Date: Thu, 7 Apr 2016 05:31:22 +0000 (UTC) From: Sepherosa Ziehau <sephe@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r297634 - head/sys/dev/hyperv/vmbus Message-ID: <201604070531.u375VMS9041113@repo.freebsd.org>
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Author: sephe Date: Thu Apr 7 05:31:22 2016 New Revision: 297634 URL: https://svnweb.freebsd.org/changeset/base/297634 Log: hyperv: Use mb() instead of atomic_thread_fence_seq_cst() Since atomic_thread_fence_seq_cst() will become compiler fence on UP kernel. Reviewed by: kib, Dexuan Cui <decui microsoft com> MFC after: 1 week Sponsored by: Microsoft OSTC Differential Revision: https://reviews.freebsd.org/D5852 Modified: head/sys/dev/hyperv/vmbus/hv_vmbus_drv_freebsd.c Modified: head/sys/dev/hyperv/vmbus/hv_vmbus_drv_freebsd.c ============================================================================== --- head/sys/dev/hyperv/vmbus/hv_vmbus_drv_freebsd.c Thu Apr 7 04:23:25 2016 (r297633) +++ head/sys/dev/hyperv/vmbus/hv_vmbus_drv_freebsd.c Thu Apr 7 05:31:22 2016 (r297634) @@ -117,8 +117,12 @@ handled: * message_pending and EOMing. Otherwise, the EOMing will * not deliver any more messages * since there is no empty slot + * + * NOTE: + * mb() is used here, since atomic_thread_fence_seq_cst() + * will become compler fence on UP kernel. */ - atomic_thread_fence_seq_cst(); + mb(); if (msg->header.message_flags.u.message_pending) { /* @@ -190,8 +194,12 @@ hv_vmbus_isr(struct trapframe *frame) * message_pending and EOMing. Otherwise, the EOMing will * not deliver any more messages * since there is no empty slot + * + * NOTE: + * mb() is used here, since atomic_thread_fence_seq_cst() + * will become compler fence on UP kernel. */ - atomic_thread_fence_seq_cst(); + mb(); if (msg->header.message_flags.u.message_pending) { /*
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