[PATCH v4] mm: cma: add a simple kernel module as the helper to test CMA

[PATCH v4] 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 1024 > /dev/cma_test
will require cma_test to request 1MB(1024KB)
2nd time
$ echo 2048 > /dev/cma_test
will require cma_test to request 2MB(2048KB)

Any read request to /dev/cma_test will let the module to free the 1st valid
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
$ cat /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 |  140 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 153 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..7eb96db
--- /dev/null
+++ b/tools/cma/cma_test.c
@@ -0,0 +1,140 @@
+/*
+ * kernel module helper for testing CMA
+ *
+ * Copyright (c) 2012 Cambridge Silicon Radio Limited, a CSR plc group company.
+ *
+ * Licensed under GPLv2 or later.
+ */
+
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+struct cma_allocation {
+	struct list_head list;
+	size_t size;
+	dma_addr_t dma;
+	void *virt;
+};
+
+static struct device *cma_dev;
+static LIST_HEAD(cma_allocations);
+static DEFINE_SPINLOCK(cma_lock);
+
+/*
+ * any read request will free the 1st allocated 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)
+{
+	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)
+		return -EIDRM;
+
+	dma_free_coherent(cma_dev, alloc->size, alloc->virt,
+		alloc->dma);
+
+	_dev_info(cma_dev, "free: CM virt: %p dma: %p size:%zuK\n",
+		alloc->virt, (void *)alloc->dma, alloc->size / SZ_1K);
+	kfree(alloc);
+
+	return 0;
+}
+
+/*
+ * any write request will alloc a new coherent memory, eg.
+ * echo 1024 > /dev/cma_test
+ * will request 1024KiB by CMA
+ */
+static ssize_t
+cma_test_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+{
+	struct cma_allocation *alloc;
+	unsigned long size;
+	int ret;
+
+	ret = kstrtoul_from_user(buf, count, 0, &size);
+	if (ret)
+		return ret;
+
+	if (!size)
+		return -EINVAL;
+
+	if (size > ~(size_t)0 / SZ_1K)
+		return -EOVERFLOW;
+
+	alloc = kmalloc(sizeof *alloc, GFP_KERNEL);
+	if (!alloc)
+		return -ENOMEM;
+
+	alloc->size = size * SZ_1K;
+	alloc->virt = dma_alloc_coherent(cma_dev, alloc->size,
+		&alloc->dma, GFP_KERNEL);
+
+	if (alloc->virt) {
+		_dev_info(cma_dev, "alloc: virt: %p dma: %p size: %zuK\n",
+			alloc->virt, (void *)alloc->dma, alloc->size / SZ_1K);
+
+		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 = {
+	.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 = 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 0;
+}
+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



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[PATCH v4] mm: cma: add a simple kernel module as the helper to test CMA

[Michal Nazarewicz]

On Wed, 07 Mar 2012 12:37:39 +0100, Barry Song <Barry.Song@csr.com> wrote:
> Any write request to /dev/cma_test will let the module to allocate memory from
> CMA, for example:
>
> 1st time
> $ echo 1024 > /dev/cma_test
> will require cma_test to request 1MB(1024KB)
> 2nd time
> $ echo 2048 > /dev/cma_test
> will require cma_test to request 2MB(2048KB)
>
> Any read request to /dev/cma_test will let the module to free the 1st valid
> 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
> $ cat /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>

Reviewed-by: Michal Nazarewicz <mina86@mina86.com>

-- 
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 v4] mm: cma: add a simple kernel module as the helper to test CMA

[Marek Szyprowski]

Hello,

On Wednesday, March 07, 2012 12:38 PM Barry Song 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 1024 > /dev/cma_test
> will require cma_test to request 1MB(1024KB)
> 2nd time
> $ echo 2048 > /dev/cma_test
> will require cma_test to request 2MB(2048KB)
> 
> Any read request to /dev/cma_test will let the module to free the 1st valid
> 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
> $ cat /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 |  140 ++++++++++++++++++++++++++++++++++++++++++++++++++

I'm sorry for such a long delay in processing this patch, but I wanted first to be sure
that the core CMA code gets into mainline, then I got busy with other dma-mapping 
related stuff. 

IMHO the right place for such code is in drivers/misc instead of tools/cma. 

This patch contains a kernel module source code so it should be put with other kernel
modules. tools/ directory is aimed to contain user space code useful for developing and
testing Linux kernel.

Make sure that you also add Greg Kroah-Hartman <gregkh@linuxfoundation.org> on CC:,
he maintains misc drivers.

> (snipped)

Best regards
-- 
Marek Szyprowski
Samsung Poland R&D Center

[PATCH v4] mm: cma: add a simple kernel module as the helper to test CMA

[Barry Song]

Hi Marek,

2012/7/3 Marek Szyprowski <m.szyprowski@samsung.com>:
> Hello,
>
> On Wednesday, March 07, 2012 12:38 PM Barry Song 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 1024 > /dev/cma_test
>> will require cma_test to request 1MB(1024KB)
>> 2nd time
>> $ echo 2048 > /dev/cma_test
>> will require cma_test to request 2MB(2048KB)
>>
>> Any read request to /dev/cma_test will let the module to free the 1st valid
>> 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
>> $ cat /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 |  140 ++++++++++++++++++++++++++++++++++++++++++++++++++
>
> I'm sorry for such a long delay in processing this patch, but I wanted first to be sure
> that the core CMA code gets into mainline, then I got busy with other dma-mapping
> related stuff.

now CMA stuff has been in mainline, i think it makes more senses if
you involve this while you let people merge CMA because it is a CMA
test component.

>
> IMHO the right place for such code is in drivers/misc instead of tools/cma.
>
> This patch contains a kernel module source code so it should be put with other kernel
> modules. tools/ directory is aimed to contain user space code useful for developing and
> testing Linux kernel.

this one is aiming to test CMA, it should be in tools/ as Michal
Nazarewicz and i have talked about that.
it is not a real driver at all.

>
> Make sure that you also add Greg Kroah-Hartman <gregkh@linuxfoundation.org> on CC:,
> he maintains misc drivers.
>
>> (snipped)
>
> Best regards
> --
> Marek Szyprowski
> Samsung Poland R&D Center

-barry

[PATCH v4] mm: cma: add a simple kernel module as the helper to test CMA

[Michal Nazarewicz]

> 2012/7/3 Marek Szyprowski <m.szyprowski@samsung.com>:
>> IMHO the right place for such code is in drivers/misc instead of tools/cma.
>>
>> This patch contains a kernel module source code so it should be put with other kernel
>> modules. tools/ directory is aimed to contain user space code useful for developing and
>> testing Linux kernel.

On Tue, 03 Jul 2012 09:39:34 +0200, Barry Song <21cnbao@gmail.com> wrote:
> this one is aiming to test CMA, it should be in tools/ as Michal
> Nazarewicz and i have talked about that.
> it is not a real driver at all.

Yeah, I feel like it's better placed in tools/ not to pollute other directories with
drivers that are of no use to regular users.  I don't have strong feelings about it
though, so I'm fine either way.

-- 
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 v4] mm: cma: add a simple kernel module as the helper to test CMA

[Marek Szyprowski]

Hello,

On Tuesday, July 03, 2012 2:54 PM Michal Nazarewicz wrote:

> > 2012/7/3 Marek Szyprowski <m.szyprowski@samsung.com>:
> >> IMHO the right place for such code is in drivers/misc instead of tools/cma.
> >>
> >> This patch contains a kernel module source code so it should be put with other kernel
> >> modules. tools/ directory is aimed to contain user space code useful for developing and
> >> testing Linux kernel.
> 
> On Tue, 03 Jul 2012 09:39:34 +0200, Barry Song <21cnbao@gmail.com> wrote:
> > this one is aiming to test CMA, it should be in tools/ as Michal
> > Nazarewicz and i have talked about that.
> > it is not a real driver at all.
> 
> Yeah, I feel like it's better placed in tools/ not to pollute other directories with
> drivers that are of no use to regular users.  I don't have strong feelings about it
> though, so I'm fine either way.

Other test devices/drivers are in drivers directory (drivers/usb/misc/usbtest.c for
example), I don't see any good reason for polluting tools/ directory with kernel code. 

IMHO the right person to decide if it makes sense to have such drivers in drivers/mics/
or tools/cma/ is Greg KH. Barry, please resend it and ask Greg for the decision.

Best regards
-- 
Marek Szyprowski
Samsung Poland R&D Center

[PATCH v4] mm: cma: add a simple kernel module as the helper to test CMA

[Barry Song]

Hi Marek,

2012/7/4 Marek Szyprowski <m.szyprowski@samsung.com>:
> Hello,
>
> On Tuesday, July 03, 2012 2:54 PM Michal Nazarewicz wrote:
>
>> > 2012/7/3 Marek Szyprowski <m.szyprowski@samsung.com>:
>> >> IMHO the right place for such code is in drivers/misc instead of tools/cma.
>> >>
>> >> This patch contains a kernel module source code so it should be put with other kernel
>> >> modules. tools/ directory is aimed to contain user space code useful for developing and
>> >> testing Linux kernel.
>>
>> On Tue, 03 Jul 2012 09:39:34 +0200, Barry Song <21cnbao@gmail.com> wrote:
>> > this one is aiming to test CMA, it should be in tools/ as Michal
>> > Nazarewicz and i have talked about that.
>> > it is not a real driver at all.
>>
>> Yeah, I feel like it's better placed in tools/ not to pollute other directories with
>> drivers that are of no use to regular users.  I don't have strong feelings about it
>> though, so I'm fine either way.
>
> Other test devices/drivers are in drivers directory (drivers/usb/misc/usbtest.c for
> example), I don't see any good reason for polluting tools/ directory with kernel code.
>
> IMHO the right person to decide if it makes sense to have such drivers in drivers/mics/
> or tools/cma/ is Greg KH. Barry, please resend it and ask Greg for the decision.

sure. thanks.

>
> Best regards
> --
> Marek Szyprowski
> Samsung Poland R&D Center
>
>

-barry

[PATCH v4] mm: cma: add a simple kernel module as the helper to test CMA

[Barry Song]

2012/7/4 Barry Song <21cnbao@gmail.com>:
> Hi Marek,
>
> 2012/7/4 Marek Szyprowski <m.szyprowski@samsung.com>:
>> Hello,
>>
>> On Tuesday, July 03, 2012 2:54 PM Michal Nazarewicz wrote:
>>
>>> > 2012/7/3 Marek Szyprowski <m.szyprowski@samsung.com>:
>>> >> IMHO the right place for such code is in drivers/misc instead of tools/cma.
>>> >>
>>> >> This patch contains a kernel module source code so it should be put with other kernel
>>> >> modules. tools/ directory is aimed to contain user space code useful for developing and
>>> >> testing Linux kernel.
>>>
>>> On Tue, 03 Jul 2012 09:39:34 +0200, Barry Song <21cnbao@gmail.com> wrote:
>>> > this one is aiming to test CMA, it should be in tools/ as Michal
>>> > Nazarewicz and i have talked about that.
>>> > it is not a real driver at all.
>>>
>>> Yeah, I feel like it's better placed in tools/ not to pollute other directories with
>>> drivers that are of no use to regular users.  I don't have strong feelings about it
>>> though, so I'm fine either way.
>>
>> Other test devices/drivers are in drivers directory (drivers/usb/misc/usbtest.c for
>> example), I don't see any good reason for polluting tools/ directory with kernel code.
>>
>> IMHO the right person to decide if it makes sense to have such drivers in drivers/mics/
>> or tools/cma/ is Greg KH. Barry, please resend it and ask Greg for the decision.
>
> sure. thanks.

and BTW, if the only issue is the dir it should be placed to let Greg
decide, would i also have your reviewed-by before sending to Greg KH?

>
>>
>> Best regards
>> --
>> Marek Szyprowski
>> Samsung Poland R&D Center
>>

-barry