[PATCH 0/5] staging: gasket: fixes and cleanups

[PATCH 0/5] staging: gasket: fixes and cleanups

[Todd Poynor]

From: Todd Poynor <toddpoynor@google.com>

The fun continues with gasket+apex: remove dead code and unnecessary
stuff, fixup apex PCI class for devices that advertise class 0
(undefined), and make sure the struct device doesn't go away on us.
Most of these from review comments of previous patch series.

Todd Poynor (5):
  staging: gasket: sysfs: remove check for refcount already zero
  staging: gasket: apex: fixup undefined PCI class
  staging: gasket: sysfs: remove unnecessary NULL check on device ptr
  staging: gasket: page table: remove code for "no dma_ops"
  staging: gasket: core: hold reference on device kobj while in use

 drivers/staging/gasket/apex_driver.c       |  7 +++
 drivers/staging/gasket/gasket_core.c       |  5 +-
 drivers/staging/gasket/gasket_page_table.c | 58 +++-------------------
 drivers/staging/gasket/gasket_page_table.h |  3 +-
 drivers/staging/gasket/gasket_sysfs.c      |  7 ---
 5 files changed, 17 insertions(+), 63 deletions(-)

-- 
2.18.0.345.g5c9ce644c3-goog

[PATCH 1/5] staging: gasket: sysfs: remove check for refcount already zero

[Todd Poynor]

From: Todd Poynor <toddpoynor@google.com>

Remove the check for refcount already zero, which shouldn't be
necessary.

Signed-off-by: Todd Poynor <toddpoynor@google.com>
---
 drivers/staging/gasket/gasket_sysfs.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/staging/gasket/gasket_sysfs.c b/drivers/staging/gasket/gasket_sysfs.c
index 418b81797e638..2d8647de697cd 100644
--- a/drivers/staging/gasket/gasket_sysfs.c
+++ b/drivers/staging/gasket/gasket_sysfs.c
@@ -111,8 +111,6 @@ static void put_mapping(struct gasket_sysfs_mapping *mapping)
 	}
 
 	mutex_lock(&mapping->mutex);
-	if (refcount_read(&mapping->refcount.refcount) == 0)
-		dev_err(mapping->device, "Refcount is already 0\n");
 	if (kref_put(&mapping->refcount, release_entry)) {
 		dev_dbg(mapping->device, "Removing Gasket sysfs mapping\n");
 		/*
-- 
2.18.0.345.g5c9ce644c3-goog

[PATCH 2/5] staging: gasket: apex: fixup undefined PCI class

[Todd Poynor]

From: Todd Poynor <toddpoynor@google.com>

Apex chips with class 0 (PCI_CLASS_NOT_DEFINED) fixed up to
PCI_CLASS_SYSTEM_OTHER to enable PCI resource assignments.

Signed-off-by: Todd Poynor <toddpoynor@google.com>
---
 drivers/staging/gasket/apex_driver.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/staging/gasket/apex_driver.c b/drivers/staging/gasket/apex_driver.c
index 73fc2683a834d..ab466d49608a7 100644
--- a/drivers/staging/gasket/apex_driver.c
+++ b/drivers/staging/gasket/apex_driver.c
@@ -739,3 +739,10 @@ static ssize_t sysfs_show(
 	gasket_sysfs_put_device_data(device, gasket_dev);
 	return ret;
 }
+
+static void apex_pci_fixup_class(struct pci_dev *pdev)
+{
+	pdev->class = (PCI_CLASS_SYSTEM_OTHER << 8) | pdev->class;
+}
+DECLARE_PCI_FIXUP_CLASS_HEADER(APEX_PCI_VENDOR_ID, APEX_PCI_DEVICE_ID,
+			       PCI_CLASS_NOT_DEFINED, 8, apex_pci_fixup_class);
-- 
2.18.0.345.g5c9ce644c3-goog

[PATCH 3/5] staging: gasket: sysfs: remove unnecessary NULL check on device ptr

[Todd Poynor]

From: Todd Poynor <toddpoynor@google.com>

The device pointer passed into get_mapping() will never be NULL; the
check is unnecessary.

Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Todd Poynor <toddpoynor@google.com>
---
 drivers/staging/gasket/gasket_sysfs.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/staging/gasket/gasket_sysfs.c b/drivers/staging/gasket/gasket_sysfs.c
index 2d8647de697cd..da972ce0e0db0 100644
--- a/drivers/staging/gasket/gasket_sysfs.c
+++ b/drivers/staging/gasket/gasket_sysfs.c
@@ -67,11 +67,6 @@ static struct gasket_sysfs_mapping *get_mapping(struct device *device)
 {
 	int i;
 
-	if (!device) {
-		pr_debug("%s: Received NULL device\n", __func__);
-		return NULL;
-	}
-
 	for (i = 0; i < GASKET_SYSFS_NUM_MAPPINGS; i++) {
 		mutex_lock(&dev_mappings[i].mutex);
 		if (dev_mappings[i].device == device) {
-- 
2.18.0.345.g5c9ce644c3-goog

[PATCH 4/5] staging: gasket: page table: remove code for "no dma_ops"

[Todd Poynor]

From: Todd Poynor <toddpoynor@google.com>

Remove code with TODOs on it for working around apparent problems
previously seen in a qemu environment where dma_ops was not set
correctly.  There is no user of this in the current code.

Signed-off-by: Todd Poynor <toddpoynor@google.com>
---
 drivers/staging/gasket/gasket_core.c       |  2 +-
 drivers/staging/gasket/gasket_page_table.c | 58 +++-------------------
 drivers/staging/gasket/gasket_page_table.h |  3 +-
 3 files changed, 8 insertions(+), 55 deletions(-)

diff --git a/drivers/staging/gasket/gasket_core.c b/drivers/staging/gasket/gasket_core.c
index f44805c38159b..859a6df9e12df 100644
--- a/drivers/staging/gasket/gasket_core.c
+++ b/drivers/staging/gasket/gasket_core.c
@@ -916,7 +916,7 @@ static int gasket_enable_dev(
 			&gasket_dev->bar_data[
 				driver_desc->page_table_bar_index],
 			&driver_desc->page_table_configs[tbl_idx],
-			gasket_dev->dev, gasket_dev->pci_dev, true);
+			gasket_dev->dev, gasket_dev->pci_dev);
 		if (ret) {
 			dev_err(gasket_dev->dev,
 				"Couldn't init page table %d: %d\n",
diff --git a/drivers/staging/gasket/gasket_page_table.c b/drivers/staging/gasket/gasket_page_table.c
index 32f1c1e10c7e2..722839603f20d 100644
--- a/drivers/staging/gasket/gasket_page_table.c
+++ b/drivers/staging/gasket/gasket_page_table.c
@@ -212,12 +212,6 @@ struct gasket_page_table {
 	 * gasket_mmap function, so user_virt belongs in the driver anyhow.
 	 */
 	struct gasket_coherent_page_entry *coherent_pages;
-
-	/*
-	 * Whether the page table uses arch specific dma_ops or
-	 * whether the driver is supplying its own.
-	 */
-	bool dma_ops;
 };
 
 /* Mapping declarations */
@@ -290,7 +284,7 @@ int gasket_page_table_init(
 	struct gasket_page_table **ppg_tbl,
 	const struct gasket_bar_data *bar_data,
 	const struct gasket_page_table_config *page_table_config,
-	struct device *device, struct pci_dev *pci_dev, bool has_dma_ops)
+	struct device *device, struct pci_dev *pci_dev)
 {
 	ulong bytes;
 	struct gasket_page_table *pg_tbl;
@@ -353,7 +347,6 @@ int gasket_page_table_init(
 		bar_data->virt_base[page_table_config->extended_reg]);
 	pg_tbl->device = device;
 	pg_tbl->pci_dev = pci_dev;
-	pg_tbl->dma_ops = has_dma_ops;
 
 	dev_dbg(device, "Page table initialized successfully\n");
 
@@ -759,33 +752,6 @@ static int gasket_map_extended_pages(
 	return 0;
 }
 
-/*
- * TODO: dma_map_page() is not plugged properly when running under qemu. i.e.
- * dma_ops are not set properly, which causes the kernel to assert.
- *
- * This temporary hack allows the driver to work on qemu, but need to be fixed:
- * - either manually set the dma_ops for the architecture (which incidentally
- * can't be done in an out-of-tree module) - or get qemu to fill the device tree
- * properly so as linux plug the proper dma_ops or so as the driver can detect
- * that it is runnig on qemu
- */
-static inline dma_addr_t _no_op_dma_map_page(
-	struct device *dev, struct page *page, size_t offset, size_t size,
-	enum dma_data_direction dir)
-{
-	/*
-	 * struct dma_map_ops *ops = get_dma_ops(dev);
-	 * dma_addr_t addr;
-	 *
-	 * kmemcheck_mark_initialized(page_address(page) + offset, size);
-	 * BUG_ON(!valid_dma_direction(dir));
-	 * addr = ops->map_page(dev, page, offset, size, dir, NULL);
-	 * debug_dma_map_page(dev, page, offset, size, dir, addr, false);
-	 */
-
-	return page_to_phys(page);
-}
-
 /*
  * Get and map last level page table buffers.
  * @pg_tbl: Gasket page table pointer.
@@ -856,16 +822,9 @@ static int gasket_perform_mapping(
 			ptes[i].offset = offset;
 
 			/* Map the page into DMA space. */
-			if (pg_tbl->dma_ops) {
-				/* hook in to kernel map functions */
-				ptes[i].dma_addr = dma_map_page(pg_tbl->device,
-					page, 0, PAGE_SIZE, DMA_BIDIRECTIONAL);
-			} else {
-				ptes[i].dma_addr = _no_op_dma_map_page(
-					pg_tbl->device, page, 0, PAGE_SIZE,
-					DMA_BIDIRECTIONAL);
-			}
-
+			ptes[i].dma_addr =
+				dma_map_page(pg_tbl->device, page, 0, PAGE_SIZE,
+					     DMA_BIDIRECTIONAL);
 			dev_dbg(pg_tbl->device,
 				"%s i %d pte %p pfn %p -> mapped %llx\n",
 				__func__, i, &ptes[i],
@@ -1042,13 +1001,8 @@ static int gasket_alloc_extended_subtable(
 	}
 
 	/* Map the page into DMA space. */
-	if (pg_tbl->dma_ops) {
-		pte->dma_addr = dma_map_page(pg_tbl->device, pte->page, 0,
-			PAGE_SIZE, DMA_BIDIRECTIONAL);
-	} else {
-		pte->dma_addr = _no_op_dma_map_page(pg_tbl->device, pte->page,
-			0, PAGE_SIZE, DMA_BIDIRECTIONAL);
-	}
+	pte->dma_addr = dma_map_page(pg_tbl->device, pte->page, 0, PAGE_SIZE,
+				     DMA_BIDIRECTIONAL);
 	/* Wait until the page is mapped. */
 	mb();
 
diff --git a/drivers/staging/gasket/gasket_page_table.h b/drivers/staging/gasket/gasket_page_table.h
index 0e8afdb8c1139..765588649365f 100644
--- a/drivers/staging/gasket/gasket_page_table.h
+++ b/drivers/staging/gasket/gasket_page_table.h
@@ -37,7 +37,6 @@ struct gasket_page_table;
  *                 translation table.
  * @device: Device structure for the underlying device. Only used for logging.
  * @pci_dev: PCI system descriptor for the underlying device.
- * @bool has_dma_ops: Whether the page table uses arch specific dma_ops or
  * whether the driver will supply its own.
  *
  * Description: Allocates and initializes data to track address translation -
@@ -51,7 +50,7 @@ int gasket_page_table_init(
 	struct gasket_page_table **ppg_tbl,
 	const struct gasket_bar_data *bar_data,
 	const struct gasket_page_table_config *page_table_config,
-	struct device *device, struct pci_dev *pci_dev, bool dma_ops);
+	struct device *device, struct pci_dev *pci_dev);
 
 /*
  * Deallocate and cleanup page table data.
-- 
2.18.0.345.g5c9ce644c3-goog

[PATCH 5/5] staging: gasket: core: hold reference on device kobj while in use

[Todd Poynor]

From: Todd Poynor <toddpoynor@google.com>

Hold a reference on the struct device kobject while a pointer to that
device is in use by gasket.

Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Todd Poynor <toddpoynor@google.com>
---
 drivers/staging/gasket/gasket_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/gasket/gasket_core.c b/drivers/staging/gasket/gasket_core.c
index 859a6df9e12df..1dc7273e38734 100644
--- a/drivers/staging/gasket/gasket_core.c
+++ b/drivers/staging/gasket/gasket_core.c
@@ -449,6 +449,7 @@ static int gasket_alloc_dev(
 	gasket_dev->dev_idx = dev_idx;
 	snprintf(gasket_dev->kobj_name, GASKET_NAME_MAX, "%s", kobj_name);
 	gasket_dev->dev = parent;
+	kobject_get(&gasket_dev->dev->kobj);
 	/* gasket_bar_data is uninitialized. */
 	gasket_dev->num_page_tables = driver_desc->num_page_tables;
 	/* max_page_table_size and *page table are uninit'ed */
@@ -487,7 +488,7 @@ static void gasket_free_dev(struct gasket_dev *gasket_dev)
 	mutex_lock(&internal_desc->mutex);
 	internal_desc->devs[gasket_dev->dev_idx] = NULL;
 	mutex_unlock(&internal_desc->mutex);
-
+	kobject_put(&gasket_dev->dev->kobj);
 	kfree(gasket_dev);
 }
 
-- 
2.18.0.345.g5c9ce644c3-goog

Re: [PATCH 5/5] staging: gasket: core: hold reference on device kobj while in use

[Greg Kroah-Hartman]

On Fri, Jul 27, 2018 at 10:22:00PM -0700, Todd Poynor wrote:
> From: Todd Poynor <toddpoynor@google.com>
> 
> Hold a reference on the struct device kobject while a pointer to that
> device is in use by gasket.
> 
> Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Todd Poynor <toddpoynor@google.com>
> ---
>  drivers/staging/gasket/gasket_core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/gasket/gasket_core.c b/drivers/staging/gasket/gasket_core.c
> index 859a6df9e12df..1dc7273e38734 100644
> --- a/drivers/staging/gasket/gasket_core.c
> +++ b/drivers/staging/gasket/gasket_core.c
> @@ -449,6 +449,7 @@ static int gasket_alloc_dev(
>  	gasket_dev->dev_idx = dev_idx;
>  	snprintf(gasket_dev->kobj_name, GASKET_NAME_MAX, "%s", kobj_name);
>  	gasket_dev->dev = parent;
> +	kobject_get(&gasket_dev->dev->kobj);

Hint, if you are a driver, working with devices, you should never call a
kobject_* or sysfs_* call.  If you are, you are doing something really
wrong and odd and should seriously reconsider it.  No driver should ever
be touching a "raw" kobject.

For this case, get_device()/put_device() is what you should be using.

thanks,

greg k-h