Module Name: src Committed By: riastradh Date: Wed Aug 9 08:38:47 UTC 2023
Modified Files: src/sys/arch/xen/xen: xennetback_xenbus.c Log Message: xvif(4): Omit needless membars in xennetback_rx_copy_process. - No need for barrier around touching req_cons and rsp_prod_pvt, which are private. - RING_PUSH_RESPONSES_AND_CHECK_NOTIFY updates the shared req_prod and then issues xen_mb, which is all that we need between the update of shared req_prod and hypervisor_notify_via_evtchn. (Between updating the shared req_prod and issuing hypervisor_notify_via_evtchn, only xen_wmb is needed. But after writing to the shared req_prod, RING_PUSH_REQUESTS_AND_CHECK_NOTIFY must also read from the shared rsp_event, which requires the store-before-load ordering that only xen_mb provides.) To generate a diff of this commit: cvs rdiff -u -r1.121 -r1.122 src/sys/arch/xen/xen/xennetback_xenbus.c Please note that diffs are not public domain; they are subject to the copyright notices on the relevant files.
Modified files: Index: src/sys/arch/xen/xen/xennetback_xenbus.c diff -u src/sys/arch/xen/xen/xennetback_xenbus.c:1.121 src/sys/arch/xen/xen/xennetback_xenbus.c:1.122 --- src/sys/arch/xen/xen/xennetback_xenbus.c:1.121 Wed Aug 9 08:38:37 2023 +++ src/sys/arch/xen/xen/xennetback_xenbus.c Wed Aug 9 08:38:47 2023 @@ -1,4 +1,4 @@ -/* $NetBSD: xennetback_xenbus.c,v 1.121 2023/08/09 08:38:37 riastradh Exp $ */ +/* $NetBSD: xennetback_xenbus.c,v 1.122 2023/08/09 08:38:47 riastradh Exp $ */ /* * Copyright (c) 2006 Manuel Bouyer. @@ -25,7 +25,7 @@ */ #include <sys/cdefs.h> -__KERNEL_RCSID(0, "$NetBSD: xennetback_xenbus.c,v 1.121 2023/08/09 08:38:37 riastradh Exp $"); +__KERNEL_RCSID(0, "$NetBSD: xennetback_xenbus.c,v 1.122 2023/08/09 08:38:47 riastradh Exp $"); #include <sys/types.h> #include <sys/param.h> @@ -1024,14 +1024,12 @@ xennetback_rx_copy_process(struct ifnet } /* update pointer */ - xen_rmb(); xneti->xni_rxring.req_cons += queued; xneti->xni_rxring.rsp_prod_pvt += queued; RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&xneti->xni_rxring, notify); /* send event */ if (notify) { - xen_rmb(); XENPRINTF(("%s receive event\n", xneti->xni_if.if_xname)); hypervisor_notify_via_evtchn(xneti->xni_evtchn);