3.16.62-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Dexuan Cui <[email protected]> commit 41e270f6898e7502be9fd6920ee0a108ca259d36 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 <[email protected]> Cc: K. Y. Srinivasan <[email protected]> Cc: Haiyang Zhang <[email protected]> Cc: Stephen Hemminger <[email protected]> Signed-off-by: K. Y. Srinivasan <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> [bwh: Backported to 3.16: - smp_processor_id() is only used once here - Adjust context] Signed-off-by: Ben Hutchings <[email protected]> --- drivers/hv/connection.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) --- a/drivers/hv/connection.c +++ b/drivers/hv/connection.c @@ -68,6 +68,7 @@ static int vmbus_negotiate_version(struc __u32 version) { int ret = 0; + unsigned int cur_cpu; struct vmbus_channel_initiate_contact *msg; unsigned long flags; @@ -80,8 +81,11 @@ static int vmbus_negotiate_version(struc msg->interrupt_page = virt_to_phys(vmbus_connection.int_page); msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]); msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]); - if (version == VERSION_WIN8_1) - msg->target_vcpu = hv_context.vp_index[smp_processor_id()]; + if (version == VERSION_WIN8_1) { + cur_cpu = get_cpu(); + msg->target_vcpu = hv_context.vp_index[cur_cpu]; + put_cpu(); + } /* * Add to list before we send the request since we may
