From 33f9cff6ec2fbfcf0b40d4328d292c745185fdf4 Mon Sep 17 00:00:00 2001
From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Date: Thu, 30 Jun 2016 11:51:44 +0300
Subject: [PATCH] intel_th: Fix a deadlock in modprobing
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@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/hwtracing/intel_th/core.c | 35 ++++++++++++++++++++++++++-
drivers/hwtracing/intel_th/intel_th.h | 3 +++
2 files changed, 37 insertions(+), 1 deletion(-)
diff --git a/drivers/hwtracing/intel_th/core.c b/drivers/hwtracing/intel_th/core.c
index 165d3001c3015..c6ec5c62b7a9e 100644
--- 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 intel_th *th, struct resource *devres,
/* 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]);
diff --git a/drivers/hwtracing/intel_th/intel_th.h b/drivers/hwtracing/intel_th/intel_th.h
index 57fd72b20fae3..d03a6cd1c65d5 100644
--- 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