This is a note to let you know that I've just added the patch titled phy: sun4i-usb: Use spinlock to guard phyctl register access to the 4.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: phy-sun4i-usb-use-spinlock-to-guard-phyctl-register-access.patch and it can be found in the queue-4.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 919ab2524c52e5f801d8873f09145ce822cdd43a Mon Sep 17 00:00:00 2001 From: Chen-Yu Tsai <wens@xxxxxxxx> Date: Fri, 9 Sep 2016 11:58:18 +0800 Subject: phy: sun4i-usb: Use spinlock to guard phyctl register access From: Chen-Yu Tsai <wens@xxxxxxxx> commit 919ab2524c52e5f801d8873f09145ce822cdd43a upstream. The musb driver calls into this phy driver to disable/enable squelch detection. This function was introduced in 24fe86a617c5 ("phy: sun4i-usb: Add a sunxi specific function for setting squelch-detect"). This function in turn calls sun4i_usb_phy_write, which uses a mutex to guard the common access register. Unfortunately musb does this in atomic context, which results in the following warning with lock debugging enabled: BUG: sleeping function called from invalid context at kernel/locking/mutex.c:97 in_atomic(): 1, irqs_disabled(): 128, pid: 96, name: kworker/0:2 CPU: 0 PID: 96 Comm: kworker/0:2 Not tainted 4.8.0-rc4-00181-gd502f8ad1c3e #13 Hardware name: Allwinner sun8i Family Workqueue: events musb_deassert_reset [<c010bc01>] (unwind_backtrace) from [<c0109237>] (show_stack+0xb/0xc) [<c0109237>] (show_stack) from [<c02a669b>] (dump_stack+0x67/0x74) [<c02a669b>] (dump_stack) from [<c05d68c9>] (mutex_lock+0x15/0x2c) [<c05d68c9>] (mutex_lock) from [<c02c3589>] (sun4i_usb_phy_write+0x39/0xec) [<c02c3589>] (sun4i_usb_phy_write) from [<c03e6327>] (musb_port_reset+0xfb/0x184) [<c03e6327>] (musb_port_reset) from [<c03e4917>] (musb_deassert_reset+0x1f/0x2c) [<c03e4917>] (musb_deassert_reset) from [<c012ecb5>] (process_one_work+0x129/0x2b8) [<c012ecb5>] (process_one_work) from [<c012f5e3>] (worker_thread+0xf3/0x424) [<c012f5e3>] (worker_thread) from [<c0132dbd>] (kthread+0xa1/0xb8) [<c0132dbd>] (kthread) from [<c0105f31>] (ret_from_fork+0x11/0x20) Since the register access is mmio, we can use a spinlock to guard this specific access, rather than the mutex that guards the entire phy. Fixes: ba4bdc9e1dc0 ("PHY: sunxi: Add driver for sunxi usb phy") Cc: Hans de Goede <hdegoede@xxxxxxxxxx> Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx> Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/phy/phy-sun4i-usb.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) --- a/drivers/phy/phy-sun4i-usb.c +++ b/drivers/phy/phy-sun4i-usb.c @@ -40,6 +40,7 @@ #include <linux/power_supply.h> #include <linux/regulator/consumer.h> #include <linux/reset.h> +#include <linux/spinlock.h> #include <linux/usb/of.h> #include <linux/workqueue.h> @@ -112,7 +113,7 @@ struct sun4i_usb_phy_data { void __iomem *base; const struct sun4i_usb_phy_cfg *cfg; enum usb_dr_mode dr_mode; - struct mutex mutex; + spinlock_t reg_lock; /* guard access to phyctl reg */ struct sun4i_usb_phy { struct phy *phy; void __iomem *pmu; @@ -179,9 +180,10 @@ static void sun4i_usb_phy_write(struct s struct sun4i_usb_phy_data *phy_data = to_sun4i_usb_phy_data(phy); u32 temp, usbc_bit = BIT(phy->index * 2); void __iomem *phyctl = phy_data->base + phy_data->cfg->phyctl_offset; + unsigned long flags; int i; - mutex_lock(&phy_data->mutex); + spin_lock_irqsave(&phy_data->reg_lock, flags); if (phy_data->cfg->type == sun8i_a33_phy) { /* A33 needs us to set phyctl to 0 explicitly */ @@ -218,7 +220,8 @@ static void sun4i_usb_phy_write(struct s data >>= 1; } - mutex_unlock(&phy_data->mutex); + + spin_unlock_irqrestore(&phy_data->reg_lock, flags); } static void sun4i_usb_phy_passby(struct sun4i_usb_phy *phy, int enable) @@ -577,7 +580,7 @@ static int sun4i_usb_phy_probe(struct pl if (!data) return -ENOMEM; - mutex_init(&data->mutex); + spin_lock_init(&data->reg_lock); INIT_DELAYED_WORK(&data->detect, sun4i_usb_phy0_id_vbus_det_scan); dev_set_drvdata(dev, data); data->cfg = of_device_get_match_data(dev); Patches currently in stable-queue which might be from wens@xxxxxxxx are queue-4.8/phy-sun4i-usb-use-spinlock-to-guard-phyctl-register-access.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html