2016-10-31 Rob Clark <robdclark at gmail.com>:
> On Mon, Oct 31, 2016 at 9:55 AM, Chris Wilson <chris at chris-wilson.co.uk>
> wrote:
> > On Mon, Oct 31, 2016 at 09:44:07AM -0400, Rob Clark wrote:
> >> From: Rob Clark <robclark at freedesktop.org>
> >>
> >> Rather than cut/pasting these couple ioctl wrappers everywhere, just
> >> stuff them as static-inline into a header.
> >>
> >> Signed-off-by: Rob Clark <robclark at freedesktop.org>
> >> ---
> >> This is probably mostly used from mesa, but some drivers, test apps, etc
> >> may also want to use it from libdrm.
> >>
> >> Makefile.sources | 1 +
> >> libsync.h | 74
> >> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >> 2 files changed, 75 insertions(+)
> >> create mode 100644 libsync.h
> >>
> >> diff --git a/Makefile.sources b/Makefile.sources
> >> index a57036a..10aa1d0 100644
> >> --- a/Makefile.sources
> >> +++ b/Makefile.sources
> >> @@ -13,6 +13,7 @@ LIBDRM_FILES := \
> >> util_math.h
> >>
> >> LIBDRM_H_FILES := \
> >> + libsync.h \
> >> xf86drm.h \
> >> xf86drmMode.h
> >>
> >> diff --git a/libsync.h b/libsync.h
> >> new file mode 100644
> >> index 0000000..fc23b7f
> >> --- /dev/null
> >> +++ b/libsync.h
> >> @@ -0,0 +1,74 @@
> >> +/*
> >> + * sync abstraction
> >> + * Copyright 2015-2016 Collabora Ltd.
> >> + *
> >> + * Based on the implementation from the Android Open Source Project,
> >> + *
> >> + * Copyright 2012 Google, Inc
> >> + *
> >> + * Permission is hereby granted, free of charge, to any person obtaining
> >> a
> >> + * copy of this software and associated documentation files (the
> >> "Software"),
> >> + * to deal in the Software without restriction, including without
> >> limitation
> >> + * the rights to use, copy, modify, merge, publish, distribute,
> >> sublicense,
> >> + * and/or sell copies of the Software, and to permit persons to whom the
> >> + * Software is furnished to do so, subject to the following conditions:
> >> + *
> >> + * The above copyright notice and this permission notice shall be
> >> included in
> >> + * all copies or substantial portions of the Software.
> >> + *
> >> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
> >> EXPRESS OR
> >> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
> >> MERCHANTABILITY,
> >> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
> >> SHALL
> >> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
> >> + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
> >> + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
> >> + * OTHER DEALINGS IN THE SOFTWARE.
> >> + */
> >> +
> >> +#ifndef _LIBSYNC_H
> >> +#define _LIBSYNC_H
> >> +
> >> +#include <stdint.h>
> >> +#include <string.h>
> >> +#include <sys/ioctl.h>
> >> +#include <sys/poll.h>
> >> +
> >> +// todo prob should just #include <linux/sync_file.h> ?
> >> +struct sync_merge_data {
> >> + char name[32];
> >> + int32_t fd2;
> >> + int32_t fence;
> >> + uint32_t flags;
> >> + uint32_t pad;
> >> +};
> >> +#define SYNC_IOC_MAGIC '>'
> >> +#define SYNC_IOC_MERGE _IOWR(SYNC_IOC_MAGIC, 3, struct
> >> sync_merge_data)
> >> +
> >> +
> >> +
> >> +static inline int sync_wait(int fd, int timeout)
> >> +{
> >> + struct pollfd fds;
> >> +
> >> + fds.fd = fd;
> >> + fds.events = POLLIN | POLLERR;
> >
> > POLLERR is implied and ignored in fds.events.
> >
> >> + return poll(&fds, 1, timeout);
> >
> > Returns: -1 on error, 0 on timeout, 1 if signaled.
> >
> > This function is horrible wrt to -EINTR for example :) Hmm, mixing
> > poll() and looping over signals until timeout doesn't look as
> > straightforward.
>
> hmm, this was just basically cut/paste from android libsync (and iirc
> removing the legacy ioctls).. although I did just realize there was a
> newer version which turned this into:
>
> ret = poll(..);
> if (ret > 0)
> return 0;
> return ret;
>
> perhaps not super-awesome for -EINTR handling.. and tbh I'm 100% of
> the behavior when this used to be simply "return ioctl(fd,
> SYNC_IOC_WAIT, &to);"..
The latest version take a few more cases in account and should behave
exatly like SYNC_IOC_WAIT.
int sync_wait(int fd, int timeout)
{
struct pollfd fds;
int ret;
fds.fd = fd;
fds.events = POLLIN;
ret = poll(&fds, 1, timeout);
if (ret > 0) {
if (fds.revents & (POLLERR | POLLNVAL))
errno = EINVAL;
return -1;
return 0;
} else if (ret == 0) {
errno = ETIME;
return -1;
}
return ret;
}
>
> >> +}
> >> +
> >> +static inline int sync_merge(const char *name, int fd1, int fd2)
> >> +{
> >> + struct sync_merge_data data = {};
> >> + int err;
> >
> > What I liked was doing
> >
> > if (fd2 < 0)
> > return dup(fd1);
> >
> > if (fd1 < 0)
> > return dup(fd2);
> >
> > That makes accumulating the fences in the caller much easier (i.e. they
> > start with
> > batch.fence_in = -1;
> > then
> > batch.fence_in = sync_merge(batch.fence_in, fence);
> > finished by
> > execbuf(&batch);
> > close(batch.fence_in);
> > batch.fence_in = -1;
>
> I guess that would end up ignoring the fence name.. although not sure
> that I care. But probably we should either make the android version
> behave the same, or pick new names for these fxns. I think having
> same names but slightly different behaviour would be confusing.
>
> Oh, and now that I'm actually looking at that code, the extra null
> terminator bit after the strncpy() is kinda unneeded.. should just
> do:
>
> strncpy(data.name, name, sizeof(data.name));
>
> (without the -1) instead
>
> BR,
> -R
>
> > -Chris
> >
> > --
> > Chris Wilson, Intel Open Source Technology Centre
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