The basic idea stayed the same since the last version of those patches. The exporter can provide explicit pin/unpin functions and the importer a move_notify callback. This allows us to avoid pinning buffers while importers have a mapping for them.
In difference to the last version the locking changes were separated from this patchset and committed to drm-misc-next.
This allows drivers to implement the new locking semantics without the extra unpinned handling, but of course the changed locking semantics is still a prerequisite to the unpinned handling.
The last time this set was send out the discussion ended by questioning if the move_notify callback was really the right approach of notifying the importers that a buffer is about to change its placement. A possible alternative would be to add a special crafted fence object instead.
Let's discuss on the different approaches once more,
Christian.
All implementations are gone now.
Signed-off-by: Daniel Vetter <daniel.vetter(a)intel.com>
Cc: Sumit Semwal <sumit.semwal(a)linaro.org>
Cc: linux-media(a)vger.kernel.org
Cc: linaro-mm-sig(a)lists.linaro.org
---
include/linux/dma-buf.h | 25 -------------------------
1 file changed, 25 deletions(-)
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 7feb9c3805ae..abf5459a5b9d 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -249,31 +249,6 @@ struct dma_buf_ops {
*/
int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
- /**
- * @map:
- *
- * Maps a page from the buffer into kernel address space. The page is
- * specified by offset into the buffer in PAGE_SIZE units.
- *
- * This callback is optional.
- *
- * Returns:
- *
- * Virtual address pointer where requested page can be accessed. NULL
- * on error or when this function is unimplemented by the exporter.
- */
- void *(*map)(struct dma_buf *, unsigned long);
-
- /**
- * @unmap:
- *
- * Unmaps a page from the buffer. Page offset and address pointer should
- * be the same as the one passed to and returned by matching call to map.
- *
- * This callback is optional.
- */
- void (*unmap)(struct dma_buf *, unsigned long, void *);
-
void *(*vmap)(struct dma_buf *);
void (*vunmap)(struct dma_buf *, void *vaddr);
};
--
2.24.0
Quoting kernel test robot (2019-11-21 07:19:43)
> Greetings,
>
> 0day kernel testing robot got the below dmesg and the first bad commit is
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>
> commit 2989f6451084aed3f8cc9992477f7a9bf57a3716
> Author: Chris Wilson <chris(a)chris-wilson.co.uk>
> AuthorDate: Mon Aug 19 10:59:27 2019 +0100
> Commit: Chris Wilson <chris(a)chris-wilson.co.uk>
> CommitDate: Mon Aug 19 18:09:46 2019 +0100
That's a belated report, fixed by
commit 6ac3a0ebfcc2f0c75ca0ca6974389ce421aa5cbd
Author: Chris Wilson <chris(a)chris-wilson.co.uk>
Date: Tue Aug 20 13:21:18 2019 +0100
dmabuf: Mark up onstack timer for selftests
No?
-Chris
Semnatically it really doesn't matter where we grab the ticket. But
since the ticket is a fake lockdep lock, it matters for lockdep
validation purposes.
This means stuff like grabbing a ticket and then doing
copy_from/to_user isn't allowed anymore. This is a changed compared to
the current ttm fault handler, which doesn't bother with having a full
reservation. Since I'm looking into fixing the TODO entry in
ttm_mem_evict_wait_busy() I think that'll have to change sooner or
later anyway, better get started. A bit more context on why I'm
looking into this: For backwards compat with existing i915 gem code I
think we'll have to do full slowpath locking in the i915 equivalent of
the eviction code. And with dynamic dma-buf that will leak across
drivers, so another thing we need to standardize and make sure it's
done the same way everyway.
Unfortunately this means another full audit of all drivers:
- gem helpers: acquire_init is done right before taking locks, so no
problem. Same for acquire_fini and unlocking, which means nothing
that's not already covered by the dma_resv_lock rules will be caught
with this extension here to the acquire_ctx.
- etnaviv: An absolute massive amount of code is run between the
acquire_init and the first lock acquisition in submit_lock_objects.
But nothing that would touch user memory and could cause a fault.
Furthermore nothing that uses the ticket, so even if I missed
something, it would be easy to fix by pushing the acquire_init right
before the first use. Similar on the unlock/acquire_fini side.
- i915: Right now (and this will likely change a lot rsn) the acquire
ctx and actual locks are right next to each another. No problem.
- msm has a problem: submit_create calls acquire_init, but then
submit_lookup_objects() has a bunch of copy_from_user to do the
object lookups. That's the only thing before submit_lock_objects
call dma_resv_lock(). Despite all the copypasta to etnaviv, etnaviv
does not have this issue since it copies all the userspace structs
earlier. submit_cleanup does not have any such issues.
With the prep patch to pull out the acquire_ctx and reorder it msm
is going to be safe too.
- nouveau: acquire_init is right next to ttm_bo_reserve, so all good.
Similar on the acquire_fini/ttm_bo_unreserve side.
- ttm execbuf utils: acquire context and locking are even in the same
functions here (one function to reserve everything, the other to
unreserve), so all good.
- vc4: Another case where acquire context and locking are handled in
the same functions (one function to lock everything, the other to
unlock).
Cc: Maarten Lankhorst <maarten.lankhorst(a)linux.intel.com>
Cc: Chris Wilson <chris(a)chris-wilson.co.uk>
Cc: Christian König <christian.koenig(a)amd.com>
Cc: Sumit Semwal <sumit.semwal(a)linaro.org>
Cc: linux-media(a)vger.kernel.org
Cc: linaro-mm-sig(a)lists.linaro.org
Cc: Huang Rui <ray.huang(a)amd.com>
Cc: Eric Anholt <eric(a)anholt.net>
Cc: Ben Skeggs <bskeggs(a)redhat.com>
Cc: Alex Deucher <alexander.deucher(a)amd.com>
Cc: Rob Herring <robh(a)kernel.org>
Cc: Lucas Stach <l.stach(a)pengutronix.de>
Cc: Russell King <linux+etnaviv(a)armlinux.org.uk>
Cc: Christian Gmeiner <christian.gmeiner(a)gmail.com>
Cc: Rob Clark <robdclark(a)gmail.com>
Cc: Sean Paul <sean(a)poorly.run>
Signed-off-by: Daniel Vetter <daniel.vetter(a)intel.com>
---
drivers/dma-buf/dma-resv.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index d3c760e19991..079e38fde33a 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -100,7 +100,9 @@ static void dma_resv_list_free(struct dma_resv_list *list)
static void __init dma_resv_lockdep(void)
{
struct mm_struct *mm = mm_alloc();
+ struct ww_acquire_ctx ctx;
struct dma_resv obj;
+ int ret;
if (!mm)
return;
@@ -108,10 +110,14 @@ static void __init dma_resv_lockdep(void)
dma_resv_init(&obj);
down_read(&mm->mmap_sem);
- ww_mutex_lock(&obj.lock, NULL);
+ ww_acquire_init(&ctx, &reservation_ww_class);
+ ret = dma_resv_lock(&obj, &ctx);
+ if (ret == -EDEADLK)
+ dma_resv_lock_slow(&obj, &ctx);
fs_reclaim_acquire(GFP_KERNEL);
fs_reclaim_release(GFP_KERNEL);
ww_mutex_unlock(&obj.lock);
+ ww_acquire_fini(&ctx);
up_read(&mm->mmap_sem);
mmput(mm);
--
2.24.0
On Mon, Nov 18, 2019 at 4:23 PM kbuild test robot <lkp(a)intel.com> wrote:
>
> Hi Daniel,
>
> I love your patch! Yet something to improve:
>
> [auto build test ERROR on drm-intel/for-linux-next]
> [also build test ERROR on v5.4-rc8 next-20191115]
> [if your patch is applied to the wrong git tree, please drop us a note to help
> improve the system. BTW, we also suggest to use '--base' option to specify the
> base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
Too old tree, on latest drm-tip this compiles since udl has lots its
own dma-buf implementation. Also, the patch set will start to compile
once linux-next is open for 5.6.
Cheers, Daniel
>
> url: https://github.com/0day-ci/linux/commits/Daniel-Vetter/Retire-dma_buf_k-un-…
> base: git://anongit.freedesktop.org/drm-intel for-linux-next
> config: m68k-allmodconfig (attached as .config)
> compiler: m68k-linux-gcc (GCC) 7.4.0
> reproduce:
> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # save the attached .config to linux build tree
> GCC_VERSION=7.4.0 make.cross ARCH=m68k
>
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp(a)intel.com>
>
> All errors (new ones prefixed by >>):
>
> >> drivers/dma-buf/udmabuf.c:114:3: error: 'const struct dma_buf_ops' has no member named 'map'; did you mean 'mmap'?
> .map = kmap_udmabuf,
> ^~~
> mmap
> >> drivers/dma-buf/udmabuf.c:114:12: error: initialization from incompatible pointer type [-Werror=incompatible-pointer-types]
> .map = kmap_udmabuf,
> ^~~~~~~~~~~~
> drivers/dma-buf/udmabuf.c:114:12: note: (near initialization for 'udmabuf_ops.begin_cpu_access')
> >> drivers/dma-buf/udmabuf.c:115:3: error: 'const struct dma_buf_ops' has no member named 'unmap'; did you mean 'vunmap'?
> .unmap = kunmap_udmabuf,
> ^~~~~
> vunmap
> drivers/dma-buf/udmabuf.c:115:14: error: initialization from incompatible pointer type [-Werror=incompatible-pointer-types]
> .unmap = kunmap_udmabuf,
> ^~~~~~~~~~~~~~
> drivers/dma-buf/udmabuf.c:115:14: note: (near initialization for 'udmabuf_ops.end_cpu_access')
> cc1: some warnings being treated as errors
> --
> >> drivers/gpu/drm/udl/udl_dmabuf.c:169:3: error: 'const struct dma_buf_ops' has no member named 'map'; did you mean 'mmap'?
> .map = udl_dmabuf_kmap,
> ^~~
> mmap
> >> drivers/gpu/drm/udl/udl_dmabuf.c:169:11: error: initialization from incompatible pointer type [-Werror=incompatible-pointer-types]
> .map = udl_dmabuf_kmap,
> ^~~~~~~~~~~~~~~
> drivers/gpu/drm/udl/udl_dmabuf.c:169:11: note: (near initialization for 'udl_dmabuf_ops.release')
> >> drivers/gpu/drm/udl/udl_dmabuf.c:170:3: error: 'const struct dma_buf_ops' has no member named 'unmap'; did you mean 'vunmap'?
> .unmap = udl_dmabuf_kunmap,
> ^~~~~
> vunmap
> drivers/gpu/drm/udl/udl_dmabuf.c:170:13: error: initialization from incompatible pointer type [-Werror=incompatible-pointer-types]
> .unmap = udl_dmabuf_kunmap,
> ^~~~~~~~~~~~~~~~~
> drivers/gpu/drm/udl/udl_dmabuf.c:170:13: note: (near initialization for 'udl_dmabuf_ops.begin_cpu_access')
> cc1: some warnings being treated as errors
>
> vim +114 drivers/dma-buf/udmabuf.c
>
> fbb0de79507819 Gerd Hoffmann 2018-08-27 109
> a34852891ba45d Gerd Hoffmann 2018-09-11 110 static const struct dma_buf_ops udmabuf_ops = {
> fbb0de79507819 Gerd Hoffmann 2018-08-27 111 .map_dma_buf = map_udmabuf,
> fbb0de79507819 Gerd Hoffmann 2018-08-27 112 .unmap_dma_buf = unmap_udmabuf,
> fbb0de79507819 Gerd Hoffmann 2018-08-27 113 .release = release_udmabuf,
> fbb0de79507819 Gerd Hoffmann 2018-08-27 @114 .map = kmap_udmabuf,
> fbb0de79507819 Gerd Hoffmann 2018-08-27 @115 .unmap = kunmap_udmabuf,
> fbb0de79507819 Gerd Hoffmann 2018-08-27 116 .mmap = mmap_udmabuf,
> fbb0de79507819 Gerd Hoffmann 2018-08-27 117 };
> fbb0de79507819 Gerd Hoffmann 2018-08-27 118
>
> :::::: The code at line 114 was first introduced by commit
> :::::: fbb0de795078190a9834b3409e4b009cfb18a6d4 Add udmabuf misc device
>
> :::::: TO: Gerd Hoffmann <kraxel(a)redhat.com>
> :::::: CC: Gerd Hoffmann <kraxel(a)redhat.com>
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org Intel Corporation
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
It's unused.
10 years ago, back when 32bit was still fairly common and trying to
not exhaust vmalloc space sounded like a worthwhile goal, adding these
to dma_buf made sense.
Reality is that they simply never caught on, and nowadays everyone who
needs plenty of buffers will run in 64bit mode anyway.
Also update the docs in this area to adjust them to reality.
The actual hooks in dma_buf_ops will be removed once all the
implementations are gone.
Signed-off-by: Daniel Vetter <daniel.vetter(a)intel.com>
Cc: Sumit Semwal <sumit.semwal(a)linaro.org>
Cc: linux-media(a)vger.kernel.org
Cc: linaro-mm-sig(a)lists.linaro.org
---
drivers/dma-buf/dma-buf.c | 63 ++-------------------------------------
include/linux/dma-buf.h | 2 --
2 files changed, 3 insertions(+), 62 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index d377b4ca66bf..97988ce1d2dc 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -880,29 +880,9 @@ EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
* with calls to dma_buf_begin_cpu_access() and dma_buf_end_cpu_access()
* access.
*
- * To support dma_buf objects residing in highmem cpu access is page-based
- * using an api similar to kmap. Accessing a dma_buf is done in aligned chunks
- * of PAGE_SIZE size. Before accessing a chunk it needs to be mapped, which
- * returns a pointer in kernel virtual address space. Afterwards the chunk
- * needs to be unmapped again. There is no limit on how often a given chunk
- * can be mapped and unmapped, i.e. the importer does not need to call
- * begin_cpu_access again before mapping the same chunk again.
- *
- * Interfaces::
- * void \*dma_buf_kmap(struct dma_buf \*, unsigned long);
- * void dma_buf_kunmap(struct dma_buf \*, unsigned long, void \*);
- *
- * Implementing the functions is optional for exporters and for importers all
- * the restrictions of using kmap apply.
- *
- * dma_buf kmap calls outside of the range specified in begin_cpu_access are
- * undefined. If the range is not PAGE_SIZE aligned, kmap needs to succeed on
- * the partial chunks at the beginning and end but may return stale or bogus
- * data outside of the range (in these partial chunks).
- *
- * For some cases the overhead of kmap can be too high, a vmap interface
- * is introduced. This interface should be used very carefully, as vmalloc
- * space is a limited resources on many architectures.
+ * Since for most kernel internal dma-buf accesses need the entire buffer, a
+ * vmap interface is introduced. Note that on very old 32-bit architectures
+ * vmalloc space might be limited and result in vmap calls failing.
*
* Interfaces::
* void \*dma_buf_vmap(struct dma_buf \*dmabuf)
@@ -1052,43 +1032,6 @@ int dma_buf_end_cpu_access(struct dma_buf *dmabuf,
}
EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
-/**
- * dma_buf_kmap - Map a page of the buffer object into kernel address space. The
- * same restrictions as for kmap and friends apply.
- * @dmabuf: [in] buffer to map page from.
- * @page_num: [in] page in PAGE_SIZE units to map.
- *
- * This call must always succeed, any necessary preparations that might fail
- * need to be done in begin_cpu_access.
- */
-void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
-{
- WARN_ON(!dmabuf);
-
- if (!dmabuf->ops->map)
- return NULL;
- return dmabuf->ops->map(dmabuf, page_num);
-}
-EXPORT_SYMBOL_GPL(dma_buf_kmap);
-
-/**
- * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
- * @dmabuf: [in] buffer to unmap page from.
- * @page_num: [in] page in PAGE_SIZE units to unmap.
- * @vaddr: [in] kernel space pointer obtained from dma_buf_kmap.
- *
- * This call must always succeed.
- */
-void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
- void *vaddr)
-{
- WARN_ON(!dmabuf);
-
- if (dmabuf->ops->unmap)
- dmabuf->ops->unmap(dmabuf, page_num, vaddr);
-}
-EXPORT_SYMBOL_GPL(dma_buf_kunmap);
-
/**
* dma_buf_mmap - Setup up a userspace mmap with the given vma
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index af73f835c51c..7feb9c3805ae 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -464,8 +464,6 @@ int dma_buf_begin_cpu_access(struct dma_buf *dma_buf,
enum dma_data_direction dir);
int dma_buf_end_cpu_access(struct dma_buf *dma_buf,
enum dma_data_direction dir);
-void *dma_buf_kmap(struct dma_buf *, unsigned long);
-void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
unsigned long);
--
2.24.0
The value of sync_timeline is only incremented and all reference
usage of it is unsigned. Use unsigned type for value of
synctimeline.
Signed-off-by: Seung-Woo Kim <sw0312.kim(a)samsung.com>
---
drivers/dma-buf/sync_debug.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/dma-buf/sync_debug.h b/drivers/dma-buf/sync_debug.h
index 6176e52..ff07f0b 100644
--- a/drivers/dma-buf/sync_debug.h
+++ b/drivers/dma-buf/sync_debug.h
@@ -36,7 +36,7 @@ struct sync_timeline {
/* protected by lock */
u64 context;
- int value;
+ unsigned int value;
struct rb_root pt_tree;
struct list_head pt_list;
--
1.7.4.1