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Subject[PATCH v5 4/5] usb: f_fs: check quirk to pad epout buf size when not aligned to maxpacketsize
Date
From: Michal Nazarewicz <mina86@mina86.com>

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: Michal Nazarewicz <mina86@mina86.com>
Acked-by: David Cohen <david.a.cohen@linux.intel.com>
---
drivers/usb/gadget/f_fs.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index f1563c47e0c2..c49288778fe0 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -755,8 +755,9 @@ 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;
- ssize_t ret;
+ ssize_t ret, data_len;
char *data;
int halt;

@@ -789,7 +790,14 @@ static ssize_t ffs_epfile_io(struct file *file,

/* Allocate & copy */
if (!halt) {
- data = kmalloc(len, GFP_KERNEL);
+ /*
+ * Controller requires buffer size to be aligned to
+ * maxpacketsize of an out endpoint.
+ */
+ data_len = read && gadget->quirk_ep_out_aligned_size ?
+ usb_ep_align_maxpacketsize(ep->ep, len) : len;
+
+ data = kmalloc(data_len, GFP_KERNEL);
if (unlikely(!data))
return -ENOMEM;

@@ -826,7 +834,7 @@ static ssize_t ffs_epfile_io(struct file *file,
req->context = &done;
req->complete = ffs_epfile_io_complete;
req->buf = data;
- req->length = len;
+ req->length = data_len;

ret = usb_ep_queue(ep->ep, req, GFP_ATOMIC);

@@ -838,9 +846,16 @@ static ssize_t ffs_epfile_io(struct file *file,
ret = -EINTR;
usb_ep_dequeue(ep->ep, req);
} else {
+ /*
+ * XXX We may end up silently droping data here.
+ * Since data_len (i.e. req->length) may be bigger
+ * than len (after being rounded up to maxpacketsize),
+ * we may end up with more data then user space has
+ * space for.
+ */
ret = ep->status;
if (read && ret > 0 &&
- unlikely(copy_to_user(buf, data, ret)))
+ unlikely(copy_to_user(buf, data, min(ret, len))))
ret = -EFAULT;
}
}
--
1.8.4.rc3


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