Re: [PATCH] pinctrl: qcom: Don't lock around irq_set_irq_wake()

[Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>]

On Tue 21 Jan 10:09 PST 2020, Stephen Boyd wrote:

> We don't need to hold the local pinctrl lock here to set irq wake on the
> summary irq line. Doing so only leads to lockdep warnings instead of
> protecting us from anything. Remove the locking.
> 
>  WARNING: possible circular locking dependency detected
>  5.4.11 #2 Tainted: G        W
>  ------------------------------------------------------
>  cat/3083 is trying to acquire lock:
>  ffffff81f4fa58c0 (&irq_desc_lock_class){-.-.}, at: __irq_get_desc_lock+0x64/0x94
> 
>  but task is already holding lock:
>  ffffff81f4880c18 (&pctrl->lock){-.-.}, at: msm_gpio_irq_set_wake+0x48/0x7c
> 
>  which lock already depends on the new lock.
> 
>  the existing dependency chain (in reverse order) is:
> 
>  -> #1 (&pctrl->lock){-.-.}:
>         _raw_spin_lock_irqsave+0x64/0x80
>         msm_gpio_irq_ack+0x68/0xf4
>         __irq_do_set_handler+0xe0/0x180
>         __irq_set_handler+0x60/0x9c
>         irq_domain_set_info+0x90/0xb4
>         gpiochip_hierarchy_irq_domain_alloc+0x110/0x200
>         __irq_domain_alloc_irqs+0x130/0x29c
>         irq_create_fwspec_mapping+0x1f0/0x300
>         irq_create_of_mapping+0x70/0x98
>         of_irq_get+0xa4/0xd4
>         spi_drv_probe+0x4c/0xb0
>         really_probe+0x138/0x3f0
>         driver_probe_device+0x70/0x140
>         __device_attach_driver+0x9c/0x110
>         bus_for_each_drv+0x88/0xd0
>         __device_attach+0xb0/0x160
>         device_initial_probe+0x20/0x2c
>         bus_probe_device+0x34/0x94
>         device_add+0x35c/0x3f0
>         spi_add_device+0xbc/0x194
>         of_register_spi_devices+0x2c8/0x408
>         spi_register_controller+0x57c/0x6fc
>         spi_geni_probe+0x260/0x328
>         platform_drv_probe+0x90/0xb0
>         really_probe+0x138/0x3f0
>         driver_probe_device+0x70/0x140
>         device_driver_attach+0x4c/0x6c
>         __driver_attach+0xcc/0x154
>         bus_for_each_dev+0x84/0xcc
>         driver_attach+0x2c/0x38
>         bus_add_driver+0x108/0x1fc
>         driver_register+0x64/0xf8
>         __platform_driver_register+0x4c/0x58
>         spi_geni_driver_init+0x1c/0x24
>         do_one_initcall+0x1a4/0x3e8
>         do_initcall_level+0xb4/0xcc
>         do_basic_setup+0x30/0x48
>         kernel_init_freeable+0x124/0x1a8
>         kernel_init+0x14/0x100
>         ret_from_fork+0x10/0x18
> 
>  -> #0 (&irq_desc_lock_class){-.-.}:
>         __lock_acquire+0xeb4/0x2388
>         lock_acquire+0x1cc/0x210
>         _raw_spin_lock_irqsave+0x64/0x80
>         __irq_get_desc_lock+0x64/0x94
>         irq_set_irq_wake+0x40/0x144
>         msm_gpio_irq_set_wake+0x5c/0x7c
>         set_irq_wake_real+0x40/0x5c
>         irq_set_irq_wake+0x70/0x144
>         cros_ec_rtc_suspend+0x38/0x4c
>         platform_pm_suspend+0x34/0x60
>         dpm_run_callback+0x64/0xcc
>         __device_suspend+0x310/0x41c
>         dpm_suspend+0xf8/0x298
>         dpm_suspend_start+0x84/0xb4
>         suspend_devices_and_enter+0xbc/0x620
>         pm_suspend+0x210/0x348
>         state_store+0xb0/0x108
>         kobj_attr_store+0x14/0x24
>         sysfs_kf_write+0x4c/0x64
>         kernfs_fop_write+0x15c/0x1fc
>         __vfs_write+0x54/0x18c
>         vfs_write+0xe4/0x1a4
>         ksys_write+0x7c/0xe4
>         __arm64_sys_write+0x20/0x2c
>         el0_svc_common+0xa8/0x160
>         el0_svc_handler+0x7c/0x98
>         el0_svc+0x8/0xc
> 
>  other info that might help us debug this:
> 
>   Possible unsafe locking scenario:
> 
>         CPU0                    CPU1
>         ----                    ----
>    lock(&pctrl->lock);
>                                 lock(&irq_desc_lock_class);
>                                 lock(&pctrl->lock);
>    lock(&irq_desc_lock_class);
> 
>   *** DEADLOCK ***
> 
>  7 locks held by cat/3083:
>   #0: ffffff81f06d1420 (sb_writers#7){.+.+}, at: vfs_write+0xd0/0x1a4
>   #1: ffffff81c8935680 (&of->mutex){+.+.}, at: kernfs_fop_write+0x12c/0x1fc
>   #2: ffffff81f4c322f0 (kn->count#337){.+.+}, at: kernfs_fop_write+0x134/0x1fc
>   #3: ffffffe89a641d60 (system_transition_mutex){+.+.}, at: pm_suspend+0x108/0x348
>   #4: ffffff81f190e970 (&dev->mutex){....}, at: __device_suspend+0x168/0x41c
>   #5: ffffff81f183d8c0 (lock_class){-.-.}, at: __irq_get_desc_lock+0x64/0x94
>   #6: ffffff81f4880c18 (&pctrl->lock){-.-.}, at: msm_gpio_irq_set_wake+0x48/0x7c
> 
>  stack backtrace:
>  CPU: 4 PID: 3083 Comm: cat Tainted: G        W         5.4.11 #2
>  Hardware name: Google Cheza (rev3+) (DT)
>  Call trace:
>   dump_backtrace+0x0/0x174
>   show_stack+0x20/0x2c
>   dump_stack+0xc8/0x124
>   print_circular_bug+0x2ac/0x2c4
>   check_noncircular+0x1a0/0x1a8
>   __lock_acquire+0xeb4/0x2388
>   lock_acquire+0x1cc/0x210
>   _raw_spin_lock_irqsave+0x64/0x80
>   __irq_get_desc_lock+0x64/0x94
>   irq_set_irq_wake+0x40/0x144
>   msm_gpio_irq_set_wake+0x5c/0x7c
>   set_irq_wake_real+0x40/0x5c
>   irq_set_irq_wake+0x70/0x144
>   cros_ec_rtc_suspend+0x38/0x4c
>   platform_pm_suspend+0x34/0x60
>   dpm_run_callback+0x64/0xcc
>   __device_suspend+0x310/0x41c
>   dpm_suspend+0xf8/0x298
>   dpm_suspend_start+0x84/0xb4
>   suspend_devices_and_enter+0xbc/0x620
>   pm_suspend+0x210/0x348
>   state_store+0xb0/0x108
>   kobj_attr_store+0x14/0x24
>   sysfs_kf_write+0x4c/0x64
>   kernfs_fop_write+0x15c/0x1fc
>   __vfs_write+0x54/0x18c
>   vfs_write+0xe4/0x1a4
>   ksys_write+0x7c/0xe4
>   __arm64_sys_write+0x20/0x2c
>   el0_svc_common+0xa8/0x160
>   el0_svc_handler+0x7c/0x98
>   el0_svc+0x8/0xc
> 
> Fixes: f365be092572 ("pinctrl: Add Qualcomm TLMM driver")

This lock used to protect the wake_irqs bitmap, and although your change
indicates that the locking was wrong before this point I think the fixes
should be:

Fixes: 6aced33f4974 ("pinctrl: msm: drop wake_irqs bitmap")


Either way, the patch looks good.

Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>

Thanks,
Bjorn

> Cc: Douglas Anderson <dianders@xxxxxxxxxxxx>
> Cc: Brian Masney <masneyb@xxxxxxxxxxxxx>
> Cc: Lina Iyer <ilina@xxxxxxxxxxxxxx>
> Cc: Maulik Shah <mkshah@xxxxxxxxxxxxxx>
> Cc: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
> ---
>  drivers/pinctrl/qcom/pinctrl-msm.c | 5 -----
>  1 file changed, 5 deletions(-)
> 
> diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
> index 5d6f9f61ce02..9a8daa256a32 100644
> --- a/drivers/pinctrl/qcom/pinctrl-msm.c
> +++ b/drivers/pinctrl/qcom/pinctrl-msm.c
> @@ -960,7 +960,6 @@ static int msm_gpio_irq_set_wake(struct irq_data *d, unsigned int on)
>  {
>  	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
>  	struct msm_pinctrl *pctrl = gpiochip_get_data(gc);
> -	unsigned long flags;
>  
>  	/*
>  	 * While they may not wake up when the TLMM is powered off,
> @@ -971,12 +970,8 @@ static int msm_gpio_irq_set_wake(struct irq_data *d, unsigned int on)
>  	if (d->parent_data)
>  		irq_chip_set_wake_parent(d, on);
>  
> -	raw_spin_lock_irqsave(&pctrl->lock, flags);
> -
>  	irq_set_irq_wake(pctrl->irq, on);
>  
> -	raw_spin_unlock_irqrestore(&pctrl->lock, flags);
> -
>  	return 0;
>  }
>  
> -- 
> Sent by a computer, using git, on the internet
>