From: John David Anglin <dave.anglin@bell.net>
To: Helge Deller <deller@gmx.de>, linux-parisc@vger.kernel.org
Subject: Re: [PATCH] parisc: Fix lightweight spinlock checks to not break futexes
Date: Thu, 10 Aug 2023 10:57:54 -0400 [thread overview]
Message-ID: <a28de2c8-edce-0f2b-0d2a-075fcbf05e3f@bell.net> (raw)
In-Reply-To: <ZNM8Rz5f5/d/ZAI8@p100>
On 2023-08-09 3:12 a.m., Helge Deller wrote:
> The lightweight spinlock checks verify that a spinlock has either value
> 0 (spinlock locked) and that not any other bits than in
> __ARCH_SPIN_LOCK_UNLOCKED_VAL is set.
>
> This breaks the current LWS code, which writes the address of the lock
> into the lock word to unlock it, which was an optimization to save one
> assembler instruction.
>
> Fix it by making spinlock_types.h accessible for asm code, change the
> LWS spinlock-unlocking code to write __ARCH_SPIN_LOCK_UNLOCKED_VAL into
> the lock word, and add some missing lightweight spinlock checks to the
> LWS path. Finally, make the spinlock checks dependend on DEBUG_KERNEL.
>
> Noticed-by: John David Anglin<dave.anglin@bell.net>
> Signed-off-by: Helge Deller<deller@gmx.de>
> Cc:stable@vger.kernel.org # v6.4+
> Fixes: 15e64ef6520e ("parisc: Add lightweight spinlock checks")
Fixes system crash in glibc testsuite.
Tested-by: John David Anglin <dave.anglin@bell.net>
--
John David Anglin dave.anglin@bell.net
prev parent reply other threads:[~2023-08-10 14:57 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-09 7:12 [PATCH] parisc: Fix lightweight spinlock checks to not break futexes Helge Deller
2023-08-10 14:57 ` John David Anglin [this message]
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