From 8b5536ad1216c47fb9b37ef2cd0cfa70d79d4645 Mon Sep 17 00:00:00 2001 From: Yunsheng Lin Date: Tue, 24 Nov 2020 18:49:28 +0800 Subject: lockdep: Introduce in_softirq lockdep assert The current semantic for napi_consume_skb() is that caller need to provide non-zero budget when calling from NAPI context, and breaking this semantic will cause hard to debug problem, because _kfree_skb_defer() need to run in atomic context in order to push the skb to the particular cpu' napi_alloc_cache atomically. So add the lockdep_assert_in_softirq() to assert when the running context is not in_softirq, in_softirq means softirq is serving or BH is disabled, which has a ambiguous semantics due to the BH disabled confusion, so add a comment to emphasize that. And the softirq context can be interrupted by hard IRQ or NMI context, lockdep_assert_in_softirq() need to assert about hard IRQ or NMI context too. Suggested-by: Jakub Kicinski Signed-off-by: Yunsheng Lin Signed-off-by: Jakub Kicinski --- include/linux/lockdep.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'include/linux/lockdep.h') diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index f5594879175a..92771bc1791f 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -594,6 +594,16 @@ do { \ this_cpu_read(hardirqs_enabled))); \ } while (0) +/* + * Acceptable for protecting per-CPU resources accessed from BH. + * Much like in_softirq() - semantics are ambiguous, use carefully. + */ +#define lockdep_assert_in_softirq() \ +do { \ + WARN_ON_ONCE(__lockdep_enabled && \ + (!in_softirq() || in_irq() || in_nmi())); \ +} while (0) + #else # define might_lock(lock) do { } while (0) # define might_lock_read(lock) do { } while (0) @@ -605,6 +615,7 @@ do { \ # define lockdep_assert_preemption_enabled() do { } while (0) # define lockdep_assert_preemption_disabled() do { } while (0) +# define lockdep_assert_in_softirq() do { } while (0) #endif #ifdef CONFIG_PROVE_RAW_LOCK_NESTING -- cgit v1.2.3