[PATCH] xen/mce: schedule a workqueue to avoid sleep in atomic con=

[Liu , Jinsong]

copy_to_user might sleep and print a stack trace if it is executed
in an atomic spinlock context.

This patch schedule a workqueue for IRQ handler to poll the data,
and use mutex instead of spinlock, so copy_to_user sleep in atomic
context would not occur.

Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Suggested-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
---
 drivers/xen/mcelog.c |   18 +++++++++++-------
 1 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/xen/mcelog.c b/drivers/xen/mcelog.c
index 72e87d2..804aa3c 100644
--- a/drivers/xen/mcelog.c
+++ b/drivers/xen/mcelog.c
@@ -55,7 +55,7 @@ static struct mc_info g_mi;
 static struct mcinfo_logical_cpu *g_physinfo;
 static uint32_t ncpus;
=20
-static DEFINE_SPINLOCK(mcelog_lock);
+static DEFINE_MUTEX(mcelog_lock);
=20
 static struct xen_mce_log xen_mcelog =3D {
 	.signature	=3D XEN_MCE_LOG_SIGNATURE,
@@ -106,7 +106,7 @@ static ssize_t xen_mce_chrdev_read(struct file *filp, c=
har __user *ubuf,
 	unsigned num;
 	int i, err;
=20
-	spin_lock(&mcelog_lock);
+	mutex_lock(&mcelog_lock);
=20
 	num =3D xen_mcelog.next;
=20
@@ -130,7 +130,7 @@ static ssize_t xen_mce_chrdev_read(struct file *filp, c=
har __user *ubuf,
 		err =3D -EFAULT;
=20
 out:
-	spin_unlock(&mcelog_lock);
+	mutex_unlock(&mcelog_lock);
=20
 	return err ? err : buf - ubuf;
 }
@@ -310,12 +310,11 @@ static int mc_queue_handle(uint32_t flags)
 }
=20
 /* virq handler for machine check error info*/
-static irqreturn_t xen_mce_interrupt(int irq, void *dev_id)
+static void xen_mce_work_fn(struct work_struct *work)
 {
 	int err;
-	unsigned long tmp;
=20
-	spin_lock_irqsave(&mcelog_lock, tmp);
+	mutex_lock(&mcelog_lock);
=20
 	/* urgent mc_info */
 	err =3D mc_queue_handle(XEN_MC_URGENT);
@@ -330,8 +329,13 @@ static irqreturn_t xen_mce_interrupt(int irq, void *de=
v_id)
 		pr_err(XEN_MCELOG
 		       "Failed to handle nonurgent mc_info queue.\n");
=20
-	spin_unlock_irqrestore(&mcelog_lock, tmp);
+	mutex_unlock(&mcelog_lock);
+}
+static DECLARE_WORK(xen_mce_work, xen_mce_work_fn);
=20
+static irqreturn_t xen_mce_interrupt(int irq, void *dev_id)
+{
+	schedule_work(&xen_mce_work);
 	return IRQ_HANDLED;
 }
=20
--=20
1.7.1

--_002_DE8DF0795D48FD4CA783C40EC8292335228748SHSMSX101ccrcorpi_
Content-Type: application/octet-stream;
	name="0001-xen-mce-schedule-a-workqueue-to-avoid-sleep-in-atomi.patch"
Content-Description: 0001-xen-mce-schedule-a-workqueue-to-avoid-sleep-in-atomi.patch
Content-Disposition: attachment;
	filename="0001-xen-mce-schedule-a-workqueue-to-avoid-sleep-in-atomi.patch";
	size=2441; creation-date="Tue, 12 Jun 2012 07:45:53 GMT";
	modification-date="Tue, 12 Jun 2012 15:39:38 GMT"
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--_002_DE8DF0795D48FD4CA783C40EC8292335228748SHSMSX101ccrcorpi_--
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