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Message-ID: <lsq.1496331796.611665099@decadent.org.uk>
Date: Thu, 01 Jun 2017 16:43:16 +0100
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC: akpm@...ux-foundation.org,
"Felipe Balbi" <felipe.balbi@...ux.intel.com>,
"Krzysztof Opasiak" <k.opasiak@...sung.com>,
"David Lechner" <david@...hnology.com>,
"Krzysztof Opasiak" <kopasiak90@...il.com>
Subject: [PATCH 3.16 069/212] usb: gadget: f_hid: Use spinlock instead of
mutex
3.16.44-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Krzysztof Opasiak <kopasiak90@...il.com>
commit 33e4c1a9987a1fc3b42c3b534100b5b006d55c61 upstream.
As IN request has to be allocated in set_alt() and released in
disable() we cannot use mutex to protect it as we cannot sleep
in those funcitons. Let's replace this mutex with a spinlock.
Tested-by: David Lechner <david@...hnology.com>
Signed-off-by: Krzysztof Opasiak <k.opasiak@...sung.com>
Signed-off-by: Felipe Balbi <felipe.balbi@...ux.intel.com>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
drivers/usb/gadget/f_hid.c | 57 ++++++++++++++++++++++---------------
1 file changed, 34 insertions(+), 23 deletions(-)
--- a/drivers/usb/gadget/f_hid.c
+++ b/drivers/usb/gadget/f_hid.c
@@ -44,12 +44,12 @@ struct f_hidg {
/* recv report */
struct list_head completed_out_req;
- spinlock_t spinlock;
+ spinlock_t read_spinlock;
wait_queue_head_t read_queue;
unsigned int qlen;
/* send report */
- struct mutex lock;
+ spinlock_t write_spinlock;
bool write_pending;
wait_queue_head_t write_queue;
struct usb_request *req;
@@ -178,20 +178,20 @@ static ssize_t f_hidg_read(struct file *
if (!access_ok(VERIFY_WRITE, buffer, count))
return -EFAULT;
- spin_lock_irqsave(&hidg->spinlock, flags);
+ spin_lock_irqsave(&hidg->read_spinlock, flags);
#define READ_COND (!list_empty(&hidg->completed_out_req))
/* wait for at least one buffer to complete */
while (!READ_COND) {
- spin_unlock_irqrestore(&hidg->spinlock, flags);
+ spin_unlock_irqrestore(&hidg->read_spinlock, flags);
if (file->f_flags & O_NONBLOCK)
return -EAGAIN;
if (wait_event_interruptible(hidg->read_queue, READ_COND))
return -ERESTARTSYS;
- spin_lock_irqsave(&hidg->spinlock, flags);
+ spin_lock_irqsave(&hidg->read_spinlock, flags);
}
/* pick the first one */
@@ -206,7 +206,7 @@ static ssize_t f_hidg_read(struct file *
req = list->req;
count = min_t(unsigned int, count, req->actual - list->pos);
- spin_unlock_irqrestore(&hidg->spinlock, flags);
+ spin_unlock_irqrestore(&hidg->read_spinlock, flags);
/* copy to user outside spinlock */
count -= copy_to_user(buffer, req->buf + list->pos, count);
@@ -228,9 +228,9 @@ static ssize_t f_hidg_read(struct file *
return ret;
}
} else {
- spin_lock_irqsave(&hidg->spinlock, flags);
+ spin_lock_irqsave(&hidg->read_spinlock, flags);
list_add(&list->list, &hidg->completed_out_req);
- spin_unlock_irqrestore(&hidg->spinlock, flags);
+ spin_unlock_irqrestore(&hidg->read_spinlock, flags);
wake_up(&hidg->read_queue);
}
@@ -241,13 +241,16 @@ static ssize_t f_hidg_read(struct file *
static void f_hidg_req_complete(struct usb_ep *ep, struct usb_request *req)
{
struct f_hidg *hidg = (struct f_hidg *)ep->driver_data;
+ unsigned long flags;
if (req->status != 0) {
ERROR(hidg->func.config->cdev,
"End Point Request ERROR: %d\n", req->status);
}
+ spin_lock_irqsave(&hidg->write_spinlock, flags);
hidg->write_pending = 0;
+ spin_unlock_irqrestore(&hidg->write_spinlock, flags);
wake_up(&hidg->write_queue);
}
@@ -255,18 +258,19 @@ static ssize_t f_hidg_write(struct file
size_t count, loff_t *offp)
{
struct f_hidg *hidg = file->private_data;
+ unsigned long flags;
ssize_t status = -ENOMEM;
if (!access_ok(VERIFY_READ, buffer, count))
return -EFAULT;
- mutex_lock(&hidg->lock);
+ spin_lock_irqsave(&hidg->write_spinlock, flags);
#define WRITE_COND (!hidg->write_pending)
/* write queue */
while (!WRITE_COND) {
- mutex_unlock(&hidg->lock);
+ spin_unlock_irqrestore(&hidg->write_spinlock, flags);
if (file->f_flags & O_NONBLOCK)
return -EAGAIN;
@@ -274,17 +278,20 @@ static ssize_t f_hidg_write(struct file
hidg->write_queue, WRITE_COND))
return -ERESTARTSYS;
- mutex_lock(&hidg->lock);
+ spin_lock_irqsave(&hidg->write_spinlock, flags);
}
+ hidg->write_pending = 1;
count = min_t(unsigned, count, hidg->report_length);
+
+ spin_unlock_irqrestore(&hidg->write_spinlock, flags);
status = copy_from_user(hidg->req->buf, buffer, count);
if (status != 0) {
ERROR(hidg->func.config->cdev,
"copy_from_user error\n");
- mutex_unlock(&hidg->lock);
- return -EINVAL;
+ status = -EINVAL;
+ goto release_write_pending;
}
hidg->req->status = 0;
@@ -292,19 +299,23 @@ static ssize_t f_hidg_write(struct file
hidg->req->length = count;
hidg->req->complete = f_hidg_req_complete;
hidg->req->context = hidg;
- hidg->write_pending = 1;
status = usb_ep_queue(hidg->in_ep, hidg->req, GFP_ATOMIC);
if (status < 0) {
ERROR(hidg->func.config->cdev,
"usb_ep_queue error on int endpoint %zd\n", status);
- hidg->write_pending = 0;
- wake_up(&hidg->write_queue);
+ goto release_write_pending;
} else {
status = count;
}
- mutex_unlock(&hidg->lock);
+ return status;
+release_write_pending:
+ spin_lock_irqsave(&hidg->write_spinlock, flags);
+ hidg->write_pending = 0;
+ spin_unlock_irqrestore(&hidg->write_spinlock, flags);
+
+ wake_up(&hidg->write_queue);
return status;
}
@@ -371,9 +382,9 @@ static void hidg_set_report_complete(str
req_list->req = req;
- spin_lock_irqsave(&hidg->spinlock, flags);
+ spin_lock_irqsave(&hidg->read_spinlock, flags);
list_add_tail(&req_list->list, &hidg->completed_out_req);
- spin_unlock_irqrestore(&hidg->spinlock, flags);
+ spin_unlock_irqrestore(&hidg->read_spinlock, flags);
wake_up(&hidg->read_queue);
break;
@@ -491,13 +502,13 @@ static void hidg_disable(struct usb_func
usb_ep_disable(hidg->out_ep);
hidg->out_ep->driver_data = NULL;
- spin_lock_irqsave(&hidg->spinlock, flags);
+ spin_lock_irqsave(&hidg->read_spinlock, flags);
list_for_each_entry_safe(list, next, &hidg->completed_out_req, list) {
free_ep_req(hidg->out_ep, list->req);
list_del(&list->list);
kfree(list);
}
- spin_unlock_irqrestore(&hidg->spinlock, flags);
+ spin_unlock_irqrestore(&hidg->read_spinlock, flags);
}
static int hidg_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
@@ -642,8 +653,8 @@ static int __init hidg_bind(struct usb_c
if (status)
goto fail;
- mutex_init(&hidg->lock);
- spin_lock_init(&hidg->spinlock);
+ spin_lock_init(&hidg->write_spinlock);
+ spin_lock_init(&hidg->read_spinlock);
init_waitqueue_head(&hidg->write_queue);
init_waitqueue_head(&hidg->read_queue);
INIT_LIST_HEAD(&hidg->completed_out_req);
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