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Patch "intel_th: Fix a deadlock in modprobing" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Aug 8, 2016

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This is a note to let you know that I've just added the patch titled

intel_th: Fix a deadlock in modprobing

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
intel_th-fix-a-deadlock-in-modprobing.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From a36aa80f3cb2540fb1dbad6240852de4365a2e82 Mon Sep 17 00:00:00 2001

From: Alexander Shishkin <[email protected]>
Date: Thu, 30 Jun 2016 11:51:44 +0300
Subject: intel_th: Fix a deadlock in modprobing

From: Alexander Shishkin <[email protected]>

commit a36aa80f3cb2540fb1dbad6240852de4365a2e82 upstream.

Driver initialization tries to request a hub (GTH) driver module from its probe callback, resulting in a deadlock.

This patch solves the problem by adding a deferred work for requesting the hub module.

Signed-off-by Alexander Shishkin <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/hwtracing/intel_th/core.c     |   35 +++++++++++++++++++++++++++++++++-
 drivers/hwtracing/intel_th/intel_th.h |    3 ++
 2 files changed, 37 insertions(+), 1 deletion(-)
drivers/hwtracing/intel_th/core.c +34 -1
@@ -419,6 +419,38 @@ static struct intel_th_subdevice {
 	},
 };
 
+#ifdef CONFIG_MODULES
+static void __intel_th_request_hub_module(struct work_struct *work)
+{
+	struct intel_th *th = container_of(work, struct intel_th,
+					   request_module_work);
+
+	request_module("intel_th_%s", th->hub->name);
+}
+
+static int intel_th_request_hub_module(struct intel_th *th)
+{
+	INIT_WORK(&th->request_module_work, __intel_th_request_hub_module);
+	schedule_work(&th->request_module_work);
+
+	return 0;
+}
+
+static void intel_th_request_hub_module_flush(struct intel_th *th)
+{
+	flush_work(&th->request_module_work);
+}
+#else
+static inline int intel_th_request_hub_module(struct intel_th *th)
+{
+	return -EINVAL;
+}
+
+static inline void intel_th_request_hub_module_flush(struct intel_th *th)
+{
+}
+#endif /* CONFIG_MODULES */
+
 static int intel_th_populate(struct intel_th *th, struct resource *devres,
 			     unsigned int ndevres, int irq)
 {

@@ -488,7 +520,7 @@ static int intel_th_populate(struct inte
 		/* need switch driver to be loaded to enumerate the rest */
 		if (subdev->type == INTEL_TH_SWITCH && !req) {
 			th->hub = thdev;
-			err = request_module("intel_th_%s", subdev->name);
+			err = intel_th_request_hub_module(th);
 			if (!err)
 				req++;
 		}

@@ -603,6 +635,7 @@ void intel_th_free(struct intel_th *th)
 {
 	int i;
 
+	intel_th_request_hub_module_flush(th);
 	for (i = 0; i < TH_SUBDEVICE_MAX; i++)
 		if (th->thdev[i] != th->hub)
 			intel_th_device_remove(th->thdev[i]);
drivers/hwtracing/intel_th/intel_th.h +3 -0
@@ -197,6 +197,9 @@ struct intel_th {
 
 	int			id;
 	int			major;
+#ifdef CONFIG_MODULES
+	struct work_struct	request_module_work;
+#endif /* CONFIG_MODULES */
 #ifdef CONFIG_INTEL_TH_DEBUG
 	struct dentry		*dbg;
 #endif

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/intel_th-fix-a-deadlock-in-modprobing.patch queue-4.4/intel_th-pci-add-kaby-lake-pch-h-support.patch