From: "Luck, Tony" <tony.luck@intel.com>
To: Yang Li <yang.lee@linux.alibaba.com>
Cc: "bp@alien8.de" <bp@alien8.de>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"x86@kernel.org" <x86@kernel.org>,
"hpa@zytor.com" <hpa@zytor.com>,
"linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] x86/mce/dev-mcelog: Fix potential memory access error
Date: Mon, 29 Mar 2021 16:12:16 +0000 [thread overview]
Message-ID: <745eaeb668bc43deb8eb7db7a3342691@intel.com> (raw)
In-Reply-To: <1617011360-102531-1-git-send-email-yang.lee@linux.alibaba.com>
- set_bit(MCE_OVERFLOW, (unsigned long *)&mcelog->flags);
+ mcelog->flags |= BIT(MCE_OVERFLOW);
set_bit() is an atomic operation because it might race with the code to
get and clear this bit:
do {
flags = mcelog->flags;
} while (cmpxchg(&mcelog->flags, flags, 0) != flags);
Originally this was needed because mcelog could be called from #MC
context.
That's all changed now and the machine check notifier chain routines are
called in a kernel thread. So some other locking (mutex?) could be used
to protect access to mcelog->flags.
-Tony
prev parent reply other threads:[~2021-03-29 16:13 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-29 9:49 [PATCH] x86/mce/dev-mcelog: Fix potential memory access error Yang Li
2021-03-29 16:12 ` Luck, Tony [this message]
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