Messages in this thread | | | Subject | Re: [PATCH net-next] net: add in_softirq() debug checking in napi_consume_skb() | From | Yunsheng Lin <> | Date | Thu, 19 Nov 2020 17:19:44 +0800 |
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On 2020/11/19 0:26, Jakub Kicinski wrote: > On Wed, 18 Nov 2020 16:57:57 +0100 Peter Zijlstra wrote: >> On Wed, Nov 18, 2020 at 07:43:48AM -0800, Jakub Kicinski wrote: >> >>> TBH the last sentence I wrote isn't clear even to me at this point ;D >>> >>> Maybe using just the macros from preempt.h - like this? >>> >>> #define lockdep_assert_in_softirq() \ >>> do { \ >>> WARN_ON_ONCE(__lockdep_enabled && \ >>> (!in_softirq() || in_irq() || in_nmi()) \ >>> } while (0)
One thing I am not so sure about is the different irq context indicator in preempt.h and lockdep.h, for example lockdep_assert_in_irq() uses this_cpu_read(hardirq_context) in lockdep.h, and in_irq() uses current_thread_info()->preempt_count in preempt.h, if they are the same thing?
>>> >>> We know what we're doing so in_softirq() should be fine (famous last >>> words). >> >> So that's not actually using any lockdep state. But if that's what you >> need, I don't have any real complaints. > > Great, thanks! > > The motivation was to piggy back on lockdep rather than adding a > one-off Kconfig knob for a check in the fast path in networking. > . >
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