Re: [PATCH 1/1] ufs: core: fix &hwq->cq_lock deadlock issue

[Can Guo]

On 4/21/2023 3:56 PM, Alice Chao wrote:
> [name:lockdep&]WARNING: inconsistent lock state
> [name:lockdep&]--------------------------------
> [name:lockdep&]inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
> [name:lockdep&]kworker/u16:4/260 [HC0[0]:SC0[0]:HE1:SE1] takes:
>    ffffff8028444600 (&hwq->cq_lock){?.-.}-{2:2}, at:
> ufshcd_mcq_poll_cqe_lock+0x30/0xe0
> [name:lockdep&]{IN-HARDIRQ-W} state was registered at:
>    lock_acquire+0x17c/0x33c
>    _raw_spin_lock+0x5c/0x7c
>    ufshcd_mcq_poll_cqe_lock+0x30/0xe0
>    ufs_mtk_mcq_intr+0x60/0x1bc [ufs_mediatek_mod]
>    __handle_irq_event_percpu+0x140/0x3ec
>    handle_irq_event+0x50/0xd8
>    handle_fasteoi_irq+0x148/0x2b0
>    generic_handle_domain_irq+0x4c/0x6c
>    gic_handle_irq+0x58/0x134
>    call_on_irq_stack+0x40/0x74
>    do_interrupt_handler+0x84/0xe4
>    el1_interrupt+0x3c/0x78
> <snip>
>
> Possible unsafe locking scenario:
>         CPU0
>         ----
>    lock(&hwq->cq_lock);
>    <Interrupt>
>      lock(&hwq->cq_lock);
>    *** DEADLOCK ***
> 2 locks held by kworker/u16:4/260:
>
> [name:lockdep&]
>   stack backtrace:
> CPU: 7 PID: 260 Comm: kworker/u16:4 Tainted: G S      W  OE
> 6.1.17-mainline-android14-2-g277223301adb #1
> Workqueue: ufs_eh_wq_0 ufshcd_err_handler
>
>   Call trace:
>    dump_backtrace+0x10c/0x160
>    show_stack+0x20/0x30
>    dump_stack_lvl+0x98/0xd8
>    dump_stack+0x20/0x60
>    print_usage_bug+0x584/0x76c
>    mark_lock_irq+0x488/0x510
>    mark_lock+0x1ec/0x25c
>    __lock_acquire+0x4d8/0xffc
>    lock_acquire+0x17c/0x33c
>    _raw_spin_lock+0x5c/0x7c
>    ufshcd_mcq_poll_cqe_lock+0x30/0xe0
>    ufshcd_poll+0x68/0x1b0
>    ufshcd_transfer_req_compl+0x9c/0xc8
>    ufshcd_err_handler+0x3bc/0xea0
>    process_one_work+0x2f4/0x7e8
>    worker_thread+0x234/0x450
>    kthread+0x110/0x134
>    ret_from_fork+0x10/0x20
>
> ufs_mtk_mcq_intr() could refer to
> https://lore.kernel.org/all/20230328103423.10970-3-powen.kao@xxxxxxxxxxxx/
>
> When ufshcd_err_handler() is executed, CQ event interrupt can enter
> waiting for the same lock. It could happened in upstream code path
> ufshcd_handle_mcq_cq_events() and also in ufs_mtk_mcq_intr(). This
> warning message will be generated when &hwq->cq_lock is used in IRQ
> context with IRQ enabled. Use ufshcd_mcq_poll_cqe_lock() with
> spin_lock_irqsave instead of spin_lock to resolve the deadlock issue.
>
> Signed-off-by: Alice Chao <alice.chao@xxxxxxxxxxxx>
> ---
>   drivers/ufs/core/ufs-mcq.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/ufs/core/ufs-mcq.c b/drivers/ufs/core/ufs-mcq.c
> index 31df052fbc41..202ff71e1b58 100644
> --- a/drivers/ufs/core/ufs-mcq.c
> +++ b/drivers/ufs/core/ufs-mcq.c
> @@ -299,11 +299,11 @@ EXPORT_SYMBOL_GPL(ufshcd_mcq_poll_cqe_nolock);
>   unsigned long ufshcd_mcq_poll_cqe_lock(struct ufs_hba *hba,
>   				       struct ufs_hw_queue *hwq)
>   {
> -	unsigned long completed_reqs;
> +	unsigned long completed_reqs, flags;
>   
> -	spin_lock(&hwq->cq_lock);
> +	spin_lock_irqsave(&hwq->cq_lock, flags);
>   	completed_reqs = ufshcd_mcq_poll_cqe_nolock(hba, hwq);
> -	spin_unlock(&hwq->cq_lock);
> +	spin_unlock_irqrestore(&hwq->cq_lock, flags);
>   
>   	return completed_reqs;
>   }

Reviewed-by: Can Guo <quic_cang@xxxxxxxxxxx>


Thanks for the fix.


Regards,

Can Guo.