On Thu, Oct 27, 2016 at 08:14:46AM -0700, Tony Lindgren wrote:
> * Tony Lindgren <tony@xxxxxxxxxxx> [161026 07:32]:
> 8< -------------------------------
> From tony Mon Sep 17 00:00:00 2001
> From: Tony Lindgren <tony@xxxxxxxxxxx>
> Date: Tue, 25 Oct 2016 08:42:00 -0700
> Subject: [PATCH] usb: musb: Fix sleeping function called from invalid
> context for hdrc glue
>
> Commit 65b3f50ed6fa ("usb: musb: Add PM runtime support for MUSB DSPS
> glue layer") wrongly added a call for pm_runtime_get_sync to otg_timer
> that runs in softirq context. That causes a "BUG: sleeping function called
> from invalid context" every time when polling the cable status:
>
> [<c015ebb4>] (__might_sleep) from [<c0413d60>] (__pm_runtime_resume+0x9c/0xa0)
> [<c0413d60>] (__pm_runtime_resume) from [<c04d0bc4>] (otg_timer+0x3c/0x254)
> [<c04d0bc4>] (otg_timer) from [<c0191180>] (call_timer_fn+0xfc/0x41c)
> [<c0191180>] (call_timer_fn) from [<c01915c0>] (expire_timers+0x120/0x210)
> [<c01915c0>] (expire_timers) from [<c0191acc>] (run_timer_softirq+0xa4/0xdc)
> [<c0191acc>] (run_timer_softirq) from [<c010168c>] (__do_softirq+0x12c/0x594)
>
> I did not notice that as I did not have CONFIG_DEBUG_ATOMIC_SLEEP enabled.
>
> Let's fix the issue by adding dsps_check_status() and then register a
> callback with musb_runtime_resume() so it gets called only when musb core
> and it's parent devices are awake. Note that we don't want to do this from
> PM runtime resume in musb_dsps.c as musb core is not awake yet at that
> point as noted by Johan Hovold <johan@xxxxxxxxxx>.
It seems some chunks are missing since this patch only runs the
deferred work at remove and not at runtime resume, effectively breaking
detection.
> Note that musb_gadget_queue() also suffers from a similar issue when
> connecting the cable and cannot use pm_runtime_get_sync().
You seem to have left that pm_runtime_get_sync() in there though.
> Fixes: 65b3f50ed6fa ("usb: musb: Add PM runtime support for MUSB DSPS
> glue layer")
> Reported-by: Johan Hovold <johan@xxxxxxxxxx>
> Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
> ---
> drivers/usb/musb/musb_core.c | 44 +++++++++++++++++++++++++++++++++++++++++-
> drivers/usb/musb/musb_core.h | 7 +++++++
> drivers/usb/musb/musb_dsps.c | 29 +++++++++++++++++++++-------
> drivers/usb/musb/musb_gadget.c | 16 +++++++++++++--
> 4 files changed, 86 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
> --- a/drivers/usb/musb/musb_core.c
> +++ b/drivers/usb/musb/musb_core.c
> @@ -122,7 +122,6 @@ MODULE_AUTHOR(DRIVER_AUTHOR);
> MODULE_LICENSE("GPL");
> MODULE_ALIAS("platform:" MUSB_DRIVER_NAME);
>
> -
> /*-------------------------------------------------------------------------*/
>
> static inline struct musb *dev_to_musb(struct device *dev)
> @@ -1896,6 +1895,46 @@ static void musb_pm_runtime_check_session(struct musb *musb)
> musb->session = s;
> }
>
> +struct musb_resume_work {
> + void (*callback)(struct musb *musb, void *data);
> + void *data;
> + struct list_head node;
> +};
> +
> +void musb_queue_on_resume(struct musb *musb,
> + void (*callback)(struct musb *musb, void *data),
> + void *data)
> +{
> + struct musb_resume_work *w;
> + unsigned long flags;
> +
> + w = devm_kzalloc(musb->controller, sizeof(*w), GFP_ATOMIC);
> + if (!w)
> + return;
> +
> + w->callback = callback;
> + w->data = data;
> + spin_lock_irqsave(&musb->list_lock, flags);
> + list_add_tail(&w->node, &musb->resume_work);
> + spin_unlock_irqrestore(&musb->list_lock, flags);
> +}
> +EXPORT_SYMBOL_GPL(musb_queue_on_resume);
> +
> +static void musb_run_pending(struct musb *musb)
> +{
> + struct musb_resume_work *w, *_w;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&musb->list_lock, flags);
> + list_for_each_entry_safe(w, _w, &musb->resume_work, node) {
> + if (w->callback)
> + w->callback(musb, w->data);
> + list_del(&w->node);
> + devm_kfree(musb->controller, w);
> + }
> + spin_unlock_irqrestore(&musb->list_lock, flags);
> +}
> +
> /* Only used to provide driver mode change events */
> static void musb_irq_work(struct work_struct *data)
> {
> @@ -1969,6 +2008,7 @@ static struct musb *allocate_instance(struct device *dev,
> INIT_LIST_HEAD(&musb->control);
> INIT_LIST_HEAD(&musb->in_bulk);
> INIT_LIST_HEAD(&musb->out_bulk);
> + INIT_LIST_HEAD(&musb->resume_work);
>
> musb->vbuserr_retry = VBUSERR_RETRY_COUNT;
> musb->a_wait_bcon = OTG_TIME_A_WAIT_BCON;
> @@ -2065,6 +2105,7 @@ musb_init_controller(struct device *dev, int nIrq, void __iomem *ctrl)
> }
>
> spin_lock_init(&musb->lock);
> + spin_lock_init(&musb->list_lock);
> musb->board_set_power = plat->set_power;
> musb->min_power = plat->min_power;
> musb->ops = plat->platform_ops;
> @@ -2374,6 +2415,7 @@ static int musb_remove(struct platform_device *pdev)
> * - Peripheral mode: peripheral is deactivated (or never-activated)
> * - OTG mode: both roles are deactivated (or never-activated)
> */
> + musb_run_pending(musb);
> musb_exit_debugfs(musb);
>
> cancel_work_sync(&musb->irq_work);
> diff --git a/drivers/usb/musb/musb_core.h b/drivers/usb/musb/musb_core.h
> --- a/drivers/usb/musb/musb_core.h
> +++ b/drivers/usb/musb/musb_core.h
> @@ -303,6 +303,7 @@ struct musb_context_registers {
> struct musb {
> /* device lock */
> spinlock_t lock;
> + spinlock_t list_lock; /* resume work list lock */
>
> struct musb_io io;
> const struct musb_platform_ops *ops;
> @@ -337,6 +338,7 @@ struct musb {
> struct list_head control; /* of musb_qh */
> struct list_head in_bulk; /* of musb_qh */
> struct list_head out_bulk; /* of musb_qh */
> + struct list_head resume_work; /* pending work on resume */
>
> struct timer_list otg_timer;
> struct notifier_block nb;
> @@ -540,6 +542,11 @@ extern irqreturn_t musb_interrupt(struct musb *);
>
> extern void musb_hnp_stop(struct musb *musb);
>
> +extern void
> +musb_queue_on_resume(struct musb *musb,
> + void (*callback)(struct musb *musb, void *data),
> + void *data);
> +
> static inline void musb_platform_set_vbus(struct musb *musb, int is_on)
> {
> if (musb->ops->set_vbus)
> diff --git a/drivers/usb/musb/musb_dsps.c b/drivers/usb/musb/musb_dsps.c
> --- a/drivers/usb/musb/musb_dsps.c
> +++ b/drivers/usb/musb/musb_dsps.c
> @@ -188,9 +188,8 @@ static void dsps_musb_disable(struct musb *musb)
> musb_writeb(musb->mregs, MUSB_DEVCTL, 0);
> }
>
> -static void otg_timer(unsigned long _musb)
> +static void dsps_check_status(struct musb *musb)
> {
> - struct musb *musb = (void *)_musb;
> void __iomem *mregs = musb->mregs;
> struct device *dev = musb->controller;
> struct dsps_glue *glue = dev_get_drvdata(dev->parent);
> @@ -198,11 +197,6 @@ static void otg_timer(unsigned long _musb)
> u8 devctl;
> unsigned long flags;
> int skip_session = 0;
> - int err;
> -
> - err = pm_runtime_get_sync(dev);
> - if (err < 0)
> - dev_err(dev, "Poll could not pm_runtime_get: %i\n", err);
>
> /*
> * We poll because DSPS IP's won't expose several OTG-critical
> @@ -246,6 +240,27 @@ static void otg_timer(unsigned long _musb)
> break;
> }
> spin_unlock_irqrestore(&musb->lock, flags);
> +}
> +
> +static void dsps_check_status_resume_work(struct musb *musb, void *unused)
> +{
> + dsps_check_status(musb);
> +}
> +
> +static void otg_timer(unsigned long _musb)
> +{
> + struct musb *musb = (void *)_musb;
> + struct device *dev = musb->controller;
> + int err;
> +
> + err = pm_runtime_get(dev);
> + if (err < 0)
> + dev_err(dev, "Poll could not pm_runtime_get: %i\n", err);
> +
> + if (pm_runtime_active(dev))
> + dsps_check_status(musb);
> + else
> + musb_queue_on_resume(musb, dsps_check_status_resume_work, NULL);
>
> pm_runtime_mark_last_busy(dev);
> pm_runtime_put_autosuspend(dev);
> diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
> --- a/drivers/usb/musb/musb_gadget.c
> +++ b/drivers/usb/musb/musb_gadget.c
> @@ -1222,6 +1222,13 @@ void musb_ep_restart(struct musb *musb, struct musb_request *req)
> rxstate(musb, req);
> }
>
> +void musb_ep_restart_resume_work(struct musb *musb, void *data)
> +{
> + struct musb_request *req = data;
> +
> + musb_ep_restart(musb, req);
This one is supposed to be called with musb->lock held (according to the
function header anyway).
> +}
> +
> static int musb_gadget_queue(struct usb_ep *ep, struct usb_request *req,
> gfp_t gfp_flags)
> {
> @@ -1271,8 +1278,13 @@ static int musb_gadget_queue(struct usb_ep *ep, struct usb_request *req,
> list_add_tail(&request->list, &musb_ep->req_list);
>
> /* it this is the head of the queue, start i/o ... */
> - if (!musb_ep->busy && &request->list == musb_ep->req_list.next)
> - musb_ep_restart(musb, request);
> + if (!musb_ep->busy && &request->list == musb_ep->req_list.next) {
> + if (pm_runtime_active(musb->controller))
> + musb_ep_restart(musb, request);
> + else
> + musb_queue_on_resume(musb, musb_ep_restart_resume_work,
> + request);
> + }
>
> unlock:
> spin_unlock_irqrestore(&musb->lock, lockflags);
And then this looks like it could trigger an ABBA deadlock as musb->lock
is held while queue_on_resume() takes musb->list_lock, and
musb_run_pending() would take the same locks in the reverse order.
Johan
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