Re: [PATCH 1/4] PCI: imx6: Mark the msi cascade handler IRQF_NO_THREAD

[Lucas Stach <l.stach@pengutronix.de>]

Hi Kevin,

Am Freitag, den 24.07.2015, 13:29 +0800 schrieb Kevin Hao:
> The cascade handler must run in hard interrupt context, otherwise
> it will cause the following kernel warning if we force threading
> of all the interrupt handlers via kernel command parameter
> "threadirqs":

The change looks good, but there are a few other designware drivers that
use the same logic to trigger the cascaded MSI handler. Can you please
make sure to change them, too?

Regards,
Lucas

>    [ INFO: inconsistent lock state ]
>    4.2.0-rc3-next-20150723 #28 Not tainted
>    ---------------------------------
>    inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
>    irq/21-mx6-pcie/62 [HC0[0]:SC0[2]:HE1:SE0] takes:
>     (&irq_desc_lock_class){?.-...}, at: [<80078d94>] handle_simple_irq+0x1c/0xc0
>    {IN-HARDIRQ-W} state was registered at:
>      [<8006aa70>] lock_acquire+0x74/0x94
>      [<807acc6c>] _raw_spin_lock+0x34/0x44
>      [<8007900c>] handle_fasteoi_irq+0x20/0x1b8
>      [<80075720>] generic_handle_irq+0x28/0x38
>      [<80075864>] __handle_domain_irq+0x6c/0xe0
>      [<80009558>] gic_handle_irq+0x28/0x68
>      [<80013b64>] __irq_svc+0x44/0x5c
>      [<807ad400>] _raw_spin_unlock_irq+0x30/0x34
>      [<8004cffc>] finish_task_switch+0xc0/0x218
>      [<807a7a10>] __schedule+0x248/0x6e0
>      [<807a7fac>] schedule+0x38/0x9c
>      [<807a8240>] schedule_preempt_disabled+0x10/0x14
>      [<80063f8c>] cpu_startup_entry+0xfc/0x1f8
>      [<8079f640>] rest_init+0x130/0x16c
>      [<80a55ca4>] start_kernel+0x374/0x3e8
>      [<1000807c>] 0x1000807c
>    irq event stamp: 16
>    hardirqs last  enabled at (15): [<807ad3fc>] _raw_spin_unlock_irq+0x2c/0x34
>    hardirqs last disabled at (14): [<807acd80>] _raw_spin_lock_irq+0x20/0x58
>    softirqs last  enabled at (0): [<800283d8>] copy_process.isra.58+0x3bc/0x1504
>    softirqs last disabled at (16): [<80076f08>] irq_forced_thread_fn+0x0/0x68
> 
>    other info that might help us debug this:
>     Possible unsafe locking scenario:
> 
>           CPU0
>           ----
>      lock(&irq_desc_lock_class);
>      <Interrupt>
>        lock(&irq_desc_lock_class);
> 
>     *** DEADLOCK ***
> 
>    no locks held by irq/21-mx6-pcie/62.
> 
>    stack backtrace:
>    CPU: 0 PID: 62 Comm: irq/21-mx6-pcie Not tainted 4.2.0-rc3-next-20150723 #28
>    Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
>    Backtrace:
>    [<80012dc4>] (dump_backtrace) from [<80012f64>] (show_stack+0x18/0x1c)
>     r6:be3eeb78 r5:00000000 r4:00000000 r3:00000000
>    [<80012f4c>] (show_stack) from [<807a4b50>] (dump_stack+0x80/0x9c)
>    [<807a4ad0>] (dump_stack) from [<807a2efc>] (print_usage_bug+0x270/0x2e4)
>     r5:be3ee780 r4:80c579ec
>    [<807a2c8c>] (print_usage_bug) from [<8006874c>] (mark_lock+0x5b4/0x6e0)
>     r10:80c579ec r9:800678e0 r8:be3ee780 r7:00000000 r6:80c579ec r5:be3eeb78
>     r4:00000002
>    [<80068198>] (mark_lock) from [<80068f70>] (__lock_acquire+0x6f8/0x1e20)
>     r10:00000001 r9:be3eeb78 r8:be3ee780 r7:00000008 r6:000003f8 r5:be3ee780
>     r4:00000000
>    [<80068878>] (__lock_acquire) from [<8006aa70>] (lock_acquire+0x74/0x94)
>     r10:00000001 r9:00000001 r8:00000000 r7:00000001 r6:00000001 r5:60030013
>     r4:00000000
>    [<8006a9fc>] (lock_acquire) from [<807acc6c>] (_raw_spin_lock+0x34/0x44)
>     r6:0000012c r5:00000001 r4:be1f4d64
>    [<807acc38>] (_raw_spin_lock) from [<80078d94>] (handle_simple_irq+0x1c/0xc0)
>     r5:be1f4d64 r4:be1f4d00
>    [<80078d78>] (handle_simple_irq) from [<80075720>] (generic_handle_irq+0x28/0x38)
>     r5:be28ee20 r4:0000012c
>    [<800756f8>] (generic_handle_irq) from [<80321914>] (dw_handle_msi_irq+0x68/0x90)
>     r4:00000001 r3:00000002
>    [<803218ac>] (dw_handle_msi_irq) from [<8032265c>] (imx6_pcie_msi_handler+0x14/0x18)
>     r7:80076f08 r6:be39efc0 r5:be154000 r4:be39efc0
>    [<80322648>] (imx6_pcie_msi_handler) from [<80076f38>] (irq_forced_thread_fn+0x30/0x68)
>    [<80076f08>] (irq_forced_thread_fn) from [<80076cb4>] (irq_thread+0x14c/0x19c)
>     r6:be39efc0 r5:be154000 r4:be39efe0 r3:00000004
>    [<80076b68>] (irq_thread) from [<80047f80>] (kthread+0xdc/0xf8)
>     r10:00000000 r9:00000000 r8:00000000 r7:80076b68 r6:be39efc0 r5:be3a1000
>     r4:00000000
>    [<80047ea4>] (kthread) from [<8000fa38>] (ret_from_fork+0x14/0x3c)
>     r7:00000000 r6:00000000 r5:80047ea4 r4:be3a1000
> 
> Signed-off-by: Kevin Hao <haokexin@gmail.com>
> ---
>  drivers/pci/host/pci-imx6.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
> index 233a196c6e66..fd5eb2e34fc0 100644
> --- a/drivers/pci/host/pci-imx6.c
> +++ b/drivers/pci/host/pci-imx6.c
> @@ -544,7 +544,8 @@ static int __init imx6_add_pcie_port(struct pcie_port *pp,
>  
>  		ret = devm_request_irq(&pdev->dev, pp->msi_irq,
>  				       imx6_pcie_msi_handler,
> -				       IRQF_SHARED, "mx6-pcie-msi", pp);
> +				       IRQF_SHARED | IRQF_NO_THREAD,
> +				       "mx6-pcie-msi", pp);
>  		if (ret) {
>  			dev_err(&pdev->dev, "failed to request MSI irq\n");
>  			return -ENODEV;

-- 
Pengutronix e.K.             | Lucas Stach                 |
Industrial Linux Solutions   | http://www.pengutronix.de/  |