stable/linux-4.14.y bisection: boot on odroid-x2

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stable/linux-4.14.y bisection: boot on odroid-x2

Summary:
  Start:      f56f3d0e65ad Linux 4.14.155
  Details:    https://kernelci.org/boot/id/5dd5a12159b5143a10cf54c3
  Plain log:  https://storage.kernelci.org//stable/linux-4.14.y/v4.14.155/arm/exynos_defconfig/gcc-8/lab-collabora/boot-exynos4412-odroidx2.txt
  HTML log:   https://storage.kernelci.org//stable/linux-4.14.y/v4.14.155/arm/exynos_defconfig/gcc-8/lab-collabora/boot-exynos4412-odroidx2.html
  Result:     714ab224a8db OPP: Protect dev_list with opp_table lock

Checks:
  revert:     PASS
  verify:     PASS

Parameters:
  Tree:       stable
  URL:        https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
  Branch:     linux-4.14.y
  Target:     odroid-x2
  CPU arch:   arm
  Lab:        lab-collabora
  Compiler:   gcc-8
  Config:     exynos_defconfig
  Test suite: boot

Breaking commit found:

-------------------------------------------------------------------------------
commit 714ab224a8db6e8255c61a42613de9349ceb0bba
Author: Viresh Kumar <viresh.kumar@linaro.org>
Date:   Fri Aug 3 07:05:21 2018 +0530

    OPP: Protect dev_list with opp_table lock
    
    [ Upstream commit 3d2556992a878a2210d3be498416aee39e0c32aa ]
    
    The dev_list needs to be protected with a lock, else we may have
    simultaneous access (addition/removal) to it and that would be racy.
    Extend scope of the opp_table lock to protect dev_list as well.
    
    Tested-by: Niklas Cassel <niklas.cassel@linaro.org>
    Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
index d5e7e8cc4f22..8100c8769149 100644
--- a/drivers/base/power/opp/core.c
+++ b/drivers/base/power/opp/core.c
@@ -49,9 +49,14 @@ static struct opp_device *_find_opp_dev(const struct device *dev,
 static struct opp_table *_find_opp_table_unlocked(struct device *dev)
 {
 	struct opp_table *opp_table;
+	bool found;
 
 	list_for_each_entry(opp_table, &opp_tables, node) {
-		if (_find_opp_dev(dev, opp_table)) {
+		mutex_lock(&opp_table->lock);
+		found = !!_find_opp_dev(dev, opp_table);
+		mutex_unlock(&opp_table->lock);
+
+		if (found) {
 			_get_opp_table_kref(opp_table);
 
 			return opp_table;
@@ -711,6 +716,8 @@ struct opp_device *_add_opp_dev(const struct device *dev,
 
 	/* Initialize opp-dev */
 	opp_dev->dev = dev;
+
+	mutex_lock(&opp_table->lock);
 	list_add(&opp_dev->node, &opp_table->dev_list);
 
 	/* Create debugfs entries for the opp_table */
@@ -718,6 +725,7 @@ struct opp_device *_add_opp_dev(const struct device *dev,
 	if (ret)
 		dev_err(dev, "%s: Failed to register opp debugfs (%d)\n",
 			__func__, ret);
+	mutex_unlock(&opp_table->lock);
 
 	return opp_dev;
 }
@@ -736,6 +744,7 @@ static struct opp_table *_allocate_opp_table(struct device *dev)
 	if (!opp_table)
 		return NULL;
 
+	mutex_init(&opp_table->lock);
 	INIT_LIST_HEAD(&opp_table->dev_list);
 
 	opp_dev = _add_opp_dev(dev, opp_table);
@@ -757,7 +766,6 @@ static struct opp_table *_allocate_opp_table(struct device *dev)
 
 	BLOCKING_INIT_NOTIFIER_HEAD(&opp_table->head);
 	INIT_LIST_HEAD(&opp_table->opp_list);
-	mutex_init(&opp_table->lock);
 	kref_init(&opp_table->kref);
 
 	/* Secure the device table modification */
@@ -799,6 +807,10 @@ static void _opp_table_kref_release(struct kref *kref)
 	if (!IS_ERR(opp_table->clk))
 		clk_put(opp_table->clk);
 
+	/*
+	 * No need to take opp_table->lock here as we are guaranteed that no
+	 * references to the OPP table are taken at this point.
+	 */
 	opp_dev = list_first_entry(&opp_table->dev_list, struct opp_device,
 				   node);
 
@@ -1702,6 +1714,9 @@ void _dev_pm_opp_remove_table(struct opp_table *opp_table, struct device *dev,
 {
 	struct dev_pm_opp *opp, *tmp;
 
+	/* Protect dev_list */
+	mutex_lock(&opp_table->lock);
+
 	/* Find if opp_table manages a single device */
 	if (list_is_singular(&opp_table->dev_list)) {
 		/* Free static OPPs */
@@ -1712,6 +1727,8 @@ void _dev_pm_opp_remove_table(struct opp_table *opp_table, struct device *dev,
 	} else {
 		_remove_opp_dev(_find_opp_dev(dev, opp_table), opp_table);
 	}
+
+	mutex_unlock(&opp_table->lock);
 }
 
 void _dev_pm_opp_find_and_remove_table(struct device *dev, bool remove_all)
diff --git a/drivers/base/power/opp/cpu.c b/drivers/base/power/opp/cpu.c
index 2d87bc1adf38..66e406bd4d62 100644
--- a/drivers/base/power/opp/cpu.c
+++ b/drivers/base/power/opp/cpu.c
@@ -222,8 +222,10 @@ int dev_pm_opp_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
 	cpumask_clear(cpumask);
 
 	if (opp_table->shared_opp == OPP_TABLE_ACCESS_SHARED) {
+		mutex_lock(&opp_table->lock);
 		list_for_each_entry(opp_dev, &opp_table->dev_list, node)
 			cpumask_set_cpu(opp_dev->dev->id, cpumask);
+		mutex_unlock(&opp_table->lock);
 	} else {
 		cpumask_set_cpu(cpu_dev->id, cpumask);
 	}
diff --git a/drivers/base/power/opp/opp.h b/drivers/base/power/opp/opp.h
index 166eef990599..0a206c6b9086 100644
--- a/drivers/base/power/opp/opp.h
+++ b/drivers/base/power/opp/opp.h
@@ -124,7 +124,7 @@ enum opp_table_access {
  * @dev_list:	list of devices that share these OPPs
  * @opp_list:	table of opps
  * @kref:	for reference count of the table.
- * @lock:	mutex protecting the opp_list.
+ * @lock:	mutex protecting the opp_list and dev_list.
  * @np:		struct device_node pointer for opp's DT node.
  * @clock_latency_ns_max: Max clock latency in nanoseconds.
  * @shared_opp: OPP is shared between multiple devices.
-------------------------------------------------------------------------------


Git bisection log:

-------------------------------------------------------------------------------
git bisect start
# good: [775d01b65b5daa002a9ba60f2d2bb3b1a6ce12fb] Linux 4.14.154
git bisect good 775d01b65b5daa002a9ba60f2d2bb3b1a6ce12fb
# bad: [f56f3d0e65adb447b8b583c8ed4fbbe544c9bfde] Linux 4.14.155
git bisect bad f56f3d0e65adb447b8b583c8ed4fbbe544c9bfde
# good: [46af2022de198ebbf47141b7b33522e28733045d] arm64: dts: meson: Fix erroneous SPI bus warnings
git bisect good 46af2022de198ebbf47141b7b33522e28733045d
# bad: [0b9c70939b60221f2210ef55a325fec6dea8cde1] media: au0828: Fix incorrect error messages
git bisect bad 0b9c70939b60221f2210ef55a325fec6dea8cde1
# bad: [70c3daaa03e965d3f2bd10696be130b376f73bca] net: broadcom: fix return type of ndo_start_xmit function
git bisect bad 70c3daaa03e965d3f2bd10696be130b376f73bca
# good: [45503ce9086cabc9b3faaaed4563b2da8af1ffe2] samples/bpf: fix a compilation failure
git bisect good 45503ce9086cabc9b3faaaed4563b2da8af1ffe2
# good: [9bee4f9f4460db86c47fe01f9671af6a8951efda] powerpc: Fix duplicate const clang warning in user access code
git bisect good 9bee4f9f4460db86c47fe01f9671af6a8951efda
# bad: [b1fdcfbdb93cc899d19091a2385edb40a07420e3] power: supply: twl4030_charger: fix charging current out-of-bounds
git bisect bad b1fdcfbdb93cc899d19091a2385edb40a07420e3
# bad: [714ab224a8db6e8255c61a42613de9349ceb0bba] OPP: Protect dev_list with opp_table lock
git bisect bad 714ab224a8db6e8255c61a42613de9349ceb0bba
# good: [7dbc3efb7430abdddf0be186bd0ad2611d767d23] RDMA/i40iw: Fix incorrect iterator type
git bisect good 7dbc3efb7430abdddf0be186bd0ad2611d767d23
# first bad commit: [714ab224a8db6e8255c61a42613de9349ceb0bba] OPP: Protect dev_list with opp_table lock
-------------------------------------------------------------------------------