forked from torvalds/linux
-
Notifications
You must be signed in to change notification settings - Fork 1
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Implement first open-coded iterator type over a range of integers. It's public API consists of: - bpf_iter_num_new() constructor, which accepts [start, end) range (that is, start is inclusive, end is exclusive). - bpf_iter_num_next() which will keep returning read-only pointer to int until the range is exhausted, at which point NULL will be returned. If bpf_iter_num_next() is kept calling after this, NULL will be persistently returned. - bpf_iter_num_destroy() destructor, which needs to be called at some point to clean up iterator state. BPF verifier enforces that iterator destructor is called at some point before BPF program exits. Note that `start = end = X` is a valid combination to setup empty iterator. bpf_iter_num_new() will return 0 (success) for any such combination. If bpf_iter_num_new() detects invalid combination of input arguments, it returns error, resets iterator state to, effectively, empty iterator, so any subsequent call to bpf_iter_num_next() will keep returning NULL. BPF verifier has no knowledge that returned integers are in the [start, end) value range, as both `start` and `end` are not statically known/enforced, they are runtime values only. While implementation is pretty trivial, some care needs to be taken to avoid overflows and underflows. Subsequent selftests will validate correctness of [start, end) semantics, especially around extremes (INT_MIN and INT_MAX). Similarly to bpf_loop(), we enforce that no more than BPF_MAX_LOOPS can be specified. bpf_iter_num_{new,next,destroy}() is a logical evolution from bounded BPF loops and bpf_loop() helper and is the basis for implementing ergonomic BPF loops with no statically known or verified bounds. Subsequent patches implement bpf_for() macro, demonstrating how this can be wrapped into something that works and feels like a normal for() loop in C language. Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
- Loading branch information
1 parent
8f263e1
commit 19acf9c
Showing
5 changed files
with
95 additions
and
2 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters