musb_queue_resume_work() would call the provided callback if the runtime PM status was 'active'. Otherwise, it would enqueue the request if the hardware was still suspended (musb->is_runtime_suspended is true).
This causes a race with the runtime PM handlers, as it is possible to be in the case where the runtime PM status is not yet 'active', but the hardware has been awaken (PM resume function has been called).
When hitting the race, the resume work was not enqueued, which probably triggered other bugs further down the stack. For instance, a telnet connection on Ingenic SoCs would result in a 50/50 chance of a segmentation fault somewhere in the musb code.
Rework the code so that either we call the callback directly if (musb->is_runtime_suspended == 0), or enqueue the query otherwise.
Fixes: ea2f35c01d5e ("usb: musb: Fix sleeping function called from invalid context for hdrc glue") Cc: stable@vger.kernel.org # v4.9 Signed-off-by: Paul Cercueil paul@crapouillou.net --- drivers/usb/musb/musb_core.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c index 384a8039a7fd..462c10d7455a 100644 --- a/drivers/usb/musb/musb_core.c +++ b/drivers/usb/musb/musb_core.c @@ -2241,32 +2241,35 @@ int musb_queue_resume_work(struct musb *musb, { struct musb_pending_work *w; unsigned long flags; + bool is_suspended; int error;
if (WARN_ON(!callback)) return -EINVAL;
- if (pm_runtime_active(musb->controller)) - return callback(musb, data); + spin_lock_irqsave(&musb->list_lock, flags); + is_suspended = musb->is_runtime_suspended; + + if (is_suspended) { + w = devm_kzalloc(musb->controller, sizeof(*w), GFP_ATOMIC); + if (!w) { + error = -ENOMEM; + goto out_unlock; + }
- w = devm_kzalloc(musb->controller, sizeof(*w), GFP_ATOMIC); - if (!w) - return -ENOMEM; + w->callback = callback; + w->data = data;
- w->callback = callback; - w->data = data; - spin_lock_irqsave(&musb->list_lock, flags); - if (musb->is_runtime_suspended) { list_add_tail(&w->node, &musb->pending_list); error = 0; - } else { - dev_err(musb->controller, "could not add resume work %p\n", - callback); - devm_kfree(musb->controller, w); - error = -EINPROGRESS; } + +out_unlock: spin_unlock_irqrestore(&musb->list_lock, flags);
+ if (!is_suspended) + error = callback(musb, data); + return error; } EXPORT_SYMBOL_GPL(musb_queue_resume_work);