Drivers: hv: vmbus: Use cpumask_var_t for on-stack cpu mask

[ Upstream commit 25355252607ca288f329ee033f387764883393f6 ]

A cpumask structure on the stack can cause a warning with
CONFIG_NR_CPUS=8192 (e.g. Ubuntu 16.04 and 18.04 use this):

drivers/hv//channel_mgmt.c: In function ‘init_vp_index’:
drivers/hv//channel_mgmt.c:702:1: warning: the frame size of 1032 bytes
  is larger than 1024 bytes [-Wframe-larger-than=]

Nowadays it looks most distros enable CONFIG_CPUMASK_OFFSTACK=y, and
hence we can work around the warning by using cpumask_var_t.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 1700b4e..752c52f 100644 (file)
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -599,16 +599,18 @@ static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
        bool perf_chn = vmbus_devs[dev_type].perf_device;
        struct vmbus_channel *primary = channel->primary_channel;
        int next_node;
-       struct cpumask available_mask;
+       cpumask_var_t available_mask;
        struct cpumask *alloced_mask;
 
        if ((vmbus_proto_version == VERSION_WS2008) ||
-           (vmbus_proto_version == VERSION_WIN7) || (!perf_chn)) {
+           (vmbus_proto_version == VERSION_WIN7) || (!perf_chn) ||
+           !alloc_cpumask_var(&available_mask, GFP_KERNEL)) {
                /*
                 * Prior to win8, all channel interrupts are
                 * delivered on cpu 0.
                 * Also if the channel is not a performance critical
                 * channel, bind it to cpu 0.
+                * In case alloc_cpumask_var() fails, bind it to cpu 0.
                 */
                channel->numa_node = 0;
                channel->target_cpu = 0;
@@ -646,7 +648,7 @@ static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
                cpumask_clear(alloced_mask);
        }
 
-       cpumask_xor(&available_mask, alloced_mask,
+       cpumask_xor(available_mask, alloced_mask,
                    cpumask_of_node(primary->numa_node));
 
        cur_cpu = -1;
@@ -664,10 +666,10 @@ static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
        }
 
        while (true) {
-               cur_cpu = cpumask_next(cur_cpu, &available_mask);
+               cur_cpu = cpumask_next(cur_cpu, available_mask);
                if (cur_cpu >= nr_cpu_ids) {
                        cur_cpu = -1;
-                       cpumask_copy(&available_mask,
+                       cpumask_copy(available_mask,
                                     cpumask_of_node(primary->numa_node));
                        continue;
                }
@@ -697,6 +699,8 @@ static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
 
        channel->target_cpu = cur_cpu;
        channel->target_vp = hv_cpu_number_to_vp_number(cur_cpu);
+
+       free_cpumask_var(available_mask);
 }
 
 static void vmbus_wait_for_unload(void)