From 41e270f6898e7502be9fd6920ee0a108ca259d36 Mon Sep 17 00:00:00 2001 From: Dexuan Cui Date: Mon, 17 Sep 2018 04:14:54 +0000 Subject: [PATCH] Drivers: hv: vmbus: Use get/put_cpu() in vmbus_connect() 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 Cc: stable@vger.kernel.org Cc: K. Y. Srinivasan Cc: Haiyang Zhang Cc: Stephen Hemminger Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman --- drivers/hv/connection.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c index ced041899456..f4d08c8ac7f8 100644 --- a/drivers/hv/connection.c +++ b/drivers/hv/connection.c @@ -76,6 +76,7 @@ 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; @@ -118,9 +119,10 @@ 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;