mbox series

[0/2] bpf: Allow bpf_for/bpf_repeat while holding spin

Message ID 20250101203731.1651981-1-emil@etsalapatis.com (mailing list archive)
Headers show
Series bpf: Allow bpf_for/bpf_repeat while holding spin | expand

Message

Emil Tsalapatis Jan. 1, 2025, 8:37 p.m. UTC 
From: Emil Tsalapatis (Meta) <emil@etsalapatis.com>

In BPF programs, kfunc calls while holding a lock are not allowed
because kfuncs may sleep by default. The exception to this rule are the
functions in special_kfunc_list, which are guaranteed to not sleep. The
bpf_iter_num_* functions used by the bpf_for and bpf_repeat macros make
no function calls themselves, and as such are guaranteed to not sleep.
Add them to special_kfunc_list to allow them within BPF spinlock
critical sections.

Signed-off-by: Emil Tsalapatis (Meta) <emil@etsalapatis.com>

Emil Tsalapatis (2):
  bpf: Allow bpf_for/bpf_repeat calls while holding a spinlock
  selftests/bpf: test bpf_for within spin lock section

 kernel/bpf/verifier.c                         | 20 +++++++++++++-
 .../selftests/bpf/progs/verifier_spin_lock.c  | 26 +++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)