Re: [PATCH v3 2/3] usb: ffs: check quirk to pad epout buf size when not aligned to maxpacketsize

2013-11-04 Thread David Cohen 

Hi Alan,

Appreciate your comments. Please, see my reply.

On 10/30/2013 10:35 AM, Alan Stern wrote:

On Wed, 30 Oct 2013, David Cohen wrote:


Check gadget.quirk_ep_out_aligned_size to decide if buffer size requires
to be aligned to maxpacketsize of an out endpoint. ffs_epfile_io() needs
to pad epout buffer to match above condition if quirk is found.

Signed-off-by: David Cohen 
---
  drivers/usb/gadget/f_fs.c | 17 +
  1 file changed, 17 insertions(+)

diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index 75e4b78..b49dd55 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -755,10 +755,12 @@ static ssize_t ffs_epfile_io(struct file *file,
 char __user *buf, size_t len, int read)
  {
struct ffs_epfile *epfile = file->private_data;
+   struct usb_gadget *gadget = epfile->ffs->gadget;
struct ffs_ep *ep;
char *data = NULL;
ssize_t ret;
int halt;
+   size_t orig_len = len;

goto first_try;
do {
@@ -794,6 +796,21 @@ first_try:
goto error;
}

+   /*
+* Controller requires buffer size to be aligned to
+* maxpacketsize of an out endpoint.
+*/
+   if (gadget->quirk_ep_out_aligned_size && read &&
+   !IS_ALIGNED(len, ep->ep->desc->wMaxPacketSize)) {


IS_ALIGNED works only when the second argument is a power of 2.

Interrupt endpoints are not required to have maxpacket sizes that are
powers of 2.  Does this code ever get used for an interrupt endpoint?


That's a good point. It won't use interrupt ep on the case I am working
on, but f_fs allows it. I'll cover both cases in next patchset.




+   size_t old_len = len;


Why add old_len here when you added orig_len above?


See below.




+   len = roundup(orig_len,
+ (size_t)ep->ep->desc->wMaxPacketSize);
+   if (unlikely(data) && len > old_len) {


If the original value wasn't aligned, how can len fail to be > old_len?


This code is inside a loop. There is an unlikely case explained in the
end to loop again if ep got disabled or changed while acquiring mutex.
If that happens, I want to avoid to re-allocate buffer if previous size
was already enough. Since 'len' gets updated when aligning buf size, we
need to keep track of 'orig_len' to do only minimum necessary pad on
new alignment. 'old_len' is used to save previous value to decide for
new allocation or not. But maybe I should change it to something more
accurate like 'buf_size' or 'alloc_size'.

Br, David Cohen
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Re: [PATCH v3 2/3] usb: ffs: check quirk to pad epout buf size when not aligned to maxpacketsize

2013-11-04 Thread David Cohen 

Hi Alan,

Appreciate your comments. Please, see my reply.

On 10/30/2013 10:35 AM, Alan Stern wrote:

On Wed, 30 Oct 2013, David Cohen wrote:


Check gadget.quirk_ep_out_aligned_size to decide if buffer size requires
to be aligned to maxpacketsize of an out endpoint. ffs_epfile_io() needs
to pad epout buffer to match above condition if quirk is found.

Signed-off-by: David Cohen david.a.co...@linux.intel.com
---
  drivers/usb/gadget/f_fs.c | 17 +
  1 file changed, 17 insertions(+)

diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index 75e4b78..b49dd55 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -755,10 +755,12 @@ static ssize_t ffs_epfile_io(struct file *file,
 char __user *buf, size_t len, int read)
  {
struct ffs_epfile *epfile = file-private_data;
+   struct usb_gadget *gadget = epfile-ffs-gadget;
struct ffs_ep *ep;
char *data = NULL;
ssize_t ret;
int halt;
+   size_t orig_len = len;

goto first_try;
do {
@@ -794,6 +796,21 @@ first_try:
goto error;
}

+   /*
+* Controller requires buffer size to be aligned to
+* maxpacketsize of an out endpoint.
+*/
+   if (gadget-quirk_ep_out_aligned_size  read 
+   !IS_ALIGNED(len, ep-ep-desc-wMaxPacketSize)) {


IS_ALIGNED works only when the second argument is a power of 2.

Interrupt endpoints are not required to have maxpacket sizes that are
powers of 2.  Does this code ever get used for an interrupt endpoint?


That's a good point. It won't use interrupt ep on the case I am working
on, but f_fs allows it. I'll cover both cases in next patchset.




+   size_t old_len = len;


Why add old_len here when you added orig_len above?


See below.




+   len = roundup(orig_len,
+ (size_t)ep-ep-desc-wMaxPacketSize);
+   if (unlikely(data)  len  old_len) {


If the original value wasn't aligned, how can len fail to be  old_len?


This code is inside a loop. There is an unlikely case explained in the
end to loop again if ep got disabled or changed while acquiring mutex.
If that happens, I want to avoid to re-allocate buffer if previous size
was already enough. Since 'len' gets updated when aligning buf size, we
need to keep track of 'orig_len' to do only minimum necessary pad on
new alignment. 'old_len' is used to save previous value to decide for
new allocation or not. But maybe I should change it to something more
accurate like 'buf_size' or 'alloc_size'.

Br, David Cohen
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Re: [PATCH v3 2/3] usb: ffs: check quirk to pad epout buf size when not aligned to maxpacketsize

2013-10-30 Thread Alan Stern 
On Wed, 30 Oct 2013, David Cohen wrote:

> Check gadget.quirk_ep_out_aligned_size to decide if buffer size requires
> to be aligned to maxpacketsize of an out endpoint. ffs_epfile_io() needs
> to pad epout buffer to match above condition if quirk is found.
> 
> Signed-off-by: David Cohen 
> ---
>  drivers/usb/gadget/f_fs.c | 17 +
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
> index 75e4b78..b49dd55 100644
> --- a/drivers/usb/gadget/f_fs.c
> +++ b/drivers/usb/gadget/f_fs.c
> @@ -755,10 +755,12 @@ static ssize_t ffs_epfile_io(struct file *file,
>char __user *buf, size_t len, int read)
>  {
>   struct ffs_epfile *epfile = file->private_data;
> + struct usb_gadget *gadget = epfile->ffs->gadget;
>   struct ffs_ep *ep;
>   char *data = NULL;
>   ssize_t ret;
>   int halt;
> + size_t orig_len = len;
>  
>   goto first_try;
>   do {
> @@ -794,6 +796,21 @@ first_try:
>   goto error;
>   }
>  
> + /*
> +  * Controller requires buffer size to be aligned to
> +  * maxpacketsize of an out endpoint.
> +  */
> + if (gadget->quirk_ep_out_aligned_size && read &&
> + !IS_ALIGNED(len, ep->ep->desc->wMaxPacketSize)) {

IS_ALIGNED works only when the second argument is a power of 2.  

Interrupt endpoints are not required to have maxpacket sizes that are 
powers of 2.  Does this code ever get used for an interrupt endpoint?

> + size_t old_len = len;

Why add old_len here when you added orig_len above?

> + len = roundup(orig_len,
> +   (size_t)ep->ep->desc->wMaxPacketSize);
> + if (unlikely(data) && len > old_len) {

If the original value wasn't aligned, how can len fail to be > old_len?

> + kfree(data);
> + data = NULL;
> + }
> + }
> +
>   /* Allocate & copy */
>   if (!halt && !data) {
>   data = kzalloc(len, GFP_KERNEL);

Alan Stern

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[PATCH v3 2/3] usb: ffs: check quirk to pad epout buf size when not aligned to maxpacketsize

2013-10-30 Thread David Cohen 
Check gadget.quirk_ep_out_aligned_size to decide if buffer size requires
to be aligned to maxpacketsize of an out endpoint. ffs_epfile_io() needs
to pad epout buffer to match above condition if quirk is found.

Signed-off-by: David Cohen 
---
 drivers/usb/gadget/f_fs.c | 17 +
 1 file changed, 17 insertions(+)

diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index 75e4b78..b49dd55 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -755,10 +755,12 @@ static ssize_t ffs_epfile_io(struct file *file,
 char __user *buf, size_t len, int read)
 {
struct ffs_epfile *epfile = file->private_data;
+   struct usb_gadget *gadget = epfile->ffs->gadget;
struct ffs_ep *ep;
char *data = NULL;
ssize_t ret;
int halt;
+   size_t orig_len = len;
 
goto first_try;
do {
@@ -794,6 +796,21 @@ first_try:
goto error;
}
 
+   /*
+* Controller requires buffer size to be aligned to
+* maxpacketsize of an out endpoint.
+*/
+   if (gadget->quirk_ep_out_aligned_size && read &&
+   !IS_ALIGNED(len, ep->ep->desc->wMaxPacketSize)) {
+   size_t old_len = len;
+   len = roundup(orig_len,
+ (size_t)ep->ep->desc->wMaxPacketSize);
+   if (unlikely(data) && len > old_len) {
+   kfree(data);
+   data = NULL;
+   }
+   }
+
/* Allocate & copy */
if (!halt && !data) {
data = kzalloc(len, GFP_KERNEL);
-- 
1.8.4.rc3

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[PATCH v3 2/3] usb: ffs: check quirk to pad epout buf size when not aligned to maxpacketsize

2013-10-30 Thread David Cohen 
Check gadget.quirk_ep_out_aligned_size to decide if buffer size requires
to be aligned to maxpacketsize of an out endpoint. ffs_epfile_io() needs
to pad epout buffer to match above condition if quirk is found.

Signed-off-by: David Cohen david.a.co...@linux.intel.com
---
 drivers/usb/gadget/f_fs.c | 17 +
 1 file changed, 17 insertions(+)

diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index 75e4b78..b49dd55 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -755,10 +755,12 @@ static ssize_t ffs_epfile_io(struct file *file,
 char __user *buf, size_t len, int read)
 {
struct ffs_epfile *epfile = file-private_data;
+   struct usb_gadget *gadget = epfile-ffs-gadget;
struct ffs_ep *ep;
char *data = NULL;
ssize_t ret;
int halt;
+   size_t orig_len = len;
 
goto first_try;
do {
@@ -794,6 +796,21 @@ first_try:
goto error;
}
 
+   /*
+* Controller requires buffer size to be aligned to
+* maxpacketsize of an out endpoint.
+*/
+   if (gadget-quirk_ep_out_aligned_size  read 
+   !IS_ALIGNED(len, ep-ep-desc-wMaxPacketSize)) {
+   size_t old_len = len;
+   len = roundup(orig_len,
+ (size_t)ep-ep-desc-wMaxPacketSize);
+   if (unlikely(data)  len  old_len) {
+   kfree(data);
+   data = NULL;
+   }
+   }
+
/* Allocate  copy */
if (!halt  !data) {
data = kzalloc(len, GFP_KERNEL);
-- 
1.8.4.rc3

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Re: [PATCH v3 2/3] usb: ffs: check quirk to pad epout buf size when not aligned to maxpacketsize

2013-10-30 Thread Alan Stern 
On Wed, 30 Oct 2013, David Cohen wrote:

 Check gadget.quirk_ep_out_aligned_size to decide if buffer size requires
 to be aligned to maxpacketsize of an out endpoint. ffs_epfile_io() needs
 to pad epout buffer to match above condition if quirk is found.
 
 Signed-off-by: David Cohen david.a.co...@linux.intel.com
 ---
  drivers/usb/gadget/f_fs.c | 17 +
  1 file changed, 17 insertions(+)
 
 diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
 index 75e4b78..b49dd55 100644
 --- a/drivers/usb/gadget/f_fs.c
 +++ b/drivers/usb/gadget/f_fs.c
 @@ -755,10 +755,12 @@ static ssize_t ffs_epfile_io(struct file *file,
char __user *buf, size_t len, int read)
  {
   struct ffs_epfile *epfile = file-private_data;
 + struct usb_gadget *gadget = epfile-ffs-gadget;
   struct ffs_ep *ep;
   char *data = NULL;
   ssize_t ret;
   int halt;
 + size_t orig_len = len;
  
   goto first_try;
   do {
 @@ -794,6 +796,21 @@ first_try:
   goto error;
   }
  
 + /*
 +  * Controller requires buffer size to be aligned to
 +  * maxpacketsize of an out endpoint.
 +  */
 + if (gadget-quirk_ep_out_aligned_size  read 
 + !IS_ALIGNED(len, ep-ep-desc-wMaxPacketSize)) {

IS_ALIGNED works only when the second argument is a power of 2.  

Interrupt endpoints are not required to have maxpacket sizes that are 
powers of 2.  Does this code ever get used for an interrupt endpoint?

 + size_t old_len = len;

Why add old_len here when you added orig_len above?

 + len = roundup(orig_len,
 +   (size_t)ep-ep-desc-wMaxPacketSize);
 + if (unlikely(data)  len  old_len) {

If the original value wasn't aligned, how can len fail to be  old_len?

 + kfree(data);
 + data = NULL;
 + }
 + }
 +
   /* Allocate  copy */
   if (!halt  !data) {
   data = kzalloc(len, GFP_KERNEL);

Alan Stern

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