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 <stable@xxxxxxxxxxxxxxx> know about it.
>From a36aa80f3cb2540fb1dbad6240852de4365a2e82 Mon Sep 17 00:00:00 2001
From: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Date: Thu, 30 Jun 2016 11:51:44 +0300
Subject: intel_th: Fix a deadlock in modprobing
From: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
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 <alexander.shishkin@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/hwtracing/intel_th/core.c | 35 +++++++++++++++++++++++++++++++++-
drivers/hwtracing/intel_th/intel_th.h | 3 ++
2 files changed, 37 insertions(+), 1 deletion(-)
--- a/drivers/hwtracing/intel_th/core.c
+++ b/drivers/hwtracing/intel_th/core.c
@@ -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]);
--- a/drivers/hwtracing/intel_th/intel_th.h
+++ b/drivers/hwtracing/intel_th/intel_th.h
@@ -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 alexander.shishkin@xxxxxxxxxxxxxxx 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
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