[RFC] ion:change ion_cma_allocate return error value

[RFC] ion:change ion_cma_allocate return error value

[Wang, Yalin]

This patch change the error return value from -1 to -ENOMEM,
so that userspace can get the correct errno, otherwise,
-1 will be -EPERM, userspace will print permission deny for allocation
failure.

Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com>
---
 drivers/staging/android/ion/ion_cma_heap.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/android/ion/ion_cma_heap.c b/drivers/staging/android/ion/ion_cma_heap.c
index f4211f1..55bcaec2 100644
--- a/drivers/staging/android/ion/ion_cma_heap.c
+++ b/drivers/staging/android/ion/ion_cma_heap.c
@@ -24,8 +24,6 @@
 #include "ion.h"
 #include "ion_priv.h"
 
-#define ION_CMA_ALLOCATE_FAILED -1
-
 struct ion_cma_heap {
 	struct ion_heap heap;
 	struct device *dev;
@@ -59,7 +57,7 @@ static int ion_cma_allocate(struct ion_heap *heap, struct ion_buffer *buffer,
 
 	info = kzalloc(sizeof(struct ion_cma_buffer_info), GFP_KERNEL);
 	if (!info)
-		return ION_CMA_ALLOCATE_FAILED;
+		return -ENOMEM;
 
 	info->cpu_addr = dma_alloc_coherent(dev, len, &(info->handle),
 						GFP_HIGHUSER | __GFP_ZERO);
@@ -87,7 +85,7 @@ free_mem:
 	dma_free_coherent(dev, len, info->cpu_addr, info->handle);
 err:
 	kfree(info);
-	return ION_CMA_ALLOCATE_FAILED;
+	return -ENOMEM;
 }
 
 static void ion_cma_free(struct ion_buffer *buffer)
-- 
2.2.2

Re: [RFC] ion:change ion_cma_allocate return error value

[Dan Carpenter]

On Tue, Jan 27, 2015 at 02:04:21PM +0800, Wang, Yalin wrote:
> This patch change the error return value from -1 to -ENOMEM,
> so that userspace can get the correct errno, otherwise,
> -1 will be -EPERM, userspace will print permission deny for allocation
> failure.
> 
> Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com>

Looks good.

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>

regards,
dan carpenter

Re: [RFC] ion:change ion_cma_allocate return error value

['gregkh@linuxfoundation.org']

On Tue, Jan 27, 2015 at 02:04:21PM +0800, Wang, Yalin wrote:
> This patch change the error return value from -1 to -ENOMEM,
> so that userspace can get the correct errno, otherwise,
> -1 will be -EPERM, userspace will print permission deny for allocation
> failure.
> 
> Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com>
> ---
>  drivers/staging/android/ion/ion_cma_heap.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)

Don't you also need to now change userspace code to properly handle
these errors?

greg k-h

RE: [RFC] ion:change ion_cma_allocate return error value

[Wang, Yalin]

> -----Original Message-----
> From: 'gregkh@linuxfoundation.org' [mailto:gregkh@linuxfoundation.org]
> Sent: Thursday, January 29, 2015 2:45 AM
> To: Wang, Yalin
> Cc: 'tranmanphong@gmail.com'; 'fabio.estevam@freescale.com';
> 'prime.zeng@huawei.com'; 'devel@driverdev.osuosl.org'; 'linux-
> kernel@vger.kernel.org'; Gao, Neil
> Subject: Re: [RFC] ion:change ion_cma_allocate return error value
> 
> On Tue, Jan 27, 2015 at 02:04:21PM +0800, Wang, Yalin wrote:
> > This patch change the error return value from -1 to -ENOMEM, so that
> > userspace can get the correct errno, otherwise,
> > -1 will be -EPERM, userspace will print permission deny for allocation
> > failure.
> >
> > Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com>
> > ---
> >  drivers/staging/android/ion/ion_cma_heap.c | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> Don't you also need to now change userspace code to properly handle these
> errors?
> 
No, because userspace use strerror() to print errno,
It will print correct error string depending on kernel return
Errno.