linux-kernel - [PATCH 1/2] PM: base: power: don't try to use non-existing RTC for storing data

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Message-Id: <20210903084937.19392-2-jgross@suse.com>
Date:   Fri,  3 Sep 2021 10:49:36 +0200
From:   Juergen Gross <jgross@...e.com>
To:     xen-devel@...ts.xenproject.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Juergen Gross <jgross@...e.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>, stable@...r.kernel.org
Subject: [PATCH 1/2] PM: base: power: don't try to use non-existing RTC for storing data

In there is no legacy RTC device, don't try to use it for storing trace
data across suspend/resume.

Cc: <stable@...r.kernel.org>
Signed-off-by: Juergen Gross <jgross@...e.com>
---
 drivers/base/power/trace.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/base/power/trace.c b/drivers/base/power/trace.c
index a97f33d0c59f..b7c80849455c 100644
--- a/drivers/base/power/trace.c
+++ b/drivers/base/power/trace.c
@@ -13,6 +13,7 @@
 #include <linux/export.h>
 #include <linux/rtc.h>
 #include <linux/suspend.h>
+#include <linux/init.h>
 
 #include <linux/mc146818rtc.h>
 
@@ -165,6 +166,9 @@ void generate_pm_trace(const void *tracedata, unsigned int user)
 	const char *file = *(const char **)(tracedata + 2);
 	unsigned int user_hash_value, file_hash_value;
 
+	if (!x86_platform.legacy.rtc)
+		return 0;
+
 	user_hash_value = user % USERHASH;
 	file_hash_value = hash_string(lineno, file, FILEHASH);
 	set_magic_time(user_hash_value, file_hash_value, dev_hash_value);
@@ -267,6 +271,9 @@ static struct notifier_block pm_trace_nb = {
 
 static int __init early_resume_init(void)
 {
+	if (!x86_platform.legacy.rtc)
+		return 0;
+
 	hash_value_early_read = read_magic_time();
 	register_pm_notifier(&pm_trace_nb);
 	return 0;
@@ -277,6 +284,9 @@ static int __init late_resume_init(void)
 	unsigned int val = hash_value_early_read;
 	unsigned int user, file, dev;
 
+	if (!x86_platform.legacy.rtc)
+		return 0;
+
 	user = val % USERHASH;
 	val = val / USERHASH;
 	file = val % FILEHASH;
-- 
2.26.2