[PATCH] MM: CMA: add a simple kernel module as the helper to test CMA

[PATCH] MM: CMA: add a simple kernel module as the helper to test CMA

[Barry Song]

From: Barry Song <Baohua.Song@csr.com>

Any write request to /dev/cma_test will let the module to allocate memory from
CMA, for example:

1st time
$ echo 0 > /dev/cma_test
will require cma_test to request 1MB
2nd time
$ echo 0 > /dev/cma_test
will require cma_test to request 2MB

Any read request to /dev/cma_test will let the module to free memory from CMA,
for example:

1st time
$ cat /dev/cma_test
will require cma_test to free the 1MB allocated in the first write request
2nd time
$ echo 0 > /dev/cma_test
will require cma_test to free the 2MB allocated in the second write request

Signed-off-by: Barry Song <Baohua.Song@csr.com>
---
 tools/cma/Makefile   |   13 ++++++
 tools/cma/cma_test.c |  108 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 121 insertions(+), 0 deletions(-)
 create mode 100644 tools/cma/Makefile
 create mode 100644 tools/cma/cma_test.c

diff --git a/tools/cma/Makefile b/tools/cma/Makefile
new file mode 100644
index 0000000..d15c2c0
--- /dev/null
+++ b/tools/cma/Makefile
@@ -0,0 +1,13 @@
+# Kernel modules
+#
+# To compile for ARM:
+# make ARCH=arm CC=arm-none-linux-gnueabi-gcc
+#
+obj-m	+= cma_test.o
+
+build: kernel_modules
+
+kernel_modules:
+	${MAKE} -C $(CURDIR)/../.. M=$(CURDIR)
+clean:
+	${MAKE} -C $(CURDIR)/../.. M=$(CURDIR) clean
diff --git a/tools/cma/cma_test.c b/tools/cma/cma_test.c
new file mode 100644
index 0000000..3ee89f3
--- /dev/null
+++ b/tools/cma/cma_test.c
@@ -0,0 +1,108 @@
+/*
+ * kernel module helper for testing CMA
+ *
+ * Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
+ *
+ * Licensed under GPLv2 or later.
+ */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/dma-mapping.h>
+
+#define CMA_NUM  10
+static struct device *cma_dev;
+static dma_addr_t dma_phys[CMA_NUM];
+static void *dma_virt[CMA_NUM];
+
+/* any read request will free coherent memory, eg.
+ * cat /dev/cma_test
+ */
+static ssize_t
+cma_test_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+	int i;
+
+	for (i = 0; i < CMA_NUM; i++) {
+		if (dma_virt[i]) {
+			dma_free_coherent(cma_dev, (i + 1) * SZ_1M, dma_virt[i], dma_phys[i]);
+			_dev_info(cma_dev, "free virt: %p phys: %p\n", dma_virt[i], (void *)dma_phys[i]);
+			dma_virt[i] = NULL;
+			break;
+		}
+	}
+	return 0;
+}
+
+/*
+ * any write request will alloc coherent memory, eg.
+ * echo 0 > /dev/cma_test
+ */
+static ssize_t
+cma_test_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+{
+	int i;
+	int ret;
+
+	for (i = 0; i < CMA_NUM; i++) {
+		if (!dma_virt[i]) {
+			dma_virt[i] = dma_alloc_coherent(cma_dev, (i + 1) * SZ_1M, &dma_phys[i], GFP_KERNEL);
+
+			if (dma_virt[i]) {
+				void *p;
+				/* touch every page in the allocated memory */
+				for (p = dma_virt[i]; p <  dma_virt[i] + (i + 1) * SZ_1M; p += PAGE_SIZE)
+					*(u32 *)p = 0;
+
+				_dev_info(cma_dev, "alloc virt: %p phys: %p\n", dma_virt[i], (void *)dma_phys[i]);
+			} else {
+				dev_err(cma_dev, "no mem in CMA area\n");
+				ret = -ENOMEM;
+			}
+			break;
+		}
+	}
+
+	return count;
+}
+
+static const struct file_operations cma_test_fops = {
+	.owner =    THIS_MODULE,
+	.read  =    cma_test_read,
+	.write =    cma_test_write,
+};
+
+static struct miscdevice cma_test_misc = {
+	.name = "cma_test",
+	.fops = &cma_test_fops,
+};
+
+static int __init cma_test_init(void)
+{
+	int ret = 0;
+
+	ret = misc_register(&cma_test_misc);
+	if (unlikely(ret)) {
+		pr_err("failed to register cma test misc device!\n");
+		return ret;
+	}
+	cma_dev = cma_test_misc.this_device;
+	cma_dev->coherent_dma_mask = ~0;
+	_dev_info(cma_dev, "registered.\n");
+
+	return ret;
+}
+module_init(cma_test_init);
+
+static void __exit cma_test_exit(void)
+{
+	misc_deregister(&cma_test_misc);
+}
+module_exit(cma_test_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Barry Song <Baohua.Song@csr.com>");
+MODULE_DESCRIPTION("kernel module to help the test of CMA");
+MODULE_ALIAS("CMA test");
-- 
1.7.1



Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom
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[PATCH] MM: CMA: add a simple kernel module as the helper to test CMA

[Michal Nazarewicz]

On Fri, 02 Mar 2012 03:52:22 +0100, Barry Song <Barry.Song@csr.com> wrote:

> From: Barry Song <Baohua.Song@csr.com>
>
> Any write request to /dev/cma_test will let the module to allocate memory from
> CMA, for example:
>
> 1st time
> $ echo 0 > /dev/cma_test
> will require cma_test to request 1MB
> 2nd time
> $ echo 0 > /dev/cma_test
> will require cma_test to request 2MB
>
> Any read request to /dev/cma_test will let the module to free memory from CMA,
> for example:
>
> 1st time
> $ cat /dev/cma_test
> will require cma_test to free the 1MB allocated in the first write request
> 2nd time
> $ echo 0 > /dev/cma_test
> will require cma_test to free the 2MB allocated in the second write request

Looks quite all right.  It has a race condition but I guess for a test device it's
not that big of a deal (I think the race cannot cause panic).  Either way, would be
nice if one could specify how much memory device should allocate.  How about those
changes:

diff --git a/tools/cma/cma_test.c b/tools/cma/cma_test.c
index 3ee89f3..3d3b074 100644
--- a/tools/cma/cma_test.c
+++ b/tools/cma/cma_test.c
@@ -6,66 +6,96 @@
   * Licensed under GPLv2 or later.
   */

-#include <linux/module.h>
  #include <linux/device.h>
+#include <linux/dma-mapping.h>
  #include <linux/fs.h>
+#include <linux/list.h>
  #include <linux/miscdevice.h>
-#include <linux/dma-mapping.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+
+struct cma_allocation {
+	struct list_head list;
+	unsigned long size;
+	dma_addr_t dma;
+	void *virt;
+};

-#define CMA_NUM  10
  static struct device *cma_dev;
-static dma_addr_t dma_phys[CMA_NUM];
-static void *dma_virt[CMA_NUM];
+static LIST_HEAD(cma_allocations);
+static DEFINE_SPINLOCK(cma_lock);

-/* any read request will free coherent memory, eg.
+/*
+ * Any read request will free a single coherent memory, eg.
   * cat /dev/cma_test
   */
  static ssize_t
  cma_test_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
  {
-	int i;
-
-	for (i = 0; i < CMA_NUM; i++) {
-		if (dma_virt[i]) {
-			dma_free_coherent(cma_dev, (i + 1) * SZ_1M, dma_virt[i], dma_phys[i]);
-			_dev_info(cma_dev, "free virt: %p phys: %p\n", dma_virt[i], (void *)dma_phys[i]);
-			dma_virt[i] = NULL;
-			break;
-		}
+	struct cma_allocation *alloc = NULL;
+
+	spin_lock(&cma_lock);
+	if (!list_empty(&cma_allocations)) {
+		alloc = list_first_entry(&cma_allocations,
+					 struct cma_allocation, list);
+		list_del(&alloc->list);
  	}
+	spin_unlock(&cma_lock);
+
+	if (alloc) {
+		dma_free_coherent(cma_dev, alloc->size, alloc->virt,
+				  alloc->dma);
+		_dev_info(cma_dev, "free virt: %p phys: %p\n",
+			  alloc->phys, (void *)alloc->dma);
+		kfree(alloc);
+	}
+
  	return 0;
  }

  /*
- * any write request will alloc coherent memory, eg.
- * echo 0 > /dev/cma_test
+ * Writes request specified number of pages, eg.
+ * echo 1024 > /dev/cma_test
   */
  static ssize_t
-cma_test_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+cma_test_write(struct file *file, const char __user *buf, size_t count,
+	       loff_t *ppos)
  {
-	int i;
+	struct cma_allocation *alloc;
  	int ret;

-	for (i = 0; i < CMA_NUM; i++) {
-		if (!dma_virt[i]) {
-			dma_virt[i] = dma_alloc_coherent(cma_dev, (i + 1) * SZ_1M, &dma_phys[i], GFP_KERNEL);
-
-			if (dma_virt[i]) {
-				void *p;
-				/* touch every page in the allocated memory */
-				for (p = dma_virt[i]; p <  dma_virt[i] + (i + 1) * SZ_1M; p += PAGE_SIZE)
-					*(u32 *)p = 0;
-
-				_dev_info(cma_dev, "alloc virt: %p phys: %p\n", dma_virt[i], (void *)dma_phys[i]);
-			} else {
-				dev_err(cma_dev, "no mem in CMA area\n");
-				ret = -ENOMEM;
-			}
-			break;
-		}
-	}
+	alloc = kmalloc(sizeof *alloc, GFP_KERNEL);
+	if (!alloc)
+		return -ENOMEM;
+
+	ret = kstrtouint_from_user(buf, count, 0, &alloc->size);
+	if (ret)
+		return ret;
+
+	if (!alloc->size)
+		return -EINVAL;
+
+	if (alloc->size > (ULONG_MAX << PAGE_SHIFT))
+		return -EOVERFLOW;

-	return count;
+	alloc->size >>= PAGE_SHIFT;
+	alloc->virt = dma_alloc_coherent(cma_dev, alloc->size,
+					 &alloc->dma, GFP_KERNEL);
+
+	if (alloc->virt) {
+		_dev_info(cma_dev, "alloc virt: %p phys: %p\n", alloc->virt,
+			  (void *)alloc->dma);
+
+		spin_lock(&cma_lock);
+		list_add_tail(&alloc->list, &cma_allocations);
+		spin_unlock(&cma_lock);
+
+		return count;
+	} else {
+		dev_err(cma_dev, "no mem in CMA area\n");
+		kfree(alloc);
+		return -ENOSPC;
+	}
  }

  static const struct file_operations cma_test_fops = {

> Signed-off-by: Barry Song <Baohua.Song@csr.com>
> ---
>  tools/cma/Makefile   |   13 ++++++
>  tools/cma/cma_test.c |  108 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 121 insertions(+), 0 deletions(-)
>  create mode 100644 tools/cma/Makefile
>  create mode 100644 tools/cma/cma_test.c
>
> diff --git a/tools/cma/Makefile b/tools/cma/Makefile
> new file mode 100644
> index 0000000..d15c2c0
> --- /dev/null
> +++ b/tools/cma/Makefile
> @@ -0,0 +1,13 @@
> +# Kernel modules
> +#
> +# To compile for ARM:
> +# make ARCH=arm CC=arm-none-linux-gnueabi-gcc
> +#
> +obj-m	+= cma_test.o
> +
> +build: kernel_modules
> +
> +kernel_modules:
> +	${MAKE} -C $(CURDIR)/../.. M=$(CURDIR)
> +clean:
> +	${MAKE} -C $(CURDIR)/../.. M=$(CURDIR) clean
> diff --git a/tools/cma/cma_test.c b/tools/cma/cma_test.c
> new file mode 100644
> index 0000000..3ee89f3
> --- /dev/null
> +++ b/tools/cma/cma_test.c
> @@ -0,0 +1,108 @@
> +/*
> + * kernel module helper for testing CMA
> + *
> + * Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
> + *
> + * Licensed under GPLv2 or later.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/fs.h>
> +#include <linux/miscdevice.h>
> +#include <linux/dma-mapping.h>
> +
> +#define CMA_NUM  10
> +static struct device *cma_dev;
> +static dma_addr_t dma_phys[CMA_NUM];
> +static void *dma_virt[CMA_NUM];
> +
> +/* any read request will free coherent memory, eg.
> + * cat /dev/cma_test
> + */
> +static ssize_t
> +cma_test_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
> +{
> +	int i;
> +
> +	for (i = 0; i < CMA_NUM; i++) {
> +		if (dma_virt[i]) {
> +			dma_free_coherent(cma_dev, (i + 1) * SZ_1M, dma_virt[i], dma_phys[i]);
> +			_dev_info(cma_dev, "free virt: %p phys: %p\n", dma_virt[i], (void *)dma_phys[i]);
> +			dma_virt[i] = NULL;
> +			break;
> +		}
> +	}
> +	return 0;
> +}
> +
> +/*
> + * any write request will alloc coherent memory, eg.
> + * echo 0 > /dev/cma_test
> + */
> +static ssize_t
> +cma_test_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
> +{
> +	int i;
> +	int ret;
> +
> +	for (i = 0; i < CMA_NUM; i++) {
> +		if (!dma_virt[i]) {
> +			dma_virt[i] = dma_alloc_coherent(cma_dev, (i + 1) * SZ_1M, &dma_phys[i], GFP_KERNEL);
> +
> +			if (dma_virt[i]) {
> +				void *p;
> +				/* touch every page in the allocated memory */
> +				for (p = dma_virt[i]; p <  dma_virt[i] + (i + 1) * SZ_1M; p += PAGE_SIZE)
> +					*(u32 *)p = 0;
> +
> +				_dev_info(cma_dev, "alloc virt: %p phys: %p\n", dma_virt[i], (void *)dma_phys[i]);
> +			} else {
> +				dev_err(cma_dev, "no mem in CMA area\n");
> +				ret = -ENOMEM;
> +			}
> +			break;
> +		}
> +	}
> +
> +	return count;
> +}
> +
> +static const struct file_operations cma_test_fops = {
> +	.owner =    THIS_MODULE,
> +	.read  =    cma_test_read,
> +	.write =    cma_test_write,
> +};
> +
> +static struct miscdevice cma_test_misc = {
> +	.name = "cma_test",
> +	.fops = &cma_test_fops,
> +};
> +
> +static int __init cma_test_init(void)
> +{
> +	int ret = 0;
> +
> +	ret = misc_register(&cma_test_misc);
> +	if (unlikely(ret)) {
> +		pr_err("failed to register cma test misc device!\n");
> +		return ret;
> +	}
> +	cma_dev = cma_test_misc.this_device;
> +	cma_dev->coherent_dma_mask = ~0;
> +	_dev_info(cma_dev, "registered.\n");
> +
> +	return ret;
> +}
> +module_init(cma_test_init);
> +
> +static void __exit cma_test_exit(void)
> +{
> +	misc_deregister(&cma_test_misc);
> +}
> +module_exit(cma_test_exit);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Barry Song <Baohua.Song@csr.com>");
> +MODULE_DESCRIPTION("kernel module to help the test of CMA");
> +MODULE_ALIAS("CMA test");


-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Micha? ?mina86? Nazarewicz    (o o)
ooo +----<email/xmpp: mpn@google.com>--------------ooO--(_)--Ooo--

[PATCH] MM: CMA: add a simple kernel module as the helper to test CMA

[Barry Song]

2012/3/2 Michal Nazarewicz <mina86@mina86.com>:
> On Fri, 02 Mar 2012 03:52:22 +0100, Barry Song <Barry.Song@csr.com> wrote:
>
>> From: Barry Song <Baohua.Song@csr.com>
>>
>> Any write request to /dev/cma_test will let the module to allocate memory
>> from
>> CMA, for example:
>>
>> 1st time
>> $ echo 0 > /dev/cma_test
>> will require cma_test to request 1MB
>> 2nd time
>> $ echo 0 > /dev/cma_test
>> will require cma_test to request 2MB
>>
>> Any read request to /dev/cma_test will let the module to free memory from
>> CMA,
>> for example:
>>
>> 1st time
>> $ cat /dev/cma_test
>> will require cma_test to free the 1MB allocated in the first write request
>> 2nd time
>> $ echo 0 > /dev/cma_test
>> will require cma_test to free the 2MB allocated in the second write
>> request
>
>
> Looks quite all right. ?It has a race condition but I guess for a test
> device it's
> not that big of a deal (I think the race cannot cause panic). ?Either way,
> would be
> nice if one could specify how much memory device should allocate. ?How about
> those
> changes:

Michal, i think these improvements have maken the cma_test much more
useful and flexible.

>
> diff --git a/tools/cma/cma_test.c b/tools/cma/cma_test.c
> index 3ee89f3..3d3b074 100644
> --- a/tools/cma/cma_test.c
> +++ b/tools/cma/cma_test.c
> @@ -6,66 +6,96 @@
>
> ?* Licensed under GPLv2 or later.
> ?*/
>
> -#include <linux/module.h>
> ?#include <linux/device.h>
> +#include <linux/dma-mapping.h>
> ?#include <linux/fs.h>
> +#include <linux/list.h>
> ?#include <linux/miscdevice.h>
> -#include <linux/dma-mapping.h>
> +#include <linux/module.h>
> +#include <linux/spinlock.h>
> +
> +struct cma_allocation {
> + ? ? ? struct list_head list;
> + ? ? ? unsigned long size;
> + ? ? ? dma_addr_t dma;
> + ? ? ? void *virt;
> +};
>
> -#define CMA_NUM ?10
> ?static struct device *cma_dev;
> -static dma_addr_t dma_phys[CMA_NUM];
> -static void *dma_virt[CMA_NUM];
> +static LIST_HEAD(cma_allocations);
> +static DEFINE_SPINLOCK(cma_lock);
>
>
> -/* any read request will free coherent memory, eg.
> +/*
> + * Any read request will free a single coherent memory, eg.
> ?* cat /dev/cma_test
> ?*/
> ?static ssize_t
>
> ?cma_test_read(struct file *file, char __user *buf, size_t count, loff_t
> *ppos)
> ?{
> - ? ? ? int i;
> -
> - ? ? ? for (i = 0; i < CMA_NUM; i++) {
> - ? ? ? ? ? ? ? if (dma_virt[i]) {
> - ? ? ? ? ? ? ? ? ? ? ? dma_free_coherent(cma_dev, (i + 1) * SZ_1M,
> dma_virt[i], dma_phys[i]);
> - ? ? ? ? ? ? ? ? ? ? ? _dev_info(cma_dev, "free virt: %p phys: %p\n",
> dma_virt[i], (void *)dma_phys[i]);
> - ? ? ? ? ? ? ? ? ? ? ? dma_virt[i] = NULL;
> - ? ? ? ? ? ? ? ? ? ? ? break;
> - ? ? ? ? ? ? ? }
> + ? ? ? struct cma_allocation *alloc = NULL;
> +
> + ? ? ? spin_lock(&cma_lock);
> + ? ? ? if (!list_empty(&cma_allocations)) {
> + ? ? ? ? ? ? ? alloc = list_first_entry(&cma_allocations,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct cma_allocation, list);
> + ? ? ? ? ? ? ? list_del(&alloc->list);
> ? ? ? ?}
> + ? ? ? spin_unlock(&cma_lock);
> +
> + ? ? ? if (alloc) {
> + ? ? ? ? ? ? ? dma_free_coherent(cma_dev, alloc->size, alloc->virt,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? alloc->dma);
>
> + ? ? ? ? ? ? ? _dev_info(cma_dev, "free virt: %p phys: %p\n",
> + ? ? ? ? ? ? ? ? ? ? ? ? alloc->phys, (void *)alloc->dma);
> + ? ? ? ? ? ? ? kfree(alloc);
> + ? ? ? }
> +
> ? ? ? ?return 0;
>
> ?}
>
> ?/*
> - * any write request will alloc coherent memory, eg.
> - * echo 0 > /dev/cma_test
> + * Writes request specified number of pages, eg.
> + * echo 1024 > /dev/cma_test
> ?*/
>
> ?static ssize_t
> -cma_test_write(struct file *file, const char __user *buf, size_t count,
> loff_t *ppos)
> +cma_test_write(struct file *file, const char __user *buf, size_t count,
> + ? ? ? ? ? ? ?loff_t *ppos)
> ?{
> - ? ? ? int i;
> + ? ? ? struct cma_allocation *alloc;
> ? ? ? ?int ret;
>
> - ? ? ? for (i = 0; i < CMA_NUM; i++) {
> - ? ? ? ? ? ? ? if (!dma_virt[i]) {
> - ? ? ? ? ? ? ? ? ? ? ? dma_virt[i] = dma_alloc_coherent(cma_dev, (i + 1) *
> SZ_1M, &dma_phys[i], GFP_KERNEL);
> -
> - ? ? ? ? ? ? ? ? ? ? ? if (dma_virt[i]) {
> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? void *p;
> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? /* touch every page in the allocated memory
> */
> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? for (p = dma_virt[i]; p < ?dma_virt[i] + (i
> + 1) * SZ_1M; p += PAGE_SIZE)
> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? *(u32 *)p = 0;
> -
> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? _dev_info(cma_dev, "alloc virt: %p phys:
> %p\n", dma_virt[i], (void *)dma_phys[i]);
> - ? ? ? ? ? ? ? ? ? ? ? } else {
> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? dev_err(cma_dev, "no mem in CMA area\n");
> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ret = -ENOMEM;
> - ? ? ? ? ? ? ? ? ? ? ? }
> - ? ? ? ? ? ? ? ? ? ? ? break;
> - ? ? ? ? ? ? ? }
> - ? ? ? }
> + ? ? ? alloc = kmalloc(sizeof *alloc, GFP_KERNEL);
> + ? ? ? if (!alloc)
> + ? ? ? ? ? ? ? return -ENOMEM;
> +
> + ? ? ? ret = kstrtouint_from_user(buf, count, 0, &alloc->size);
> + ? ? ? if (ret)
> + ? ? ? ? ? ? ? return ret;
> +
> + ? ? ? if (!alloc->size)
> + ? ? ? ? ? ? ? return -EINVAL;
> +
> + ? ? ? if (alloc->size > (ULONG_MAX << PAGE_SHIFT))
> + ? ? ? ? ? ? ? return -EOVERFLOW;
>
> - ? ? ? return count;
> + ? ? ? alloc->size >>= PAGE_SHIFT;
> + ? ? ? alloc->virt = dma_alloc_coherent(cma_dev, alloc->size,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?&alloc->dma, GFP_KERNEL);
> +
> + ? ? ? if (alloc->virt) {
> + ? ? ? ? ? ? ? _dev_info(cma_dev, "alloc virt: %p phys: %p\n", alloc->virt,
> + ? ? ? ? ? ? ? ? ? ? ? ? (void *)alloc->dma);
> +
> + ? ? ? ? ? ? ? spin_lock(&cma_lock);
> + ? ? ? ? ? ? ? list_add_tail(&alloc->list, &cma_allocations);
> + ? ? ? ? ? ? ? spin_unlock(&cma_lock);
> +
> + ? ? ? ? ? ? ? return count;
> + ? ? ? } else {
>
> + ? ? ? ? ? ? ? dev_err(cma_dev, "no mem in CMA area\n");
> + ? ? ? ? ? ? ? kfree(alloc);
> + ? ? ? ? ? ? ? return -ENOSPC;
> + ? ? ? }
>
> ?}
>
> ?static const struct file_operations cma_test_fops = {
>
>> Signed-off-by: Barry Song <Baohua.Song@csr.com>
>> ---
>> ?tools/cma/Makefile ? | ? 13 ++++++
>> ?tools/cma/cma_test.c | ?108
>> ++++++++++++++++++++++++++++++++++++++++++++++++++
>> ?2 files changed, 121 insertions(+), 0 deletions(-)
>> ?create mode 100644 tools/cma/Makefile
>> ?create mode 100644 tools/cma/cma_test.c
>>
>> diff --git a/tools/cma/Makefile b/tools/cma/Makefile
>> new file mode 100644
>> index 0000000..d15c2c0
>> --- /dev/null
>> +++ b/tools/cma/Makefile
>> @@ -0,0 +1,13 @@
>> +# Kernel modules
>> +#
>> +# To compile for ARM:
>> +# make ARCH=arm CC=arm-none-linux-gnueabi-gcc
>> +#
>> +obj-m ?+= cma_test.o
>> +
>> +build: kernel_modules
>> +
>> +kernel_modules:
>> + ? ? ? ${MAKE} -C $(CURDIR)/../.. M=$(CURDIR)
>> +clean:
>> + ? ? ? ${MAKE} -C $(CURDIR)/../.. M=$(CURDIR) clean
>> diff --git a/tools/cma/cma_test.c b/tools/cma/cma_test.c
>> new file mode 100644
>> index 0000000..3ee89f3
>> --- /dev/null
>> +++ b/tools/cma/cma_test.c
>> @@ -0,0 +1,108 @@
>> +/*
>> + * kernel module helper for testing CMA
>> + *
>> + * Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group
>> company.
>> + *
>> + * Licensed under GPLv2 or later.
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/device.h>
>> +#include <linux/fs.h>
>> +#include <linux/miscdevice.h>
>> +#include <linux/dma-mapping.h>
>> +
>> +#define CMA_NUM ?10
>> +static struct device *cma_dev;
>> +static dma_addr_t dma_phys[CMA_NUM];
>> +static void *dma_virt[CMA_NUM];
>> +
>> +/* any read request will free coherent memory, eg.
>> + * cat /dev/cma_test
>> + */
>> +static ssize_t
>> +cma_test_read(struct file *file, char __user *buf, size_t count, loff_t
>> *ppos)
>> +{
>> + ? ? ? int i;
>> +
>> + ? ? ? for (i = 0; i < CMA_NUM; i++) {
>> + ? ? ? ? ? ? ? if (dma_virt[i]) {
>> + ? ? ? ? ? ? ? ? ? ? ? dma_free_coherent(cma_dev, (i + 1) * SZ_1M,
>> dma_virt[i], dma_phys[i]);
>> + ? ? ? ? ? ? ? ? ? ? ? _dev_info(cma_dev, "free virt: %p phys: %p\n",
>> dma_virt[i], (void *)dma_phys[i]);
>> + ? ? ? ? ? ? ? ? ? ? ? dma_virt[i] = NULL;
>> + ? ? ? ? ? ? ? ? ? ? ? break;
>> + ? ? ? ? ? ? ? }
>> + ? ? ? }
>> + ? ? ? return 0;
>> +}
>> +
>> +/*
>> + * any write request will alloc coherent memory, eg.
>> + * echo 0 > /dev/cma_test
>> + */
>> +static ssize_t
>> +cma_test_write(struct file *file, const char __user *buf, size_t count,
>> loff_t *ppos)
>> +{
>> + ? ? ? int i;
>> + ? ? ? int ret;
>> +
>> + ? ? ? for (i = 0; i < CMA_NUM; i++) {
>> + ? ? ? ? ? ? ? if (!dma_virt[i]) {
>> + ? ? ? ? ? ? ? ? ? ? ? dma_virt[i] = dma_alloc_coherent(cma_dev, (i + 1)
>> * SZ_1M, &dma_phys[i], GFP_KERNEL);
>> +
>> + ? ? ? ? ? ? ? ? ? ? ? if (dma_virt[i]) {
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? void *p;
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? /* touch every page in the allocated
>> memory */
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? for (p = dma_virt[i]; p < ?dma_virt[i] +
>> (i + 1) * SZ_1M; p += PAGE_SIZE)
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? *(u32 *)p = 0;
>> +
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? _dev_info(cma_dev, "alloc virt: %p phys:
>> %p\n", dma_virt[i], (void *)dma_phys[i]);
>> + ? ? ? ? ? ? ? ? ? ? ? } else {
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? dev_err(cma_dev, "no mem in CMA area\n");
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ret = -ENOMEM;
>> + ? ? ? ? ? ? ? ? ? ? ? }
>> + ? ? ? ? ? ? ? ? ? ? ? break;
>> + ? ? ? ? ? ? ? }
>> + ? ? ? }
>> +
>> + ? ? ? return count;
>> +}
>> +
>> +static const struct file_operations cma_test_fops = {
>> + ? ? ? .owner = ? ?THIS_MODULE,
>> + ? ? ? .read ?= ? ?cma_test_read,
>> + ? ? ? .write = ? ?cma_test_write,
>> +};
>> +
>> +static struct miscdevice cma_test_misc = {
>> + ? ? ? .name = "cma_test",
>> + ? ? ? .fops = &cma_test_fops,
>> +};
>> +
>> +static int __init cma_test_init(void)
>> +{
>> + ? ? ? int ret = 0;
>> +
>> + ? ? ? ret = misc_register(&cma_test_misc);
>> + ? ? ? if (unlikely(ret)) {
>> + ? ? ? ? ? ? ? pr_err("failed to register cma test misc device!\n");
>> + ? ? ? ? ? ? ? return ret;
>> + ? ? ? }
>> + ? ? ? cma_dev = cma_test_misc.this_device;
>> + ? ? ? cma_dev->coherent_dma_mask = ~0;
>> + ? ? ? _dev_info(cma_dev, "registered.\n");
>> +
>> + ? ? ? return ret;
>> +}
>> +module_init(cma_test_init);
>> +
>> +static void __exit cma_test_exit(void)
>> +{
>> + ? ? ? misc_deregister(&cma_test_misc);
>> +}
>> +module_exit(cma_test_exit);
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Barry Song <Baohua.Song@csr.com>");
>> +MODULE_DESCRIPTION("kernel module to help the test of CMA");
>> +MODULE_ALIAS("CMA test");
>
>
>
> --
> Best regards, ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? _ ? ? _
> .o. | Liege of Serenely Enlightened Majesty of ? ? ?o' \,=./ `o
> ..o | Computer Science, ?Micha? ?mina86? Nazarewicz ? ?(o o)
> ooo +----<email/xmpp: mpn@google.com>--------------ooO--(_)--Ooo--
>
>

-barry

[PATCH] MM: CMA: add a simple kernel module as the helper to test CMA

[Michal Nazarewicz]

> 2012/3/2 Michal Nazarewicz <mina86@mina86.com>:
>> Looks quite all right.  It has a race condition but I guess for a test
>> device it's not that big of a deal (I think the race cannot cause
>> panic).  Either way, would be nice if one could specify how much memory
>> device should allocate.  How about those changes: [...]

On Fri, 02 Mar 2012 16:37:46 +0100, Barry Song <21cnbao@gmail.com> wrote:
> Michal, I think these improvements have maken the cma_test much more
> useful and flexible.

Sure, no problem, just squash it and resend the patch and I'll take one more
look at the result. :)

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Micha? ?mina86? Nazarewicz    (o o)
ooo +----<email/xmpp: mpn@google.com>--------------ooO--(_)--Ooo--