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| author | Yunsheng Lin <linyunsheng@huawei.com> | 2020-11-24 18:49:28 +0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2020-11-25 15:08:34 -0800 |
| commit | 8b5536ad1216c47fb9b37ef2cd0cfa70d79d4645 (patch) | |
| tree | 501780f646449de753cb071f3b6bc6908961a5b4 /include/linux/lockdep.h | |
| parent | b5094a3b535b5a258ab49ed9614948df63bc3557 (diff) | |
| download | lwn-8b5536ad1216c47fb9b37ef2cd0cfa70d79d4645.tar.gz lwn-8b5536ad1216c47fb9b37ef2cd0cfa70d79d4645.zip | |
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 <kuba@kernel.org>
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include/linux/lockdep.h')
| -rw-r--r-- | include/linux/lockdep.h | 11 |
1 files changed, 11 insertions, 0 deletions
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 |