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Subject[PATCH 5.4 196/260] PM: base: power: dont try to use non-existing RTC for storing data
Date
From: Juergen Gross <jgross@suse.com>

commit 0560204b360a332c321124dbc5cdfd3364533a74 upstream.

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

Cc: <stable@vger.kernel.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20210903084937.19392-2-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/base/power/trace.c | 10 ++++++++++
1 file changed, 10 insertions(+)

--- 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 *trace
const char *file = *(const char **)(tracedata + 2);
unsigned int user_hash_value, file_hash_value;

+ if (!x86_platform.legacy.rtc)
+ return;
+
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 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 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;

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