Re: [PATCH v2] Avoid address_space_rw() with a constant is_write argument

[Philippe Mathieu-Daudé]

On 2/18/20 1:56 PM, Philippe Mathieu-Daudé wrote:
> On 2/18/20 12:24 PM, Peter Maydell wrote:
> > The address_space_rw() function allows either reads or writes
> > depending on the is_write argument passed to it; this is useful
> > when the direction of the access is determined programmatically
> > (as for instance when handling the KVM_EXIT_MMIO exit reason).
> > Under the hood it just calls either address_space_write() or
> > address_space_read_full().
> >
> > We also use it a lot with a constant is_write argument, though,
> > which has two issues:
> >   * when reading "address_space_rw(..., 1)" this is less
> >     immediately clear to the reader as being a write than
> >     "address_space_write(...)"
> >   * calling address_space_rw() bypasses the optimization
> >     in address_space_read() that fast-paths reads of a
> >     fixed length
> >
> > This commit was produced with the included Coccinelle script
> > scripts/coccinelle/as-rw-const.patch.

Script is "scripts/coccinelle/as_rw_const.cocci".

I plan to respin this patch (fixed) in a larger series.

> > Two lines in hw/net/dp8393x.c that Coccinelle produced that
> > were over 80 characters were re-wrapped by hand.
> >
> > Signed-off-by: Peter Maydell <address@hidden>
> > ---
> > I could break this down into separate patches by submaintainer,
> > but the patch is not that large and I would argue that it's
> > better for the project if we can try to avoid introducing too
> > much friction into the process of doing 'safe' tree-wide
> > minor refactorings.
> >
> > v1->v2: put the coccinelle script in scripts/coccinelle rather
> > than just in the commit message.
> > ---
> >   accel/kvm/kvm-all.c                  |  6 +--
> >   dma-helpers.c                        |  4 +-
> >   exec.c                               |  4 +-
> >   hw/dma/xlnx-zdma.c                   | 11 ++---
> >   hw/net/dp8393x.c                     | 68 ++++++++++++++--------------
> >   hw/net/i82596.c                      | 25 +++++-----
> >   hw/net/lasi_i82596.c                 |  5 +-
> >   hw/ppc/pnv_lpc.c                     |  8 ++--
> >   hw/s390x/css.c                       | 12 ++---
> >   qtest.c                              | 52 ++++++++++-----------
> >   target/i386/hvf/x86_mmu.c            | 12 ++---
> >   scripts/coccinelle/as_rw_const.cocci | 30 ++++++++++++
> >   12 files changed, 133 insertions(+), 104 deletions(-)
> >   create mode 100644 scripts/coccinelle/as_rw_const.cocci