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From: Hanjun Guo <guohanjun@huawei.com>
To: Jamie Iles <jamie@nuviainc.com>, <linux-acpi@vger.kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: [PATCHv2] ACPI: debug: don't allow debugging when ACPI is disabled
Date: Wed, 14 Oct 2020 08:43:02 +0800	[thread overview]
Message-ID: <b332a42a-cb5d-ad2a-99f5-77df748c343a@huawei.com> (raw)
In-Reply-To: <20201012130446.57325-1-jamie@nuviainc.com>

On 2020/10/12 21:04, Jamie Iles wrote:
> If ACPI is disabled then loading the acpi_dbg module will result in the
> following splat when lock debugging is enabled.
> 
>    DEBUG_LOCKS_WARN_ON(lock->magic != lock)
>    WARNING: CPU: 0 PID: 1 at kernel/locking/mutex.c:938 __mutex_lock+0xa10/0x1290
>    Kernel panic - not syncing: panic_on_warn set ...
>    CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc8+ #103
>    Hardware name: linux,dummy-virt (DT)
>    Call trace:
>     dump_backtrace+0x0/0x4d8
>     show_stack+0x34/0x48
>     dump_stack+0x174/0x1f8
>     panic+0x360/0x7a0
>     __warn+0x244/0x2ec
>     report_bug+0x240/0x398
>     bug_handler+0x50/0xc0
>     call_break_hook+0x160/0x1d8
>     brk_handler+0x30/0xc0
>     do_debug_exception+0x184/0x340
>     el1_dbg+0x48/0xb0
>     el1_sync_handler+0x170/0x1c8
>     el1_sync+0x80/0x100
>     __mutex_lock+0xa10/0x1290
>     mutex_lock_nested+0x6c/0xc0
>     acpi_register_debugger+0x40/0x88
>     acpi_aml_init+0xc4/0x114
>     do_one_initcall+0x24c/0xb10
>     kernel_init_freeable+0x690/0x728
>     kernel_init+0x20/0x1e8
>     ret_from_fork+0x10/0x18
> 
> This is because acpi_debugger.lock has not been initialized as
> acpi_debugger_init() is not called when ACPI is disabled.  Fail module
> loading to avoid this and any subsequent problems that might arise by
> trying to debug AML when ACPI is disabled.
> 
> Fixes: 8cfb0cdf07e2 ("ACPI / debugger: Add IO interface to access debugger functionalities")
> Reviewed-by: Hanjun Guo <guohanjun@huawei.com>

My review still valid, thanks!

Hanjun

  reply	other threads:[~2020-10-14  0:43 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-09 15:21 [PATCH] ACPI: debug: don't allow debugging when ACPI is disabled Jamie Iles
2020-10-10  3:27 ` Hanjun Guo
2020-10-12 13:04 ` [PATCHv2] " Jamie Iles
2020-10-14  0:43   ` Hanjun Guo [this message]
2020-10-16 16:00   ` Rafael J. Wysocki

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