> -----Original Message-----
> From: Dexuan Cui
> Sent: Thursday, August 23, 2018 3:31 PM
> To: 'gre...@linuxfoundation.org' <gre...@linuxfoundation.org>; KY
> Srinivasan <k...@microsoft.com>; Stephen Hemminger
> <sthem...@microsoft.com>; Haiyang Zhang <haiya...@microsoft.com>
> Cc: 'linux-ker...@vger.kernel.org' <linux-ker...@vger.kernel.org>;
> 'driverdev-devel@linuxdriverproject.org' <driverdev-
> de...@linuxdriverproject.org>; 'o...@aepfle.de' <o...@aepfle.de>;
> 'a...@canonical.com' <a...@canonical.com>; 'jasow...@redhat.com'
> <jasow...@redhat.com>; vkuznets <vkuzn...@redhat.com>;
> 'marcelo.ce...@canonical.com' <marcelo.ce...@canonical.com>
> Subject: [PATCH] Drivers: hv: vmbus: Use raw_smp_processor_id() 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 raw_smp_processor_id().
>
> 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
> use raw_smp_processor_id() here.
>
> Signed-off-by: Dexuan Cui <de...@microsoft.com>
> Cc: sta...@vger.kernel.org
> Cc: K. Y. Srinivasan <k...@microsoft.com>
> Cc: Haiyang Zhang <haiya...@microsoft.com>
> Cc: Stephen Hemminger <sthem...@microsoft.com>
> ---
> drivers/hv/connection.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> index ced0418..c3b7040 100644
> --- a/drivers/hv/connection.c
> +++ b/drivers/hv/connection.c
> @@ -119,8 +119,8 @@ static int vmbus_negotiate_version(struct
> vmbus_channel_msginfo *msginfo,
> */
> if (version >= VERSION_WIN8_1) {
> msg->target_vcpu =
> -
> hv_cpu_number_to_vp_number(smp_processor_id());
> - vmbus_connection.connect_cpu = smp_processor_id();
> +
> hv_cpu_number_to_vp_number(raw_smp_processor_id());
> + vmbus_connection.connect_cpu = raw_smp_processor_id();
Dexuan,
We want a consistent view of the CPU we are currently running on. How about
doing something
like this:
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index ced041899456..4cc0877ba38a 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -119,8 +119,9 @@ static int vmbus_negotiate_version(struct
vmbus_channel_msginfo *msginfo,
*/
if (version >= VERSION_WIN8_1) {
msg->target_vcpu =
- hv_cpu_number_to_vp_number(smp_processor_id());
- vmbus_connection.connect_cpu = smp_processor_id();
+ hv_cpu_number_to_vp_number(get_cpu());
+ vmbus_connection.connect_cpu = msg->target_vcpu;
+ put_cpu();
} else {
msg->target_vcpu = 0;
vmbus_connection.connect_cpu = 0;
> } else {
> msg->target_vcpu = 0;
> vmbus_connection.connect_cpu = 0;
> --
> 2.7.4
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