bpf: avoid locks in bpf_timer and bpf_wq #6299
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Move logic for updating callback and prog owning it into a separate function: bpf_async_update_callback(). This helps to localize data race and will be reused in the next patches. Acked-by: Eduard Zingerman <[email protected]> Signed-off-by: Mykyta Yatsenko <[email protected]>
Move the logic that swaps the bpf_prog in struct bpf_async_cb into a dedicated helper to make follow-up patches simpler. Acked-by: Eduard Zingerman <[email protected]> Signed-off-by: Mykyta Yatsenko <[email protected]>
Move the timer deletion logic into a dedicated bpf_timer_delete() helper so it can be reused by later patches. Acked-by: Eduard Zingerman <[email protected]> Signed-off-by: Mykyta Yatsenko <[email protected]>
To manage lifetime guarantees of the struct bpf_async_cb, when no lock serializes mutations, introduce refcnt field into the struct. Implement bpf_async_tryget() and bpf_async_put() to handle the refcnt. Signed-off-by: Mykyta Yatsenko <[email protected]>
Remove lock from bpf_async_cb, refactor bpf_timer and bpf_wq kfuncs and helpers to run without it. bpf_async_cb lifetime is managed by the refcnt and RCU, so every function that uses it has to apply RCU guard. cancel_and_free() path detaches bpf_async_cb from the map value (struct bpf_async_kern) and sets the state to the terminal BPF_ASYNC_FREED atomically, concurrent readers may operate on detached bpf_async_cb safely under RCU read lock. Guarantee safe bpf_prog drop from the bpf_async_cb by handling BPF_ASYNC_FREED state in bpf_async_update_callback(). Signed-off-by: Mykyta Yatsenko <[email protected]>
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Upstream branch: 4cb4897 |
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=1019973 expired. Closing PR. |
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Pull request for series with
subject: bpf: avoid locks in bpf_timer and bpf_wq
version: 2
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=1019973