On Tue, Feb 28, 2012 at 4:53 PM, Kyungmin Park
[off-list ref] wrote:

quoted

+void exynos_sysmmu_set_prefbuf(struct device *owner,
+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? unsigned long base0, unsigned long size0,
+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? unsigned long base1, unsigned long size1)
+{
+ ? ? struct sysmmu_drvdata *data = dev_get_drvdata(owner->archdata.iommu);
+ ? ? unsigned long flags;
+ ? ? int i;
+
+ ? ? BUG_ON((base0 + (size0 - 1)) <= base0);
+ ? ? BUG_ON((base1 + (size1 - 1)) <= base1);

Do you want to check size? BUG_ON(size <= 1);?

My mistake. :)
Thank you.

quoted

+
+ ? ? read_lock_irqsave(&data->lock, flags);
+ ? ? if (!is_sysmmu_active(data))
+ ? ? ? ? ? ? goto finish;
+
+ ? ? for (i = 0; i < data->nsfrs; i++) {
+ ? ? ? ? ? ? if ((readl(data->sfrbases[i] + S5P_MMU_VERSION) >> 28) == 3) {
+ ? ? ? ? ? ? ? ? ? ? sysmmu_block(data->sfrbases[i]);
+
+ ? ? ? ? ? ? ? ? ? ? if (size1 == 0) {

Is it possible? if size1 is '0', it can't pass the BUG_ON condition.

Although the above BUG_ON condition is incorrect, it can pass if size1
and base1 are 0
because the type of them is unsigned.

quoted

+
+ ? ? for (i = 0; i < data->nsfrs; i++) {
+ ? ? ? ? ? ? __sysmmu_set_ptbase(data->sfrbases[i], pgtable);
+
+ ? ? ? ? ? ? if ((readl(data->sfrbases[i] + S5P_MMU_VERSION) >> 28) == 3) {
+ ? ? ? ? ? ? ? ? ? ? /* System MMU version is 3.x */
+ ? ? ? ? ? ? ? ? ? ? __raw_writel((1 << 12) | (2 << 28),

Can you use the DEFINE instead of hard-code?

Do you think it is required even though it is used nowhere else here?

quoted

+static int exynos_iommu_attach_device(struct iommu_domain *domain,
+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct device *dev)
+{
+ ? ? int ret;
+ ? ? struct exynos_iommu_domain *priv = domain->priv;
+ ? ? struct iommu_client *client = NULL;
+ ? ? struct list_head *pos;
+ ? ? unsigned long flags;
+
+ ? ? spin_lock_irqsave(&priv->lock, flags);
+
+ ? ? list_for_each(pos, &priv->clients) {

Simply list_for_each_entry.

Variable 'client' must not be used as a loop cursor
because its value must not be changed unless a condition meets.

quoted

+ ? ? ? ? ? ? struct iommu_client *cur;
+
+ ? ? ? ? ? ? cur = list_entry(pos, struct iommu_client, node);
+ ? ? ? ? ? ? if (cur->dev == dev) {
+ ? ? ? ? ? ? ? ? ? ? client = cur;
+ ? ? ? ? ? ? ? ? ? ? break;
+ ? ? ? ? ? ? }
+ ? ? }
+
+ ? ? if (client != NULL) {
+ ? ? ? ? ? ? dev_dbg(dev, "%s: IOMMU with pgtable 0x%lx already attached\n",
+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? __func__, __pa(priv->pgtable));
+ ? ? ? ? ? ? client->refcnt++;
+ ? ? }
+
+ ? ? spin_unlock_irqrestore(&priv->lock, flags);
+
+ ? ? if (client != NULL)
+ ? ? ? ? ? ? return 0;
+
+ ? ? client = kmalloc(sizeof(*client), GFP_KERNEL);

Maybe attach called frequently. how about to use kmem_cache-*?

Thank you for advice.

quoted

+ ? ? if (!client)
+ ? ? ? ? ? ? return -ENOMEM;
+
+ ? ? INIT_LIST_HEAD(&client->node);
+ ? ? client->dev = dev;
+ ? ? client->refcnt = 1;

Dose it possible attach more than one? OMAP has multiple attach codes.

Yes. This function returns earlier than this if client->refcnt is larger than 1.
Please check "if (client != NULL) return 0;" statement in this function.

quoted

+ ? ? ret = __exynos_sysmmu_enable(dev, __pa(priv->pgtable), domain);
+ ? ? if (ret) {
+ ? ? ? ? ? ? kfree(client);
+ ? ? ? ? ? ? return ret;
+ ? ? }
+
+ ? ? spin_lock_irqsave(&priv->lock, flags);
+ ? ? list_add_tail(&client->node, &priv->clients);
+ ? ? spin_unlock_irqrestore(&priv->lock, flags);
+
+ ? ? dev_dbg(dev, "%s: Attached new IOMMU with pgtable 0x%lx\n", __func__,
+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? __pa(priv->pgtable));
+ ? ? return 0;
+}
+
+static void exynos_iommu_detach_device(struct iommu_domain *domain,
+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? struct device *dev)
+{
+ ? ? struct exynos_iommu_domain *priv = domain->priv;
+ ? ? struct iommu_client *client = NULL;
+ ? ? struct list_head *pos;
+ ? ? unsigned long flags;
+
+ ? ? spin_lock_irqsave(&priv->lock, flags);
+
+ ? ? list_for_each(pos, &priv->clients) {
+ ? ? ? ? ? ? struct iommu_client *cur;
+
+ ? ? ? ? ? ? cur = list_entry(pos, struct iommu_client, node);
+ ? ? ? ? ? ? if (cur->dev == dev) {
+ ? ? ? ? ? ? ? ? ? ? cur->refcnt--;
+ ? ? ? ? ? ? ? ? ? ? client = cur;
+ ? ? ? ? ? ? ? ? ? ? break;
+ ? ? ? ? ? ? }
+ ? ? }
+
+ ? ? spin_unlock_irqrestore(&priv->lock, flags);
+
+ ? ? if (WARN_ON(client == NULL))
+ ? ? ? ? ? ? return;
+
+ ? ? if (client->refcnt > 0) {

It never triggered. as you use true/false scheme. I remember you said
previous patch. use the refcount but actual meaning is true/false.

I think you are talking about the conversations about v6 patchset.
client->refcnt is really a reference counter.

quoted

+ ? ? ? ? ? ? dev_dbg(dev, "%s: Detaching IOMMU with pgtable 0x%lx delayed\n",
+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? __func__, __pa(priv->pgtable));
+ ? ? ? ? ? ? return;
+ ? ? }
+
+ ? ? BUG_ON(client->refcnt != 0);

Do you think "minus value"?

Yes. but I think it never be happened logically.
It is just "assert(client->refcnt == 0)".
May it is better to remove the BUG_ON.


Thank you for kind review.

Cho KyongHo.