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authorJohn Keeping <john@metanate.com>2017-09-12 10:24:40 +0100
committerFelipe Balbi <felipe.balbi@linux.intel.com>2017-09-28 12:37:24 +0300
commitaddfc5823dbf3e6ed400e98e49c7e64b10e191d6 (patch)
tree14a9eb490836ad46c806a6dccd4c900b8c35e2de /drivers/usb
parent0a2ce62b61f2c76d0213edf4e37aaf54a8ddf295 (diff)
downloadlinux-addfc5823dbf3e6ed400e98e49c7e64b10e191d6.tar.bz2
usb: gadget: ffs: handle I/O completion in-order
By submitting completed transfers to the system workqueue there is no guarantee that completion events will be queued up in the correct order, as in multi-processor systems there is a thread running for each processor and the work items are not bound to a particular core. This means that several completions are in the queue at the same time, they may be processed in parallel and complete out of order, resulting in data appearing corrupt when read by userspace. Create a single-threaded workqueue for FunctionFS so that data completed requests is passed to userspace in the order in which they complete. Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: John Keeping <john@metanate.com> Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/gadget/function/f_fs.c17
-rw-r--r--drivers/usb/gadget/function/u_fs.h1
2 files changed, 14 insertions, 4 deletions
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 9990944a7245..8b342587f8ad 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -46,7 +46,8 @@
static void ffs_data_get(struct ffs_data *ffs);
static void ffs_data_put(struct ffs_data *ffs);
/* Creates new ffs_data object. */
-static struct ffs_data *__must_check ffs_data_new(void) __attribute__((malloc));
+static struct ffs_data *__must_check ffs_data_new(const char *dev_name)
+ __attribute__((malloc));
/* Opened counter handling. */
static void ffs_data_opened(struct ffs_data *ffs);
@@ -780,11 +781,12 @@ static void ffs_epfile_async_io_complete(struct usb_ep *_ep,
struct usb_request *req)
{
struct ffs_io_data *io_data = req->context;
+ struct ffs_data *ffs = io_data->ffs;
ENTER();
INIT_WORK(&io_data->work, ffs_user_copy_worker);
- schedule_work(&io_data->work);
+ queue_work(ffs->io_completion_wq, &io_data->work);
}
static void __ffs_epfile_read_buffer_free(struct ffs_epfile *epfile)
@@ -1500,7 +1502,7 @@ ffs_fs_mount(struct file_system_type *t, int flags,
if (unlikely(ret < 0))
return ERR_PTR(ret);
- ffs = ffs_data_new();
+ ffs = ffs_data_new(dev_name);
if (unlikely(!ffs))
return ERR_PTR(-ENOMEM);
ffs->file_perms = data.perms;
@@ -1610,6 +1612,7 @@ static void ffs_data_put(struct ffs_data *ffs)
BUG_ON(waitqueue_active(&ffs->ev.waitq) ||
waitqueue_active(&ffs->ep0req_completion.wait) ||
waitqueue_active(&ffs->wait));
+ destroy_workqueue(ffs->io_completion_wq);
kfree(ffs->dev_name);
kfree(ffs);
}
@@ -1642,7 +1645,7 @@ static void ffs_data_closed(struct ffs_data *ffs)
ffs_data_put(ffs);
}
-static struct ffs_data *ffs_data_new(void)
+static struct ffs_data *ffs_data_new(const char *dev_name)
{
struct ffs_data *ffs = kzalloc(sizeof *ffs, GFP_KERNEL);
if (unlikely(!ffs))
@@ -1650,6 +1653,12 @@ static struct ffs_data *ffs_data_new(void)
ENTER();
+ ffs->io_completion_wq = alloc_ordered_workqueue("%s", 0, dev_name);
+ if (!ffs->io_completion_wq) {
+ kfree(ffs);
+ return NULL;
+ }
+
refcount_set(&ffs->ref, 1);
atomic_set(&ffs->opened, 0);
ffs->state = FFS_READ_DESCRIPTORS;
diff --git a/drivers/usb/gadget/function/u_fs.h b/drivers/usb/gadget/function/u_fs.h
index 540f1c48c1a8..79f70ebf85dc 100644
--- a/drivers/usb/gadget/function/u_fs.h
+++ b/drivers/usb/gadget/function/u_fs.h
@@ -279,6 +279,7 @@ struct ffs_data {
} file_perms;
struct eventfd_ctx *ffs_eventfd;
+ struct workqueue_struct *io_completion_wq;
bool no_disconnect;
struct work_struct reset_work;