Re: [PATCH 07/24] drm/amdkfd: check pcs_enrty valid

[Felix Kuehling]

On 2023-11-03 09:11, James Zhu wrote:
Check pcs_enrty valid for pc sampling ioctl.

Signed-off-by: James Zhu <james....@amd.com>
---
  drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c | 30 ++++++++++++++++++--
  1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c 
b/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c
index 4c9fc48e1a6a..36366c8847de 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c
@@ -179,6 +179,21 @@ static int kfd_pc_sample_destroy(struct kfd_process_device 
*pdd, uint32_t trace_
  int kfd_pc_sample(struct kfd_process_device *pdd,
                                        struct kfd_ioctl_pc_sample_args __user 
*args)
  {
+       struct pc_sampling_entry *pcs_entry;
+
+       if (args->op != KFD_IOCTL_PCS_OP_QUERY_CAPABILITIES &&
+               args->op != KFD_IOCTL_PCS_OP_CREATE) {
+
+               mutex_lock(&pdd->dev->pcs_data.mutex);
+               pcs_entry = 
idr_find(&pdd->dev->pcs_data.hosttrap_entry.base.pc_sampling_idr,
+                               args->trace_id);
+               mutex_unlock(&pdd->dev->pcs_data.mutex);

You need to keep holding the lock while the pcs_entry is still used. 
That includes any of the kfd_pc_sample_<op> functions below. Otherwise 
someone could free it concurrently. It would also simplify the ..._<op> 
functions, if they didn't have to worry about the locking themselves.

Regards,
  Felix


+
+               if (!pcs_entry ||
+                       pcs_entry->pdd != pdd)
+                       return -EINVAL;
+       }
+
        switch (args->op) {
        case KFD_IOCTL_PCS_OP_QUERY_CAPABILITIES:
                return kfd_pc_sample_query_cap(pdd, args);
@@ -187,13 +202,22 @@ int kfd_pc_sample(struct kfd_process_device *pdd,
                return kfd_pc_sample_create(pdd, args);
  
  	case KFD_IOCTL_PCS_OP_DESTROY:
-               return kfd_pc_sample_destroy(pdd, args->trace_id);
+               if (pcs_entry->enabled)
+                       return -EBUSY;
+               else
+                       return kfd_pc_sample_destroy(pdd, args->trace_id);
  
  	case KFD_IOCTL_PCS_OP_START:
-               return kfd_pc_sample_start(pdd);
+               if (pcs_entry->enabled)
+                       return -EALREADY;
+               else
+                       return kfd_pc_sample_start(pdd);
  
  	case KFD_IOCTL_PCS_OP_STOP:
-               return kfd_pc_sample_stop(pdd);
+               if (!pcs_entry->enabled)
+                       return -EALREADY;
+               else
+                       return kfd_pc_sample_stop(pdd);
        }
  
  	return -EINVAL;