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Subject[PATCH 4/4] Drivers: hv: vmbus: Use cpumask_var_t for on-stack cpu mask
Date
From: Dexuan Cui <decui@microsoft.com>

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>
---
drivers/hv/channel_mgmt.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index e7598b569bea..d943fa022e34 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -601,16 +601,18 @@ 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;
@@ -648,7 +650,7 @@ 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;
@@ -666,10 +668,10 @@ 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;
}
@@ -699,6 +701,8 @@ 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)
--
2.18.0
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