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SubjectRE: [PATCH 2/2] vmbus: make hv_get_ringbuffer_availbytes local
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> -----Original Message-----
> From: Greg KH [mailto:gregkh@linuxfoundation.org]
> Sent: Tuesday, November 28, 2017 7:35 AM
> To: KY Srinivasan <kys@microsoft.com>
> Cc: linux-kernel@vger.kernel.org; devel@linuxdriverproject.org;
> olaf@aepfle.de; apw@canonical.com; vkuznets@redhat.com;
> jasowang@redhat.com; leann.ogasawara@canonical.com;
> marcelo.cerri@canonical.com; Stephen Hemminger
> <sthemmin@microsoft.com>; Stephen Hemminger
> <stephen@networkplumber.org>
> Subject: Re: [PATCH 2/2] vmbus: make hv_get_ringbuffer_availbytes local
>
> On Tue, Nov 14, 2017 at 10:52:08AM -0700, kys@exchange.microsoft.com
> wrote:
> > From: Stephen Hemminger <stephen@networkplumber.org>
> >
> > hv_get_ringbuffer_availbytes is only used by the debug info
> > routine so make it static. Also, add READ_ONCE() to avoid any
> > possible issues with potentially volatile index values.
> >
> > Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
> > Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
> > ---
> > drivers/hv/ring_buffer.c | 23 +++++++++++++++++++++++
> > include/linux/hyperv.h | 22 ----------------------
> > 2 files changed, 23 insertions(+), 22 deletions(-)
> >
> > diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
> > index 12eb8ca..50e0714 100644
> > --- a/drivers/hv/ring_buffer.c
> > +++ b/drivers/hv/ring_buffer.c
> > @@ -140,6 +140,29 @@ static u32 hv_copyto_ringbuffer(
> > return start_write_offset;
> > }
> >
> > +/*
> > + *
> > + * hv_get_ringbuffer_availbytes()
> > + *
> > + * Get number of bytes available to read and to write to
> > + * for the specified ring buffer
> > + */
> > +static void
> > +hv_get_ringbuffer_availbytes(const struct hv_ring_buffer_info *rbi,
> > + u32 *read, u32 *write)
> > +{
> > + u32 read_loc, write_loc, dsize;
> > +
> > + /* Capture the read/write indices before they changed */
> > + read_loc = READ_ONCE(rbi->ring_buffer->read_index);
> > + write_loc = READ_ONCE(rbi->ring_buffer->write_index);
> > + dsize = rbi->ring_datasize;
> > +
> > + *write = write_loc >= read_loc ? dsize - (write_loc - read_loc) :
> > + read_loc - write_loc;
> > + *read = dsize - *write;
> > +}
> > +
> > /* Get various debug metrics for the specified ring buffer. */
> > void hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info
> *ring_info,
> > struct hv_ring_buffer_debug_info
> *debug_info)
> > diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> > index 6c93366..93bd6fc 100644
> > --- a/include/linux/hyperv.h
> > +++ b/include/linux/hyperv.h
> > @@ -127,28 +127,6 @@ struct hv_ring_buffer_info {
> > u32 priv_read_index;
> > };
> >
> > -/*
> > - *
> > - * hv_get_ringbuffer_availbytes()
> > - *
> > - * Get number of bytes available to read and to write to
> > - * for the specified ring buffer
> > - */
> > -static inline void
> > -hv_get_ringbuffer_availbytes(const struct hv_ring_buffer_info *rbi,
> > - u32 *read, u32 *write)
> > -{
> > - u32 read_loc, write_loc, dsize;
> > -
> > - /* Capture the read/write indices before they changed */
> > - read_loc = rbi->ring_buffer->read_index;
> > - write_loc = rbi->ring_buffer->write_index;
> > - dsize = rbi->ring_datasize;
> > -
> > - *write = write_loc >= read_loc ? dsize - (write_loc - read_loc) :
> > - read_loc - write_loc;
> > - *read = dsize - *write;
> > -}
> >
> > static inline u32 hv_get_bytes_to_read(const struct hv_ring_buffer_info
> *rbi)
> > {
> > --
> > 1.7.1
>
> This breaks the build.
>
> Please be more careful...

Sorry about that. I did not have a build issue on the tree I tested. I will rebase and send.

K. Y
>
> greg k-h

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