Patchwork IB/ehca: Fix lockdep failures for shca_list_lock

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Submitter Joachim Fenkes
Date Nov. 21, 2008, 3:37 p.m.
Message ID <200811211637.15300.fenkes@de.ibm.com>
Download mbox | patch
Permalink /patch/10022/
State Not Applicable
Headers show

Comments

Joachim Fenkes - Nov. 21, 2008, 3:37 p.m.
From: Michael Ellerman <michael@ellerman.id.au>

shca_list_lock is taken from softirq context in ehca_poll_eqs, so we need to
lock IRQ safe elsewhere.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Joachim Fenkes <fenkes@de.ibm.com>
---
 drivers/infiniband/hw/ehca/ehca_main.c |   17 ++++++++++-------
 1 files changed, 10 insertions(+), 7 deletions(-)
Johannes Berg - Nov. 21, 2008, 4:02 p.m.
On Fri, 2008-11-21 at 16:37 +0100, Joachim Fenkes wrote:

> +	u64 flags;

> -	spin_lock(&shca_list_lock);
> +	spin_lock_irqsave(&shca_list_lock, flags);

That's wrong and I think will give a warning on all machines where
u64 != unsigned long. Might not particularly matter in this case.

Also, generally it seems wrong to say "fix lockdep failure" when the
patch really fixes a bug that lockdep happened to find.

johannes
Michael Ellerman - Nov. 22, 2008, 3:41 a.m.
On Fri, 2008-11-21 at 17:02 +0100, Johannes Berg wrote:
> On Fri, 2008-11-21 at 16:37 +0100, Joachim Fenkes wrote:
> 
> > +	u64 flags;
> 
> > -	spin_lock(&shca_list_lock);
> > +	spin_lock_irqsave(&shca_list_lock, flags);
> 
> That's wrong and I think will give a warning on all machines where
> u64 != unsigned long. Might not particularly matter in this case.

Crud, sorry.

> Also, generally it seems wrong to say "fix lockdep failure" when the
> patch really fixes a bug that lockdep happened to find.

True. I guess it should be "fix locking error found with lockdep", to
make it clear no one has actually hit the bug.

cheers

Patch

diff --git a/drivers/infiniband/hw/ehca/ehca_main.c b/drivers/infiniband/hw/ehca/ehca_main.c
index bb02a86..021c454 100644
--- a/drivers/infiniband/hw/ehca/ehca_main.c
+++ b/drivers/infiniband/hw/ehca/ehca_main.c
@@ -717,6 +717,7 @@  static int __devinit ehca_probe(struct of_device *dev,
 	const u64 *handle;
 	struct ib_pd *ibpd;
 	int ret, i, eq_size;
+	u64 flags;
 
 	handle = of_get_property(dev->node, "ibm,hca-handle", NULL);
 	if (!handle) {
@@ -830,9 +831,9 @@  static int __devinit ehca_probe(struct of_device *dev,
 		ehca_err(&shca->ib_device,
 			 "Cannot create device attributes  ret=%d", ret);
 
-	spin_lock(&shca_list_lock);
+	spin_lock_irqsave(&shca_list_lock, flags);
 	list_add(&shca->shca_list, &shca_list);
-	spin_unlock(&shca_list_lock);
+	spin_unlock_irqrestore(&shca_list_lock, flags);
 
 	return 0;
 
@@ -878,6 +879,7 @@  probe1:
 static int __devexit ehca_remove(struct of_device *dev)
 {
 	struct ehca_shca *shca = dev->dev.driver_data;
+	u64 flags;
 	int ret;
 
 	sysfs_remove_group(&dev->dev.kobj, &ehca_dev_attr_grp);
@@ -915,9 +917,9 @@  static int __devexit ehca_remove(struct of_device *dev)
 
 	ib_dealloc_device(&shca->ib_device);
 
-	spin_lock(&shca_list_lock);
+	spin_lock_irqsave(&shca_list_lock, flags);
 	list_del(&shca->shca_list);
-	spin_unlock(&shca_list_lock);
+	spin_unlock_irqrestore(&shca_list_lock, flags);
 
 	return ret;
 }
@@ -975,6 +977,7 @@  static int ehca_mem_notifier(struct notifier_block *nb,
 			     unsigned long action, void *data)
 {
 	static unsigned long ehca_dmem_warn_time;
+	unsigned long flags;
 
 	switch (action) {
 	case MEM_CANCEL_OFFLINE:
@@ -985,12 +988,12 @@  static int ehca_mem_notifier(struct notifier_block *nb,
 	case MEM_GOING_ONLINE:
 	case MEM_GOING_OFFLINE:
 		/* only ok if no hca is attached to the lpar */
-		spin_lock(&shca_list_lock);
+		spin_lock_irqsave(&shca_list_lock, flags);
 		if (list_empty(&shca_list)) {
-			spin_unlock(&shca_list_lock);
+			spin_unlock_irqrestore(&shca_list_lock, flags);
 			return NOTIFY_OK;
 		} else {
-			spin_unlock(&shca_list_lock);
+			spin_unlock_irqrestore(&shca_list_lock, flags);
 			if (printk_timed_ratelimit(&ehca_dmem_warn_time,
 						   30 * 1000))
 				ehca_gen_err("DMEM operations are not allowed"