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PM: sleep: Avoid using pr_cont() in the tasks freezing code

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Using pr_cont() in the tasks freezing code related to system-wide
suspend and hibernation is problematic, because the continuation
messages printed there are susceptible to interspersing with other
unrelated messages which results in output that is hard to
understand.

Address this issue by modifying try_to_freeze_tasks() to print
messages that don't require continuations and adjusting its
callers accordingly.

Reported-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
This commit is contained in:
Rafael J. Wysocki 2022-12-01 19:33:09 +01:00
parent 3363e0adb3
commit a449dfbfc0
1 changed files with 8 additions and 13 deletions
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21
kernel/power/process.c
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@ -27,6 +27,8 @@ unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC;
static int try_to_freeze_tasks(bool user_only) static int try_to_freeze_tasks(bool user_only)
{ {
const char *what = user_only ? "user space processes" :
"remaining freezable tasks";
struct task_struct *g, *p; struct task_struct *g, *p;
unsigned long end_time; unsigned long end_time;
unsigned int todo; unsigned int todo;
@ -36,6 +38,8 @@ static int try_to_freeze_tasks(bool user_only)
bool wakeup = false; bool wakeup = false;
int sleep_usecs = USEC_PER_MSEC; int sleep_usecs = USEC_PER_MSEC;
pr_info("Freezing %s\n", what);
start = ktime_get_boottime(); start = ktime_get_boottime();
end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs); end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
@ -82,7 +86,6 @@ static int try_to_freeze_tasks(bool user_only)
elapsed_msecs = ktime_to_ms(elapsed); elapsed_msecs = ktime_to_ms(elapsed);
if (todo) { if (todo) {
pr_cont("\n");
pr_err("Freezing of tasks %s after %d.%03d seconds " pr_err("Freezing of tasks %s after %d.%03d seconds "
"(%d tasks refusing to freeze, wq_busy=%d):\n", "(%d tasks refusing to freeze, wq_busy=%d):\n",
wakeup ? "aborted" : "failed", wakeup ? "aborted" : "failed",
@ -101,8 +104,8 @@ static int try_to_freeze_tasks(bool user_only)
read_unlock(&tasklist_lock); read_unlock(&tasklist_lock);
} }
} else { } else {
pr_cont("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000, pr_info("Freezing %s completed (elapsed %d.%03d seconds)\n",
elapsed_msecs % 1000); what, elapsed_msecs / 1000, elapsed_msecs % 1000);
} }
return todo ? -EBUSY : 0; return todo ? -EBUSY : 0;
@ -130,14 +133,11 @@ int freeze_processes(void)
static_branch_inc(&freezer_active); static_branch_inc(&freezer_active);
pm_wakeup_clear(0); pm_wakeup_clear(0);
pr_info("Freezing user space processes ... ");
pm_freezing = true; pm_freezing = true;
error = try_to_freeze_tasks(true); error = try_to_freeze_tasks(true);
if (!error) { if (!error)
__usermodehelper_set_disable_depth(UMH_DISABLED); __usermodehelper_set_disable_depth(UMH_DISABLED);
pr_cont("done.");
}
pr_cont("\n");
BUG_ON(in_atomic()); BUG_ON(in_atomic());
/* /*
@ -166,14 +166,9 @@ int freeze_kernel_threads(void)
{ {
int error; int error;
pr_info("Freezing remaining freezable tasks ... ");
pm_nosig_freezing = true; pm_nosig_freezing = true;
error = try_to_freeze_tasks(false); error = try_to_freeze_tasks(false);
if (!error)
pr_cont("done.");
pr_cont("\n");
BUG_ON(in_atomic()); BUG_ON(in_atomic());
if (error) if (error)