libbpf: streamline netlink-based XDP APIs #2437
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Master branch: 4e95074 |
Introduce 4 new netlink-based XDP APIs for attaching, detaching, and querying XDP programs: - bpf_xdp_attach; - bpf_xdp_detach; - bpf_xdp_query; - bpf_xdp_query_id. These APIs replace bpf_set_link_xdp_fd, bpf_set_link_xdp_fd_opts, bpf_get_link_xdp_id, and bpf_get_link_xdp_info APIs ([0]). The latter don't follow a consistent naming pattern and some of them use non-extensible approaches (e.g., struct xdp_link_info which can't be modified without breaking libbpf ABI). The approach I took with these low-level XDP APIs is similar to what we did with low-level TC APIs. There is a nice duality of bpf_tc_attach vs bpf_xdp_attach, and so on. I left bpf_xdp_attach() to support detaching when -1 is specified for prog_fd for generality and convenience, but bpf_xdp_detach() is preferred due to clearer naming and associated semantics. Both bpf_xdp_attach() and bpf_xdp_detach() accept the same opts struct allowing to specify expected old_prog_fd. While doing the refactoring, I noticed that old APIs require users to specify opts with old_fd == -1 to declare "don't care about already attached XDP prog fd" condition. Otherwise, FD 0 is assumed, which is essentially never an intended behavior. So I made this behavior consistent with other kernel and libbpf APIs, in which zero FD means "no FD". This seems to be more in line with the latest thinking in BPF land and should cause less user confusion, hopefully. For querying, I left two APIs, both more generic bpf_xdp_query() allowing to query multiple IDs and attach mode, but also a specialization of it, bpf_xdp_query_id(), which returns only requested prog_id. Uses of prog_id returning bpf_get_link_xdp_id() were so prevalent across selftests and samples, that it seemed a very common use case and using bpf_xdp_query() for doing it felt very cumbersome with a highly branches if/else chain based on flags and attach mode. Old APIs are scheduled for deprecation in libbpf 0.8 release. [0] Closes: libbpf/libbpf#309 Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Switch to new bpf_xdp_attach() API to avoid deprecation warnings. Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Switch to using new bpf_xdp_*() APIs across all selftests. Take advantage of a more straightforward and user-friendly semantics of old_prog_fd (0 means "don't care") in few places. Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
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Master branch: 1058b6a |
Use new bpf_xdp_*() APIs across all XDP-related BPF samples. Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=606810 irrelevant now. Closing PR. |
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Christoph reports a page allocator splat triggered by xfstests: generic/176 214s ... [ 1204.507931] run fstests generic/176 at 2024-05-27 12:52:30 XFS (nvme0n1): Mounting V5 Filesystem cd936307-415f-48a3-b99d-a2d52ae1f273 XFS (nvme0n1): Ending clean mount XFS (nvme1n1): Mounting V5 Filesystem ab3ee1a4-af62-4934-9a6a-6c2fde321850 XFS (nvme1n1): Ending clean mount XFS (nvme1n1): Unmounting Filesystem ab3ee1a4-af62-4934-9a6a-6c2fde321850 XFS (nvme1n1): Mounting V5 Filesystem 7099b02d-9c58-4d1d-be1d-2cc472d12cd9 XFS (nvme1n1): Ending clean mount ------------[ cut here ]------------ page type is 3, passed migratetype is 1 (nr=512) WARNING: CPU: 0 PID: 509870 at mm/page_alloc.c:645 expand+0x1c5/0x1f0 Modules linked in: i2c_i801 crc32_pclmul i2c_smbus [last unloaded: scsi_debug] CPU: 0 PID: 509870 Comm: xfs_io Not tainted 6.10.0-rc1+ kernel-patches#2437 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:expand+0x1c5/0x1f0 Code: 05 16 70 bf 02 01 e8 ca fc ff ff 8b 54 24 34 44 89 e1 48 c7 c7 80 a2 28 83 48 89 c6 b8 01 00 3 RSP: 0018:ffffc90003b2b968 EFLAGS: 00010082 RAX: 0000000000000000 RBX: ffffffff83fa9480 RCX: 0000000000000000 RDX: 0000000000000005 RSI: 0000000000000027 RDI: 00000000ffffffff RBP: 00000000001f2600 R08: 00000000fffeffff R09: 0000000000000001 R10: 0000000000000000 R11: ffffffff83676200 R12: 0000000000000009 R13: 0000000000000200 R14: 0000000000000001 R15: ffffea0007c98000 FS: 00007f72ca3d5780(0000) GS:ffff8881f9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f72ca1fff38 CR3: 00000001aa0c6002 CR4: 0000000000770ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff07f0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <TASK> ? __warn+0x7b/0x120 ? expand+0x1c5/0x1f0 ? report_bug+0x191/0x1c0 ? handle_bug+0x3c/0x80 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? expand+0x1c5/0x1f0 ? expand+0x1c5/0x1f0 __rmqueue_pcplist+0x3a9/0x730 get_page_from_freelist+0x7a0/0xf00 __alloc_pages_noprof+0x153/0x2e0 __folio_alloc_noprof+0x10/0xa0 __filemap_get_folio+0x16b/0x370 iomap_write_begin+0x496/0x680 While trying to service a movable allocation (page type 1), the page allocator runs into a two-pageblock buddy on the movable freelist whose second block is typed as highatomic (page type 3). This inconsistency is caused by the highatomic reservation system operating on single pageblocks, while MAX_ORDER can be bigger than that - in this configuration, pageblock_order is 9 while MAX_PAGE_ORDER is 10. The test case is observed to make several adjacent order-3 requests with __GFP_DIRECT_RECLAIM cleared, which marks the surrounding block as highatomic. Upon freeing, the blocks merge into an order-10 buddy. When the highatomic pool is drained later on, this order-10 buddy gets moved back to the movable list, but only the first pageblock is marked movable again. A subsequent expand() of this buddy warns about the tail being of a different type. This is a long-standing bug that's surfaced by the recent block type warnings added to the allocator. The consequences seem mostly benign, it just results in odd behavior: the highatomic tail blocks are not properly drained, instead they end up on the movable list first, then go back to the highatomic list after an alloc-free cycle. To fix this, make the highatomic reservation code aware that allocations/buddies can be larger than a pageblock. While it's an old quirk, the recently added type consistency warnings seem to be the most prominent consequence of it. Set the Fixes: tag accordingly to highlight this backporting dependency. Link: https://lkml.kernel.org/r/20240530114203.GA1222079@cmpxchg.org Fixes: e0932b6 ("mm: page_alloc: consolidate free page accounting") Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Christoph Hellwig <hch@infradead.org> Reviewed-by: Zi Yan <ziy@nvidia.com> Tested-by: Christoph Hellwig <hch@lst.de> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Pull request for series with
subject: libbpf: streamline netlink-based XDP APIs
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=606810