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

[Stanley Chu]

Hi Alice,

Alice Chao <alice.chao@xxxxxxxxxxxx> 於 2023年4月21日 週五 下午3:58寫道：
>
> [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>
> ---

After adding a Fixes: tag, feel free to add,

Reviewed-by: Stanley Chu <stanley.chu@xxxxxxxxxxxx>