linux-kernel - [PATCH 3/5] random: add interrupt callback to VMBus IRQ handler

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Date:	Mon, 30 May 2016 01:39:23 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Linux Kernel Developers List <linux-kernel@...r.kernel.org>
Cc:	smueller@...onox.de, herbert@...dor.apana.org.au,
	andi@...stfloor.org, sandyinchina@...il.com,
	cryptography@...edaemon.net, jsd@...n.com, hpa@...or.com,
	linux-crypto@...r.kernel.org,
	Stephan Mueller <stephan.mueller@...ec.com>,
	Theodore Ts'o <tytso@....edu>
Subject: [PATCH 3/5] random: add interrupt callback to VMBus IRQ handler

From: Stephan Mueller <smueller@...onox.de>

The Hyper-V Linux Integration Services use the VMBus implementation for
communication with the Hypervisor. VMBus registers its own interrupt
handler that completely bypasses the common Linux interrupt handling.
This implies that the interrupt entropy collector is not triggered.

This patch adds the interrupt entropy collection callback into the VMBus
interrupt handler function.

Signed-off-by: Stephan Mueller <stephan.mueller@...ec.com>
Signed-off-by: Stephan Mueller <smueller@...onox.de>
Signed-off-by: Theodore Ts'o <tytso@....edu>
---
 drivers/char/random.c  | 1 +
 drivers/hv/vmbus_drv.c | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 1778c84..bf370a3 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1141,6 +1141,7 @@ void add_interrupt_randomness(int irq, int irq_flags)
 	/* award one bit for the contents of the fast pool */
 	credit_entropy_bits(r, credit + 1);
 }
+EXPORT_SYMBOL_GPL(add_interrupt_randomness);
 
 #ifdef CONFIG_BLOCK
 void add_disk_randomness(struct gendisk *disk)
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 952f20f..e82f7e1 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -42,6 +42,7 @@
 #include <linux/screen_info.h>
 #include <linux/kdebug.h>
 #include <linux/efi.h>
+#include <linux/random.h>
 #include "hyperv_vmbus.h"
 
 static struct acpi_device  *hv_acpi_dev;
@@ -806,6 +807,8 @@ static void vmbus_isr(void)
 		else
 			tasklet_schedule(hv_context.msg_dpc[cpu]);
 	}
+
+	add_interrupt_randomness(HYPERVISOR_CALLBACK_VECTOR, 0);
 }
 
 
-- 
2.5.0