From: Borislav Petkov <bp@alien8.de>
To: linux-edac <linux-edac@vger.kernel.org>
Cc: Jiri Kosina <jkosina@suse.cz>, Borislav Petkov <bp@suse.de>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <lenb@kernel.org>, Tony Luck <tony.luck@intel.com>,
Tomasz Nowicki <tomasz.nowicki@linaro.org>,
"Chen, Gong" <gong.chen@linux.intel.com>,
Wolfram Sang <wsa@the-dreams.de>, Lv Zheng <lv.zheng@intel.com>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [RFC PATCH 5/5] GHES: Make NMI handler have a single reader
Date: Fri, 27 Mar 2015 10:22:58 +0100 [thread overview]
Message-ID: <1427448178-20689-6-git-send-email-bp@alien8.de> (raw)
In-Reply-To: <1427448178-20689-1-git-send-email-bp@alien8.de>
From: Jiri Kosina <jkosina@suse.cz>
Since GHES sources are global, we theoretically need only a single CPU
reading them per NMI instead of a thundering herd of CPUs waiting on a
spinlock in NMI context for no reason at all.
Do that.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Borislav Petkov <bp@suse.de>
---
drivers/acpi/apei/ghes.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 94a44bad5576..2bfd53cbfe80 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -729,10 +729,10 @@ static struct llist_head ghes_estatus_llist;
static struct irq_work ghes_proc_irq_work;
/*
- * NMI may be triggered on any CPU, so ghes_nmi_lock is used for
- * mutual exclusion.
+ * NMI may be triggered on any CPU, so ghes_in_nmi is used for
+ * having only one concurrent reader.
*/
-static DEFINE_RAW_SPINLOCK(ghes_nmi_lock);
+static atomic_t ghes_in_nmi = ATOMIC_INIT(0);
static LIST_HEAD(ghes_nmi);
@@ -840,7 +840,9 @@ static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
struct ghes *ghes;
int sev, ret = NMI_DONE;
- raw_spin_lock(&ghes_nmi_lock);
+ if (!atomic_add_unless(&ghes_in_nmi, 1, 1))
+ return ret;
+
list_for_each_entry_rcu(ghes, &ghes_nmi, list) {
if (ghes_read_estatus(ghes, 1)) {
ghes_clear_estatus(ghes);
@@ -863,7 +865,7 @@ static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
irq_work_queue(&ghes_proc_irq_work);
#endif
- raw_spin_unlock(&ghes_nmi_lock);
+ atomic_dec(&ghes_in_nmi);
return ret;
}
--
2.3.3
next prev parent reply other threads:[~2015-03-27 9:25 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-27 9:22 [RFC PATCH 0/5] GHES NMI handler cleanup Borislav Petkov
2015-03-27 9:22 ` [RFC PATCH 1/5] GHES: Carve out error queueing in a separate function Borislav Petkov
2015-03-27 9:22 ` [RFC PATCH 2/5] GHES: Carve out the panic functionality Borislav Petkov
2015-03-27 9:22 ` [RFC PATCH 3/5] GHES: Panic right after detection Borislav Petkov
2015-03-27 9:22 ` [RFC PATCH 4/5] GHES: Elliminate double-loop in the NMI handler Borislav Petkov
2015-03-27 9:22 ` Borislav Petkov [this message]
2015-04-01 7:45 ` [RFC PATCH 5/5] GHES: Make NMI handler have a single reader Jiri Kosina
2015-04-01 13:49 ` Borislav Petkov
2015-04-23 8:39 ` Jiri Kosina
2015-04-23 8:59 ` Borislav Petkov
2015-04-23 18:00 ` Luck, Tony
2015-04-27 20:23 ` Borislav Petkov
2015-04-28 14:30 ` Don Zickus
2015-04-28 14:42 ` Don Zickus
2015-04-28 14:55 ` Borislav Petkov
2015-04-28 15:35 ` Don Zickus
2015-04-28 16:22 ` Borislav Petkov
2015-04-28 18:44 ` Don Zickus
2015-05-04 15:40 ` Borislav Petkov
2015-04-27 3:16 ` Zheng, Lv
2015-04-27 8:46 ` Borislav Petkov
2015-04-28 0:44 ` Zheng, Lv
2015-04-28 2:24 ` Zheng, Lv
2015-04-28 7:38 ` Borislav Petkov
2015-04-28 13:38 ` Zheng, Lv
2015-04-28 13:59 ` Borislav Petkov
2015-04-29 0:24 ` Zheng, Lv
2015-04-29 0:49 ` Zheng, Lv
2015-04-29 8:13 ` Borislav Petkov
2015-04-30 8:05 ` Zheng, Lv
2015-04-30 8:48 ` Borislav Petkov
2015-05-02 0:34 ` Zheng, Lv
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