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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: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: <stable@vger.kernel.org> # 4.4.x-
This commit is contained in:
Alexander Shishkin 2016-06-30 11:51:44 +03:00
parent af8c34ce6a
commit a36aa80f3c
2 changed files with 37 additions and 1 deletions
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35
drivers/hwtracing/intel_th/core.c
View File

@ -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]);

3
drivers/hwtracing/intel_th/intel_th.h
View File

@ -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