From: Michael Ellerman <patch-notifications@ellerman•id.au>
To: Breno Leitao <leitao@debian•org>, linuxppc-dev@lists•ozlabs.org
Cc: Breno Leitao <leitao@debian•org>
Subject: Re: powerpc/xmon: Fix invocation inside lock region
Date: Sat, 8 Dec 2018 00:07:01 +1100 (AEDT) [thread overview]
Message-ID: <43BCRT1lMvz9s8J@ozlabs.org> (raw)
In-Reply-To: <1541697162-1926-1-git-send-email-leitao@debian.org>
On Thu, 2018-11-08 at 17:12:42 UTC, Breno Leitao wrote:
> Currently xmon needs to get devtree_lock (through rtas_token()) during its
> invocation (at crash time). If there is a crash while devtree_lock is being
> held, then xmon tries to get the lock but spins forever and never get into
> the interactive debugger, as in the following case:
>
> int *ptr = NULL;
> raw_spin_lock_irqsave(&devtree_lock, flags);
> *ptr = 0xdeadbeef;
>
> This patch avoids calling rtas_token(), thus trying to get the same lock,
> at crash time. This new mechanism proposes getting the token at
> initialization time (xmon_init()) and just consuming it at crash time.
>
> This would allow xmon to be possible invoked independent of devtree_lock
> being held or not.
>
> Signed-off-by: Breno Leitao <leitao@debian•org>
> Reviewed-by: Thiago Jung Bauermann <bauerman@linux•ibm.com>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/8d4a862276a9c30a269d368d324fb5
cheers
prev parent reply other threads:[~2018-12-07 13:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-08 17:12 [PATCH] powerpc/xmon: Fix invocation inside lock region Breno Leitao
2018-11-09 16:22 ` Thiago Jung Bauermann
2018-12-07 13:07 ` Michael Ellerman [this message]
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