| Message ID | 20230316054028.88924-1-void@manifault.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Make struct bpf_cpumask RCU safe | expand |
Hello: This series was applied to bpf/bpf-next.git (master) by Alexei Starovoitov <ast@kernel.org>: On Thu, 16 Mar 2023 00:40:23 -0500 you wrote: > The struct bpf_cpumask type is currently not RCU safe. It uses the > bpf_mem_cache_{alloc,free}() APIs to allocate and release cpumasks, and > those allocations may be reused before an RCU grace period has elapsed. > We want to be able to enable using this pattern in BPF programs: > > private(MASK) static struct bpf_cpumask __kptr *global; > > [...] Here is the summary with links: - [bpf-next,v2,1/5] bpf: Free struct bpf_cpumask in call_rcu handler https://git.kernel.org/bpf/bpf-next/c/77473d1a962f - [bpf-next,v2,2/5] bpf: Mark struct bpf_cpumask as rcu protected https://git.kernel.org/bpf/bpf-next/c/63d2d83d21a6 - [bpf-next,v2,3/5] bpf/selftests: Test using global cpumask kptr with RCU https://git.kernel.org/bpf/bpf-next/c/a5a197df58c4 - [bpf-next,v2,4/5] bpf: Remove bpf_cpumask_kptr_get() kfunc https://git.kernel.org/bpf/bpf-next/c/1b403ce77dfb - [bpf-next,v2,5/5] bpf,docs: Remove bpf_cpumask_kptr_get() from documentation https://git.kernel.org/bpf/bpf-next/c/fec2c6d14fd5 You are awesome, thank you!
The struct bpf_cpumask type is currently not RCU safe. It uses the bpf_mem_cache_{alloc,free}() APIs to allocate and release cpumasks, and those allocations may be reused before an RCU grace period has elapsed. We want to be able to enable using this pattern in BPF programs: private(MASK) static struct bpf_cpumask __kptr *global; int BPF_PROG(prog, ...) { struct bpf_cpumask *cpumask; bpf_rcu_read_lock(); cpumask = global; if (!cpumask) { bpf_rcu_read_unlock(); return -1; } bpf_cpumask_setall(cpumask); ... bpf_rcu_read_unlock(); } In other words, to be able to pass a kptr to KF_RCU bpf_cpumask kfuncs without requiring the acquisition and release of refcounts using bpf_cpumask_kptr_get(). This patchset enables this by making the struct bpf_cpumask type RCU safe, and removing the bpf_cpumask_kptr_get() function. --- v1: https://lore.kernel.org/all/20230316014122.678082-2-void@manifault.com/ Changelog: ---------- v1 -> v2: - Add doxygen comment for new @rcu field in struct bpf_cpumask. David Vernet (5): bpf: Free struct bpf_cpumask in call_rcu handler bpf: Mark struct bpf_cpumask as rcu protected bpf/selftests: Test using global cpumask kptr with RCU bpf: Remove bpf_cpumask_kptr_get() kfunc bpf,docs: Remove bpf_cpumask_kptr_get() from documentation Documentation/bpf/cpumasks.rst | 30 +++----- kernel/bpf/cpumask.c | 38 +++-------- kernel/bpf/verifier.c | 1 + .../selftests/bpf/prog_tests/cpumask.c | 2 +- .../selftests/bpf/progs/cpumask_common.h | 7 +- .../selftests/bpf/progs/cpumask_failure.c | 68 +++++++++++++++---- .../selftests/bpf/progs/cpumask_success.c | 29 ++++---- 7 files changed, 96 insertions(+), 79 deletions(-)