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hyperv: Use atomic_fetchadd_int to get GPADL id.

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Reviewed by:	Hongjiang Zhang <honzhan microsoft com>
MFC after:	1 week
Sponsored by:	Microsoft OSTC
Differential Revision:	https://reviews.freebsd.org/D5439
This commit is contained in:
Sepherosa Ziehau 2016-02-26 02:26:19 +00:00
parent caf1fb322e
commit 9021e53b29
1 changed files with 12 additions and 7 deletions
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19
sys/dev/hyperv/vmbus/hv_channel.c
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@ -384,17 +384,22 @@ hv_vmbus_channel_establish_gpadl(
hv_vmbus_channel_msg_info* curr;
uint32_t next_gpadl_handle;
next_gpadl_handle = hv_vmbus_g_connection.next_gpadl_handle;
atomic_add_int((int*) &hv_vmbus_g_connection.next_gpadl_handle, 1);
next_gpadl_handle = atomic_fetchadd_int(
&hv_vmbus_g_connection.next_gpadl_handle, 1);
ret = vmbus_channel_create_gpadl_header(
contig_buffer, size, &msg_info, &msg_count);
if(ret != 0) { /* if(allocation failed) return immediately */
/* reverse atomic_add_int above */
atomic_subtract_int((int*)
&hv_vmbus_g_connection.next_gpadl_handle, 1);
return ret;
if(ret != 0) {
/*
* XXX
* We can _not_ even revert the above incremental,
* if multiple GPADL establishments are running
* parallelly, decrement the global next_gpadl_handle
* is calling for _big_ trouble. A better solution
* is to have a 0-based GPADL id bitmap ...
*/
return ret;
}
sema_init(&msg_info->wait_sema, 0, "Open Info Sema");