From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
Hans Verkuil <hans.verkuil@cisco.com>,
Tomasz Figa <tfiga@chromium.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Kyungmin Park <kyungmin.park@samsung.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Sakari Ailus <sakari.ailus@iki.fi>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Pawel Osciak <posciak@chromium.org>,
linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCHv4 04/11] videobuf2: add queue memory consistency parameter
Date: Sat, 7 Mar 2020 16:50:46 +0900 [thread overview]
Message-ID: <20200307075046.GC176460@google.com> (raw)
In-Reply-To: <7ab74b32-441d-1a1a-0112-6c4d0c0b900c@xs4all.nl>
On (20/03/06 15:04), Hans Verkuil wrote:
[..]
> > +static bool verify_consistency_attr(struct vb2_queue *q, bool consistent_mem)
> > +{
> > + bool queue_attr = q->dma_attrs & DMA_ATTR_NON_CONSISTENT;
> > +
> > + if (consistent_mem != queue_attr) {
>
> This is the wrong way around!
>
> It's much better to write it like this:
>
> bool queue_is_consistent = !(q->dma_attrs & DMA_ATTR_NON_CONSISTENT);
>
> if (consistent_mem != queue_is_consistent) {
Hmm... That's a great catch. Thanks for spotting this.
Puzzled, how come I've never seen problems.
> What concerns me more is that this means that this series has not been
> tested properly. I found this when testing with v4l2-compliance and vivid.
I fully understand your concerns. Give me a moment to figure
out what's going on...
OK.
Apparently, the user-space I'm using for tests, utilizes different
call path. vb2_core_create_bufs() is never even invoked. Hence queue
consistency vs. request consistency checks are not performed.
What happens, instead, is v4l_reqbufs()->vb2_core_reqbufs() path.
It orphans existing buffers (if any), sets queue memory model, sets
queue consistency model (DMA attr), then allocates buffers.
On my test environment, I see that vb2_core_reqbufs() orphans the
buffers, but it's always due to "*count == 0 || q->num_buffers != 0"
conditions. The user-space I'm using does not twist queue ->memory
or consistency attr, so the tests I'm running are limited in scenarios.
verify_consistency_attr() is not on the list of reasons to orphan
allocated buffer. It probably should be, tho.
===
diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index afb3c21a5902..d6b1d32bef3f 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -730,7 +730,8 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
}
if (*count == 0 || q->num_buffers != 0 ||
- (q->memory != VB2_MEMORY_UNKNOWN && q->memory != memory)) {
+ (q->memory != VB2_MEMORY_UNKNOWN && q->memory != memory) ||
+ !verify_consistency_attr(q, consistent_mem)) {
/*
* We already have buffers allocated, so first check if they
* are not in use and can be freed.
===
> > + dprintk(1, "memory consistency model mismatch\n");
> > + return false;
> > + }
> > + return true;
> > +}
> > +
> > int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
> > - unsigned int *count, unsigned requested_planes,
> > - const unsigned requested_sizes[])
> > + bool consistent_mem, unsigned int *count,
> > + unsigned requested_planes,
> > + const unsigned requested_sizes[])
>
> Use 'unsigned int' in the two lines above, as per checkpatch suggestion.
OK, will do.
This comes from the original code. There are 'unsigned'-s in the
existing code, I saw it and didn't want to modify, in order to keep
diffstats shorter.
-ss
next prev parent reply other threads:[~2020-03-07 7:50 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-02 4:12 [PATCHv4 00/11] Implement V4L2_BUF_FLAG_NO_CACHE_* flags Sergey Senozhatsky
2020-03-02 4:12 ` [PATCHv4 01/11] videobuf2: add cache management members Sergey Senozhatsky
2020-03-06 13:57 ` Hans Verkuil
2020-03-07 5:22 ` Sergey Senozhatsky
2020-03-07 9:46 ` Sergey Senozhatsky
2020-03-07 10:10 ` Hans Verkuil
2020-03-07 11:28 ` Sergey Senozhatsky
2020-03-07 11:47 ` Hans Verkuil
2020-03-09 3:27 ` Sergey Senozhatsky
2020-03-09 3:44 ` Sergey Senozhatsky
2020-03-09 7:21 ` Hans Verkuil
2020-03-09 7:25 ` Sergey Senozhatsky
2020-03-09 7:28 ` Hans Verkuil
2020-03-09 7:39 ` Sergey Senozhatsky
2020-03-09 8:58 ` Tomasz Figa
2020-03-09 9:08 ` Sergey Senozhatsky
2020-03-09 9:17 ` Tomasz Figa
2020-03-09 9:29 ` Sergey Senozhatsky
2020-03-09 4:03 ` Sergey Senozhatsky
2020-03-09 7:17 ` Hans Verkuil
2020-03-02 4:12 ` [PATCHv4 02/11] videobuf2: handle V4L2 buffer cache flags Sergey Senozhatsky
2020-03-02 4:12 ` [PATCHv4 03/11] videobuf2: add V4L2_FLAG_MEMORY_NON_CONSISTENT flag Sergey Senozhatsky
2020-03-06 13:58 ` Hans Verkuil
2020-03-07 8:09 ` Sergey Senozhatsky
2020-03-02 4:12 ` [PATCHv4 04/11] videobuf2: add queue memory consistency parameter Sergey Senozhatsky
2020-03-06 14:04 ` Hans Verkuil
2020-03-07 7:50 ` Sergey Senozhatsky [this message]
2020-03-07 10:03 ` Hans Verkuil
2020-03-20 13:46 ` Dafna Hirschfeld
2020-03-24 2:39 ` Sergey Senozhatsky
2020-03-24 10:17 ` Ezequiel Garcia
2020-03-25 2:32 ` Sergey Senozhatsky
2020-03-27 11:27 ` Tomasz Figa
2020-03-02 4:12 ` [PATCHv4 05/11] videobuf2: handle V4L2_FLAG_MEMORY_NON_CONSISTENT flag Sergey Senozhatsky
2020-03-06 15:30 ` Hans Verkuil
2020-03-07 7:51 ` Sergey Senozhatsky
2020-03-07 9:38 ` Sergey Senozhatsky
2020-03-07 10:05 ` Hans Verkuil
2020-03-02 4:12 ` [PATCHv4 06/11] videobuf2: factor out planes prepare/finish functions Sergey Senozhatsky
2020-03-02 4:12 ` [PATCHv4 07/11] videobuf2: do not sync caches when we are allowed not to Sergey Senozhatsky
2020-03-02 4:12 ` [PATCHv4 08/11] videobuf2: check ->synced flag in prepare() and finish() Sergey Senozhatsky
2020-03-02 4:12 ` [PATCHv4 09/11] videobuf2: add begin/end cpu_access callbacks to dma-contig Sergey Senozhatsky
2020-03-02 4:12 ` [PATCHv4 10/11] videobuf2: add begin/end cpu_access callbacks to dma-sg Sergey Senozhatsky
2020-03-06 14:04 ` Hans Verkuil
2020-03-07 5:26 ` Sergey Senozhatsky
2020-03-07 9:32 ` Hans Verkuil
2020-03-07 9:39 ` Sergey Senozhatsky
2020-03-02 4:12 ` [PATCHv4 11/11] videobuf2: don't test db_attach in dma-contig prepare and finish Sergey Senozhatsky
2020-03-06 14:18 ` [PATCHv4 00/11] Implement V4L2_BUF_FLAG_NO_CACHE_* flags Hans Verkuil
2020-03-07 8:08 ` Sergey Senozhatsky
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