linux-kernel - [PATCH 4.19 251/321] ACPI / APEI: Dont wait to serialise with oops messages when panic()ing

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Message-Id: <20191203223440.195603776@linuxfoundation.org>
Date:   Tue,  3 Dec 2019 23:35:17 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Borislav Petkov <bp@...e.de>,
        James Morse <james.morse@....com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 251/321] ACPI / APEI: Dont wait to serialise with oops messages when panic()ing

From: James Morse <james.morse@....com>

[ Upstream commit 78b0b690f6558ed788dccafa45965325dd11ba89 ]

oops_begin() exists to group printk() messages with the oops message
printed by die(). To reach this caller we know that platform firmware
took this error first, then notified the OS via NMI with a 'panic'
severity.

Don't wait for another CPU to release the die-lock before panic()ing,
our only goal is to print this fatal error and panic().

This code is always called in_nmi(), and since commit 42a0bb3f7138
("printk/nmi: generic solution for safe printk in NMI"), it has been
safe to call printk() from this context. Messages are batched in a
per-cpu buffer and printed via irq-work, or a call back from panic().

Link: https://patchwork.kernel.org/patch/10313555/
Acked-by: Borislav Petkov <bp@...e.de>
Signed-off-by: James Morse <james.morse@....com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/acpi/apei/ghes.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index f008ba7c9cedc..0c46b79e31b1e 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -33,7 +33,6 @@
 #include <linux/interrupt.h>
 #include <linux/timer.h>
 #include <linux/cper.h>
-#include <linux/kdebug.h>
 #include <linux/platform_device.h>
 #include <linux/mutex.h>
 #include <linux/ratelimit.h>
@@ -949,7 +948,6 @@ static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
 
 		sev = ghes_severity(ghes->estatus->error_severity);
 		if (sev >= GHES_SEV_PANIC) {
-			oops_begin();
 			ghes_print_queued_estatus();
 			__ghes_panic(ghes);
 		}
-- 
2.20.1