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Drivers: hv: vmbus: Use get/put_cpu() in vmbus_connect() 

commit 41e270f689 upstream.

With CONFIG_DEBUG_PREEMPT=y, I always see this warning:
BUG: using smp_processor_id() in preemptible [00000000]

Fix the false warning by using get/put_cpu().

Here vmbus_connect() sends a message to the host and waits for the
host's response. The host will deliver the response message and an
interrupt on CPU msg->target_vcpu, and later the interrupt handler
will wake up vmbus_connect(). vmbus_connect() doesn't really have
to run on the same cpu as CPU msg->target_vcpu, so it's safe to
call put_cpu() just here.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Cc: stable@vger.kernel.org
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
Dexuan Cui 2018-09-17 04:14:54 +00:00 committed by Greg Kroah-Hartman
parent 119bf9470b
commit 1d24e26090
1 changed files with 5 additions and 3 deletions
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8
drivers/hv/connection.c
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@ -74,6 +74,7 @@ static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
__u32 version)
{
int ret = 0;
unsigned int cur_cpu;
struct vmbus_channel_initiate_contact *msg;
unsigned long flags;
@ -96,9 +97,10 @@ static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
* the CPU attempting to connect may not be CPU 0.
*/
if (version >= VERSION_WIN8_1) {
msg->target_vcpu =
hv_cpu_number_to_vp_number(smp_processor_id());
vmbus_connection.connect_cpu = smp_processor_id();
cur_cpu = get_cpu();
msg->target_vcpu = hv_cpu_number_to_vp_number(cur_cpu);
vmbus_connection.connect_cpu = cur_cpu;
put_cpu();
} else {
msg->target_vcpu = 0;
vmbus_connection.connect_cpu = 0;