linux-kernel - [PATCH] power: avoid calling cancel_delayed_work

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Message-ID: <20160905123813.GB20784@mtj.duckdns.org>
Date:   Mon, 5 Sep 2016 08:38:13 -0400
From:   Tejun Heo <tj@...nel.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     linux-pm@...r.kernel.org, Wang Wilbur <wilburwang@...micro.com>,
        Wu Gang <gangwu@...micro.com>, linux-kernel@...r.kernel.org,
        qiaozhou <qiaozhou@...micro.com>
Subject: [PATCH] power: avoid calling cancel_delayed_work_sync() during early
 boot

of_clk_init() ends up calling into pm_qos_update_request() very early
during boot where irq is expected to stay disabled.
pm_qos_update_request() uses cancel_delayed_work_sync() which
correctly assumes that irq is enabled on invocation and
unconditionally disables and re-enables it.

Gate cancel_delayed_work_sync() invocation with kevented_up() to avoid
enabling irq unexpectedly during early boot.

Signed-off-by: Tejun Heo <tj@...nel.org>
Reported-and-tested-by: Qiao Zhou <qiaozhou@...micro.com>
Link: http://lkml.kernel.org/r/d2501c4c-8e7b-bea3-1b01-000b36b5dfe9@asrmicro.com
---

Rafael, can you please route this patch?

Thanks.

 kernel/power/qos.c |   11 ++++++++++-
  1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/power/qos.c b/kernel/power/qos.c
index 97b0df7..168ff44 100644
--- a/kernel/power/qos.c
+++ b/kernel/power/qos.c
@@ -482,7 +482,16 @@ void pm_qos_update_request(struct pm_qos_request *req,
 		return;
 	}
 
-	cancel_delayed_work_sync(&req->work);
+	/*
+	 * This function may be called very early during boot, for example,
+	 * from of_clk_init(), where irq needs to stay disabled.
+	 * cancel_delayed_work_sync() assumes that irq is enabled on
+	 * invocation and re-enables it on return.  Avoid calling it until
+	 * workqueue is initialized.
+	 */
+	if (keventd_up())
+		cancel_delayed_work_sync(&req->work);
+
 	__pm_qos_update_request(req, new_value);
 }
 EXPORT_SYMBOL_GPL(pm_qos_update_request);