[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen/events: remove event handling recursion detection
On 04.11.19 15:35, Jan Beulich wrote: On 04.11.2019 14:58, Juergen Gross wrote:__xen_evtchn_do_upcall() contains guards against being called recursively. This mechanism was introduced in the early pvops times (kernel 2.6.26) when there were still Xen versions around not honoring disabled interrupts for sending events to pv guests. This was changed in Xen 3.0, which is much older than any Xen version supported by the kernel, so the recursion detection can be removed.Would you mind pointing out which exact change(s) this was(were)? Linux kernel: 229664bee6126e01f8662976a5fe2e79813b77c8 Xen: d8263e8dbaf5ef1445bee0662143a0fcb6d43466 It had always been my understanding that the recursion detection was mainly to guard against drivers re-enabling interrupts transiently in their handlers (which in turn may no longer be an issue in modern Linux kernels). This would have been doable with a simple bool. The more complex xchg based logic was IMO for recursion detection at any point. Juergen _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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