[Lguest] [PATCH 05/16] make write() operation smp aware

[Glauber de Oliveira Costa]

This patch makes the write() file operation smp aware. Which means, receiving
the vcpu_id value through the offset parameter, and being well aware to which
vcpu we're talking to.

Signed-off-by: Glauber de Oliveira Costa <gcosta at redhat.com>
---
 drivers/lguest/lguest_user.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 216514b..d176004 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -230,14 +230,21 @@ static ssize_t write(struct file *file, const char __user *in,
 	struct lguest *lg = file->private_data;
 	const unsigned long __user *input = (const unsigned long __user *)in;
 	unsigned long req;
+	struct lg_vcpu *vcpu = NULL;
+	int vcpu_id = *off;
 
 	if (get_user(req, input) != 0)
 		return -EFAULT;
 	input++;
 
 	/* If you haven't initialized, you must do that first. */
-	if (req != LHREQ_INITIALIZE && !lg)
-		return -EINVAL;
+	if (req != LHREQ_INITIALIZE) {
+		if (!lg || (vcpu_id > lg->nr_vcpus))
+			return -EINVAL;
+		vcpu = &lg->vcpus[vcpu_id];
+		if (!vcpu)
+			return -EINVAL;
+	}
 
 	/* Once the Guest is dead, all you can do is read() why it died. */
 	if (lg && lg->dead)
-- 
1.5.0.6