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Date:   Mon, 27 Apr 2020 14:40:39 +0100
From:   Daniel Thompson <daniel.thompson@linaro.org>
To:     Douglas Anderson <dianders@chromium.org>
Cc:     jason.wessel@windriver.com, gregkh@linuxfoundation.org,
        kgdb-bugreport@lists.sourceforge.net, mingo@redhat.com,
        hpa@zytor.com, bp@alien8.de, linux-serial@vger.kernel.org,
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        catalin.marinas@arm.com, corbet@lwn.net, will@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/9] kgdb: Disable WARN_CONSOLE_UNLOCKED for all kgdb
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References: <20200421211447.193860-1-dianders@chromium.org>
 <20200421141234.v2.1.Ied2b058357152ebcc8bf68edd6f20a11d98d7d4e@changeid>
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On Tue, Apr 21, 2020 at 02:14:39PM -0700, Douglas Anderson wrote:
> In commit 81eaadcae81b ("kgdboc: disable the console lock when in
> kgdb") we avoided the WARN_CONSOLE_UNLOCKED() yell when we were in
> kgdboc.  That still works fine, but it turns out that we get a similar
> yell when using other I/O drivers.  One example is the "I/O driver"
> for the kgdb test suite (kgdbts).  When I enabled that I again got the
> same yells.
> 
> Even though "kgdbts" doesn't actually interact with the user over the
> console, using it still causes kgdb to print to the consoles.  That
> trips the same warning:
>   con_is_visible+0x60/0x68
>   con_scroll+0x110/0x1b8
>   lf+0x4c/0xc8
>   vt_console_print+0x1b8/0x348
>   vkdb_printf+0x320/0x89c
>   kdb_printf+0x68/0x90
>   kdb_main_loop+0x190/0x860
>   kdb_stub+0x2cc/0x3ec
>   kgdb_cpu_enter+0x268/0x744
>   kgdb_handle_exception+0x1a4/0x200
>   kgdb_compiled_brk_fn+0x34/0x44
>   brk_handler+0x7c/0xb8
>   do_debug_exception+0x1b4/0x228
> 
> Let's increment/decrement the "ignore_console_lock_warning" variable
> all the time when we enter the debugger.
> 
> This will allow us to later revert commit 81eaadcae81b ("kgdboc:
> disable the console lock when in kgdb").
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>