[PATCH v2 2/2] drm/amdgpu: use spin_lock_irqsave for PASID IDR lock

[Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>]

amdgpu_pasid_free() can be called from hardirq context via the fence
signal path:

  sdma_v6_0_process_trap_irq
   -> amdgpu_fence_process
    -> dma_fence_signal
     -> drm_sched_job_done
      -> dma_fence_signal
       -> amdgpu_pasid_free_cb
        -> amdgpu_pasid_free
         -> spin_lock(&amdgpu_pasid_idr_lock)  <- hardirq context

But the lock was originally taken with plain spin_lock() in process
context (amdgpu_pasid_alloc), creating an inconsistent
{HARDIRQ-ON-W} -> {IN-HARDIRQ-W} lock state that can deadlock if an
interrupt arrives while the lock is held on the same CPU.

Use spin_lock_irqsave/spin_unlock_irqrestore for all call sites of
amdgpu_pasid_idr_lock to prevent the deadlock.

This patch applies on top of "drm/amdgpu: fix sleeping allocation
under spinlock in PASID IDR".

Fixes: 8f1de51f49be ("drm/amdgpu: prevent immediate PASID reuse case")
Cc: stable@vger.kernel.org
Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
index 515775eab2ef..762ceb3c708a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
@@ -62,16 +62,17 @@ struct amdgpu_pasid_cb {
  */
 int amdgpu_pasid_alloc(unsigned int bits)
 {
+	unsigned long flags;
 	int pasid;
 
 	if (bits == 0)
 		return -EINVAL;
 
 	idr_preload(GFP_KERNEL);
-	spin_lock(&amdgpu_pasid_idr_lock);
+	spin_lock_irqsave(&amdgpu_pasid_idr_lock, flags);
 	pasid = idr_alloc_cyclic(&amdgpu_pasid_idr, NULL, 1,
 				 1U << bits, GFP_NOWAIT);
-	spin_unlock(&amdgpu_pasid_idr_lock);
+	spin_unlock_irqrestore(&amdgpu_pasid_idr_lock, flags);
 	idr_preload_end();
 
 	if (pasid >= 0)
@@ -86,11 +87,12 @@ int amdgpu_pasid_alloc(unsigned int bits)
  */
 void amdgpu_pasid_free(u32 pasid)
 {
+	unsigned long flags;
 	trace_amdgpu_pasid_freed(pasid);
 
-	spin_lock(&amdgpu_pasid_idr_lock);
+	spin_lock_irqsave(&amdgpu_pasid_idr_lock, flags);
 	idr_remove(&amdgpu_pasid_idr, pasid);
-	spin_unlock(&amdgpu_pasid_idr_lock);
+	spin_unlock_irqrestore(&amdgpu_pasid_idr_lock, flags);
 }
 
 static void amdgpu_pasid_free_cb(struct dma_fence *fence,
@@ -633,7 +635,9 @@ void amdgpu_vmid_mgr_fini(struct amdgpu_device *adev)
  */
 void amdgpu_pasid_mgr_cleanup(void)
 {
-	spin_lock(&amdgpu_pasid_idr_lock);
+	unsigned long flags;
+
+	spin_lock_irqsave(&amdgpu_pasid_idr_lock, flags);
 	idr_destroy(&amdgpu_pasid_idr);
-	spin_unlock(&amdgpu_pasid_idr_lock);
+	spin_unlock_irqrestore(&amdgpu_pasid_idr_lock, flags);
 }
-- 
2.53.0