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patch "Drivers: hv: vmbus: Use cpumask_var_t for on-stack cpu mask" added to char-misc-testing

PATCH [email protected] 1 participant 1 message Oct 2, 2018

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This is a note to let you know that I've just added the patch titled

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

to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-testing branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will be merged to the char-misc-next branch sometime soon, after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.

Quoted 1 line

From 25355252607ca288f329ee033f387764883393f6 Mon Sep 17 00:00:00 2001

From: Dexuan Cui <[email protected]>
Date: Sun, 23 Sep 2018 21:10:44 +0000
Subject: Drivers: hv: vmbus: Use cpumask_var_t for on-stack cpu mask
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

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 <[email protected]>
Cc K. Y. Srinivasan <[email protected]>
Cc Haiyang Zhang <[email protected]>
Cc Stephen Hemminger <[email protected]>
Cc <[email protected]>
Signed-off-by K. Y. Srinivasan <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/hv/channel_mgmt.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)
drivers/hv/channel_mgmt.c +9 -5
index 6f3e6af5e891..6277597d3d58 100644
@@ -594,16 +594,18 @@ 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;

@@ -641,7 +643,7 @@ 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;

@@ -659,10 +661,10 @@ 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;
 		}

@@ -692,6 +694,8 @@ 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)
Signature · 1 line
2.19.0