PM: base: power: don't try to use non-existing RTC for storing data

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>

diff --git a/drivers/base/power/trace.c b/drivers/base/power/trace.c
index a97f33d..9466503 100644 (file)
--- 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;
+
        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;