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Subject[tip: locking/core] usb: gadget: Use completion interface instead of open coding it
The following commit has been merged into the locking/core branch of tip:

Commit-ID: c1d51dd505577b189bf33867a9c20015ca7efb46
Gitweb: https://git.kernel.org/tip/c1d51dd505577b189bf33867a9c20015ca7efb46
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Sat, 21 Mar 2020 12:25:47 +01:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Sat, 21 Mar 2020 16:00:20 +01:00

usb: gadget: Use completion interface instead of open coding it

ep_io() uses a completion on stack and open codes the waiting with:

wait_event_interruptible (done.wait, done.done);
and
wait_event (done.wait, done.done);

This waits in non-exclusive mode for complete(), but there is no reason to
do so because the completion can only be waited for by the task itself and
complete() wakes exactly one exlusive waiter.

Replace the open coded implementation with the corresponding
wait_for_completion*() functions.

No functional change.

Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lkml.kernel.org/r/20200321113241.043380271@linutronix.de
---
drivers/usb/gadget/legacy/inode.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
index b47938d..4c3aff9 100644
--- a/drivers/usb/gadget/legacy/inode.c
+++ b/drivers/usb/gadget/legacy/inode.c
@@ -344,7 +344,7 @@ ep_io (struct ep_data *epdata, void *buf, unsigned len)
spin_unlock_irq (&epdata->dev->lock);

if (likely (value == 0)) {
- value = wait_event_interruptible (done.wait, done.done);
+ value = wait_for_completion_interruptible(&done);
if (value != 0) {
spin_lock_irq (&epdata->dev->lock);
if (likely (epdata->ep != NULL)) {
@@ -353,7 +353,7 @@ ep_io (struct ep_data *epdata, void *buf, unsigned len)
usb_ep_dequeue (epdata->ep, epdata->req);
spin_unlock_irq (&epdata->dev->lock);

- wait_event (done.wait, done.done);
+ wait_for_completion(&done);
if (epdata->status == -ECONNRESET)
epdata->status = -EINTR;
} else {
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