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hyperv: Use mb() instead of atomic_thread_fence_seq_cst()

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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
This commit is contained in:
Sepherosa Ziehau 2016-04-07 05:31:22 +00:00
parent ae34b6ff96
commit d8258c4498
1 changed files with 10 additions and 2 deletions
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12
sys/dev/hyperv/vmbus/hv_vmbus_drv_freebsd.c
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@ -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) {
/*