lib/scatterlist: Fix wrong update of orig_nents

orig_nents should represent the number of entries with pages,
but __sg_alloc_table_from_pages sets orig_nents as the number of
total entries in the ta

lib/scatterlist: Fix wrong update of orig_nents

orig_nents should represent the number of entries with pages,
but __sg_alloc_table_from_pages sets orig_nents as the number of
total entries in the table. This is wrong when the API is used for
dynamic allocation where not all the table entries are mapped with
pages. It wasn't observed until now, since RDMA umem who uses this
API in the dynamic form doesn't use orig_nents implicit or explicit
by the scatterlist APIs.

Fix it by changing the append API to track the SG append table
state and have an API to free the append table according to the
total number of entries in the table.
Now all APIs set orig_nents as number of enries with pages.

Fixes: 07da1223ec93 ("lib/scatterlist: Add support in dynamic allocation of SG table from pages")
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Maor Gottlieb <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

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lib/scatterlist: Provide a dedicated function to support table append

RDMA is the only in-kernel user that uses __sg_alloc_table_from_pages to
append pages dynamically. In the next patch. That mode

lib/scatterlist: Provide a dedicated function to support table append

RDMA is the only in-kernel user that uses __sg_alloc_table_from_pages to
append pages dynamically. In the next patch. That mode will be extended
and that function will get more parameters. So separate it into a unique
function to make such change more clear.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Maor Gottlieb <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

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tools/testing/scatterlist: Fix overflow of max segment size

Because SCATTERLIST_MAX_SEGMENT was removed and replaced with UINT_MAX,
the test overflows the max_sgement variable. Remove this case.

Fi

tools/testing/scatterlist: Fix overflow of max segment size

Because SCATTERLIST_MAX_SEGMENT was removed and replaced with UINT_MAX,
the test overflows the max_sgement variable. Remove this case.

Fixes: 7a60c2dd0f57 ("drm: Remove SCATTERLIST_MAX_SEGMENT")
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Maor Gottlieb <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

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tools/testing/scatterlist: Test dynamic __sg_alloc_table_from_pages

Add few cases to test the dynamic allocation flow of
__sg_alloc_table_from_pages.

Link: https://lore.kernel.org/r/20201115120650.

tools/testing/scatterlist: Test dynamic __sg_alloc_table_from_pages

Add few cases to test the dynamic allocation flow of
__sg_alloc_table_from_pages.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Maor Gottlieb <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

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tools/testing/scatterlist: Fix test to compile and run

Add missing define of ALIGN_DOWN to make the test build and run. In
addition, __sg_alloc_table_from_pages now support unaligned maximum
segmen

tools/testing/scatterlist: Fix test to compile and run

Add missing define of ALIGN_DOWN to make the test build and run. In
addition, __sg_alloc_table_from_pages now support unaligned maximum
segment, so adapt the test result accordingly.

Fixes: 07da1223ec93 ("lib/scatterlist: Add support in dynamic allocation of SG table from pages")
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Maor Gottlieb <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

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drm: Remove SCATTERLIST_MAX_SEGMENT

Since commit 9a40401cfa13 ("lib/scatterlist: Do not limit max_segment to
PAGE_ALIGNED values") the max_segment input to sg_alloc_table_from_pages()
does not have

drm: Remove SCATTERLIST_MAX_SEGMENT

Since commit 9a40401cfa13 ("lib/scatterlist: Do not limit max_segment to
PAGE_ALIGNED values") the max_segment input to sg_alloc_table_from_pages()
does not have to be any special value. The new algorithm will always
create something less than what the user provides. Thus eliminate this
confusing constant.

- vmwgfx should use the HW capability, not mix in the OS page size for
calling dma_set_max_seg_size()

- i915 uses i915_sg_segment_size() both for sg_alloc_table_from_pages
and for some open coded sgl construction. This doesn't change the value
since rounddown(size, UINT_MAX) == SCATTERLIST_MAX_SEGMENT

- drm_prime_pages_to_sg uses it as a default if max_segment is zero,
UINT_MAX is fine to use directly.

Cc: Gerd Hoffmann <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Thomas Hellstrom <[email protected]>
Cc: Qian Cai <[email protected]>
Cc: "Ursulin, Tvrtko" <[email protected]>
Suggested-by: Christoph Hellwig <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

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lib/scatterlist: Add support in dynamic allocation of SG table from pages

Extend __sg_alloc_table_from_pages to support dynamic allocation of
SG table from pages. It should be used by drivers that c

lib/scatterlist: Add support in dynamic allocation of SG table from pages

Extend __sg_alloc_table_from_pages to support dynamic allocation of
SG table from pages. It should be used by drivers that can't supply
all the pages at one time.

This function returns the last populated SGE in the table. Users should
pass it as an argument to the function from the second call and forward.
As before, nents will be equal to the number of populated SGEs (chunks).

With this new extension, drivers can benefit the optimization of merging
contiguous pages without a need to allocate all pages in advance and
hold them in a large buffer.

E.g. with the Infiniband driver that allocates a single page for hold the
pages. For 1TB memory registration, the temporary buffer would consume only
4KB, instead of 2GB.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Maor Gottlieb <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

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tools/testing/scatterlist: Show errors in human readable form

Instead of just asserting dump some more useful info about what the test
saw versus what it expected to see.

Link: https://lore.kernel.

tools/testing/scatterlist: Show errors in human readable form

Instead of just asserting dump some more useful info about what the test
saw versus what it expected to see.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tvrtko Ursulin <[email protected]>
Cc: Maor Gottlieb <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

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tools/testing/scatterlist: Test new __sg_alloc_table_from_pages

Exercise the new __sg_alloc_table_from_pages API (and through
it also the old sg_alloc_table_from_pages), checking that the
created ta

tools/testing/scatterlist: Test new __sg_alloc_table_from_pages

Exercise the new __sg_alloc_table_from_pages API (and through
it also the old sg_alloc_table_from_pages), checking that the
created table has the expected number of segments depending on
the sequence of input pages and other conditions.

v2: Move to data driven for readability.
v3: Add some more testcases and -fsanitize=undefined. (Chris Wilson)

Signed-off-by: Tvrtko Ursulin <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: [email protected]
Reviewed-by: Chris Wilson <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
[tursulin: whitespace fixup]

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