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Commit a36aa80f authored by Alexander Shishkin's avatar Alexander Shishkin
Browse files

intel_th: Fix a deadlock in modprobing 



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: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: <stable@vger.kernel.org> # 4.4.x-
parent af8c34ce

drivers/hwtracing/intel_th/core.c

+34 −1
Original line number Diff line number Diff line
@@ -465,6 +465,38 @@ 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)

{
@@ -535,7 +567,7 @@ 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++;

		}
@@ -652,6 +684,7 @@ 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
Original line number Diff line number Diff line
@@ -205,6 +205,9 @@ 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