linux-stable.git/include/net/page_pool, branch linux-6.10.y

page_pool: fix &page_pool_params kdoc issues

2024-05-28T00:00:22+00:00

After the tagged commit, @netdev got documented twice and the kdoc
script didn't notice that. Remove the second description added later
and move the initial one according to the field position.

After merging commit 5f8e4007c10d ("kernel-doc: fix
struct_group_tagged() parsing"), kdoc requires to describe struct
groups as well. &page_pool_params has 2 struct groups which
generated new warnings, describe them to resolve this.

Fixes: 403f11ac9ab7 ("page_pool: don't use driver-set flags field directly")
Signed-off-by: Alexander Lobakin 
Link: https://lore.kernel.org/r/20240524112859.2757403-1-aleksander.lobakin@intel.com
Signed-off-by: Jakub Kicinski

Merge tag 'dma-mapping-6.10-2024-05-20' of git://git.infradead.org/users/hch/dma-mapping

2024-05-20T17:23:39+00:00

Pull dma-mapping updates from Christoph Hellwig:

 - optimize DMA sync calls when they are no-ops (Alexander Lobakin)

 - fix swiotlb padding for untrusted devices (Michael Kelley)

 - add documentation for swiotb (Michael Kelley)

* tag 'dma-mapping-6.10-2024-05-20' of git://git.infradead.org/users/hch/dma-mapping:
  dma: fix DMA sync for drivers not calling dma_set_mask*()
  xsk: use generic DMA sync shortcut instead of a custom one
  page_pool: check for DMA sync shortcut earlier
  page_pool: don't use driver-set flags field directly
  page_pool: make sure frag API fields don't span between cachelines
  iommu/dma: avoid expensive indirect calls for sync operations
  dma: avoid redundant calls for sync operations
  dma: compile-out DMA sync op calls when not used
  iommu/dma: fix zeroing of bounce buffer padding used by untrusted devices
  swiotlb: remove alloc_size argument to swiotlb_tbl_map_single()
  Documentation/core-api: add swiotlb documentation

page_pool: don't use driver-set flags field directly

2024-05-07T11:29:54+00:00

page_pool::p is driver-defined params, copied directly from the
structure passed to page_pool_create(). The structure isn't meant
to be modified by the Page Pool core code and this even might look
confusing[0][1].
In order to be able to alter some flags, let's define our own, internal
fields the same way as the already existing one (::has_init_callback).
They are defined as bits in the driver-set params, leave them so here
as well, to not waste byte-per-bit or so. Almost 30 bits are still free
for future extensions.
We could've defined only new flags here or only the ones we may need
to alter, but checking some flags in one place while others in another
doesn't sound convenient or intuitive. ::flags passed by the driver can
now go to the "slow" PP params.

Suggested-by: Jakub Kicinski 
Link[0]: https://lore.kernel.org/netdev/20230703133207.4f0c54ce@kernel.org
Suggested-by: Alexander Duyck 
Link[1]: https://lore.kernel.org/netdev/CAKgT0UfZCGnWgOH96E4GV3ZP6LLbROHM7SHE8NKwq+exX+Gk_Q@mail.gmail.com
Signed-off-by: Alexander Lobakin 
Signed-off-by: Christoph Hellwig

page_pool: make sure frag API fields don't span between cachelines

2024-05-07T11:29:54+00:00

After commit 5027ec19f104 ("net: page_pool: split the page_pool_params
into fast and slow") that made &page_pool contain only "hot" params at
the start, cacheline boundary chops frag API fields group in the middle
again.
To not bother with this each time fast params get expanded or shrunk,
let's just align them to `4 * sizeof(long)`, the closest upper pow-2 to
their actual size (2 longs + 1 int). This ensures 16-byte alignment for
the 32-bit architectures and 32-byte alignment for the 64-bit ones,
excluding unnecessary false-sharing.
::page_state_hold_cnt is used quite intensively on hotpath no matter if
frag API is used, so move it to the newly created hole in the first
cacheline.

Signed-off-by: Alexander Lobakin 
Signed-off-by: Christoph Hellwig

page_pool: add DMA-sync-for-CPU inline helper

2024-04-24T18:06:25+00:00

Each driver is responsible for syncing buffers written by HW for CPU
before accessing them. Almost each PP-enabled driver uses the same
pattern, which could be shorthanded into a static inline to make driver
code a little bit more compact.
Introduce a simple helper which performs DMA synchronization for the
size passed from the driver. It can be used even when the pool doesn't
manage DMA-syncs-for-device, just make sure the page has a correct DMA
address set via page_pool_set_dma_addr().

Signed-off-by: Alexander Lobakin 
Reviewed-by: Ilias Apalodimas 
Signed-off-by: Tony Nguyen

page_pool: constify some read-only function arguments

2024-04-24T18:06:25+00:00

There are several functions taking pointers to data they don't modify.
This includes statistics fetching, page and page_pool parameters, etc.
Constify the pointers, so that call sites will be able to pass const
pointers as well.
No functional changes, no visible changes in functions sizes.

Reviewed-by: Ilias Apalodimas 
Signed-off-by: Alexander Lobakin 
Signed-off-by: Tony Nguyen

net: page_pool: fix recycle stats for system page_pool allocator

2024-02-19T20:30:27+00:00

Use global percpu page_pool_recycle_stats counter for system page_pool
allocator instead of allocating a separate percpu variable for each
(also percpu) page pool instance.

Reviewed-by: Toke Hoiland-Jorgensen 
Signed-off-by: Lorenzo Bianconi 
Reviewed-by: Alexander Lobakin 
Link: https://lore.kernel.org/r/87f572425e98faea3da45f76c3c68815c01a20ee.1708075412.git.lorenzo@kernel.org
Signed-off-by: Jakub Kicinski

page_pool: disable direct recycling based on pool->cpuid on destroy

2024-02-19T19:48:00+00:00

Now that direct recycling is performed basing on pool->cpuid when set,
memory leaks are possible:

1. A pool is destroyed.
2. Alloc cache is emptied (it's done only once).
3. pool->cpuid is still set.
4. napi_pp_put_page() does direct recycling basing on pool->cpuid.
5. Now alloc cache is not empty, but it won't ever be freed.

In order to avoid that, rewrite pool->cpuid to -1 when unlinking NAPI to
make sure no direct recycling will be possible after emptying the cache.
This involves a bit of overhead as pool->cpuid now must be accessed
via READ_ONCE() to avoid partial reads.
Rename page_pool_unlink_napi() -> page_pool_disable_direct_recycling()
to reflect what it actually does and unexport it.

Signed-off-by: Alexander Lobakin 
Reviewed-by: Toke Høiland-Jørgensen 
Link: https://lore.kernel.org/r/20240215113905.96817-1-aleksander.lobakin@intel.com
Signed-off-by: Jakub Kicinski

net: add generic percpu page_pool allocator

2024-02-14T03:22:30+00:00

Introduce generic percpu page_pools allocator.
Moreover add page_pool_create_percpu() and cpuid filed in page_pool struct
in order to recycle the page in the page_pool "hot" cache if
napi_pp_put_page() is running on the same cpu.
This is a preliminary patch to add xdp multi-buff support for xdp running
in generic mode.

Acked-by: Jesper Dangaard Brouer 
Reviewed-by: Toke Hoiland-Jorgensen 
Signed-off-by: Lorenzo Bianconi 
Link: https://lore.kernel.org/r/80bc4285228b6f4220cd03de1999d86e46e3fcbd.1707729884.git.lorenzo@kernel.org
Signed-off-by: Jakub Kicinski

skbuff: Optimization of SKB coalescing for page pool

2023-12-17T10:56:33+00:00

In order to address the issues encountered with commit 1effe8ca4e34
("skbuff: fix coalescing for page_pool fragment recycling"), the
combination of the following condition was excluded from skb coalescing:

from->pp_recycle = 1
from->cloned = 1
to->pp_recycle = 1

However, with page pool environments, the aforementioned combination can
be quite common(ex. NetworkMananger may lead to the additional
packet_type being registered, thus the cloning). In scenarios with a
higher number of small packets, it can significantly affect the success
rate of coalescing. For example, considering packets of 256 bytes size,
our comparison of coalescing success rate is as follows:

Without page pool: 70%
With page pool: 13%

Consequently, this has an impact on performance:

Without page pool: 2.57 Gbits/sec
With page pool: 2.26 Gbits/sec

Therefore, it seems worthwhile to optimize this scenario and enable
coalescing of this particular combination. To achieve this, we need to
ensure the correct increment of the "from" SKB page's page pool
reference count (pp_ref_count).

Following this optimization, the success rate of coalescing measured in
our environment has improved as follows:

With page pool: 60%

This success rate is approaching the rate achieved without using page
pool, and the performance has also been improved:

With page pool: 2.52 Gbits/sec

Below is the performance comparison for small packets before and after
this optimization. We observe no impact to packets larger than 4K.

packet size     before      after       improved
(bytes)         (Gbits/sec) (Gbits/sec)
128             1.19        1.27        7.13%
256             2.26        2.52        11.75%
512             4.13        4.81        16.50%
1024            6.17        6.73        9.05%
2048            14.54       15.47       6.45%
4096            25.44       27.87       9.52%

Signed-off-by: Liang Chen 
Reviewed-by: Yunsheng Lin 
Suggested-by: Jason Wang 
Reviewed-by: Mina Almasry 
Signed-off-by: David S. Miller