svn commit: r296076 - head/sys/dev/hyperv/vmbus
Sepherosa Ziehau
sephe at FreeBSD.org
Fri Feb 26 02:26:21 UTC 2016
Author: sephe
Date: Fri Feb 26 02:26:19 2016
New Revision: 296076
URL: https://svnweb.freebsd.org/changeset/base/296076
Log:
hyperv: Use atomic_fetchadd_int to get GPADL id.
Reviewed by: Hongjiang Zhang <honzhan microsoft com>
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D5439
Modified:
head/sys/dev/hyperv/vmbus/hv_channel.c
Modified: head/sys/dev/hyperv/vmbus/hv_channel.c
==============================================================================
--- head/sys/dev/hyperv/vmbus/hv_channel.c Fri Feb 26 01:52:33 2016 (r296075)
+++ head/sys/dev/hyperv/vmbus/hv_channel.c Fri Feb 26 02:26:19 2016 (r296076)
@@ -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");
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