drm/amdkfd: Get reference to lead_thread task struct

Increment the kfd_process.lead_thread's reference counter to make
it safe to dereference. This is needed for getting a safe reference
to the process' mm_struct.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index 99c18ee65a7643f674ec3b7f2a27158ec934debf..660d8bcb93e052ea3018afb9fc26fe8dfa7c39bb 100644 (file)
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -24,6 +24,7 @@
 #include <linux/log2.h>
 #include <linux/sched.h>
 #include <linux/sched/mm.h>
+#include <linux/sched/task.h>
 #include <linux/slab.h>
 #include <linux/amd-iommu.h>
 #include <linux/notifier.h>
@@ -191,6 +192,8 @@ static void kfd_process_wq_release(struct work_struct *work)
 
        mutex_destroy(&p->mutex);
 
+       put_task_struct(p->lead_thread);
+
        kfree(p);
 
        kfree(work);
@@ -342,6 +345,7 @@ static struct kfd_process *create_process(const struct task_struct *thread)
                        (uintptr_t)process->mm);
 
        process->lead_thread = thread->group_leader;
+       get_task_struct(process->lead_thread);
 
        INIT_LIST_HEAD(&process->per_device_data);