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From: "Gustavo A. R. Silva" <>
To: "Paolo Bonzini" <>,
	"Radim Krčmář" <>
	"Gustavo A. R. Silva" <>
Subject: [PATCH] KVM: irqchip: Use struct_size() in kzalloc()
Date: Fri, 31 May 2019 14:24:53 -0500	[thread overview]
Message-ID: <20190531192453.GA13536@embeddedor> (raw)

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct foo {
   int stuff;
   struct boo entry[];

instance = kzalloc(sizeof(struct foo) + count * sizeof(struct boo), GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <>
 virt/kvm/irqchip.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/virt/kvm/irqchip.c b/virt/kvm/irqchip.c
index 79e59e4fa3dc..f8be6a3d1aa6 100644
--- a/virt/kvm/irqchip.c
+++ b/virt/kvm/irqchip.c
@@ -196,9 +196,7 @@ int kvm_set_irq_routing(struct kvm *kvm,
 	nr_rt_entries += 1;
-	new = kzalloc(sizeof(*new) + (nr_rt_entries * sizeof(struct hlist_head)),
+	new = kzalloc(struct_size(new, map, nr_rt_entries), GFP_KERNEL_ACCOUNT);
 	if (!new)
 		return -ENOMEM;

             reply	other threads:[~2019-05-31 19:25 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-31 19:24 Gustavo A. R. Silva [this message]
2019-06-04 17:20 ` Paolo Bonzini
2019-06-04 17:40   ` Gustavo A. R. Silva

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