > If you want I can rename the header to linux/setbits-non-atomic.h for making obvious the lack of locking.
> 
> It'd probably be better in the function name - it then doesn't get
> "lost" that it's non-atomic when it's included via other headers.
> 

I proposed that way for doing like writeq have do it with io-64-nonatomic-hi-lo.h