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-rw-r--r--debian/patches-rt/0290-dma-buf-Use-seqlock_t-instread-disabling-preemption.patch296
1 files changed, 296 insertions, 0 deletions
diff --git a/debian/patches-rt/0290-dma-buf-Use-seqlock_t-instread-disabling-preemption.patch b/debian/patches-rt/0290-dma-buf-Use-seqlock_t-instread-disabling-preemption.patch
new file mode 100644
index 000000000..5376a0901
--- /dev/null
+++ b/debian/patches-rt/0290-dma-buf-Use-seqlock_t-instread-disabling-preemption.patch
@@ -0,0 +1,296 @@
+From f2b7bfd175503ed854870b368aaa9e1be2159cab Mon Sep 17 00:00:00 2001
+From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Date: Wed, 14 Aug 2019 16:38:43 +0200
+Subject: [PATCH 290/347] dma-buf: Use seqlock_t instread disabling preemption
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz
+
+[ Upstream commit 240610aa31094f51f299f06eb8dae8d4cd8d4500 ]
+
+"dma reservation" disables preemption while acquiring the write access
+for "seqcount" and then may acquire a spinlock_t.
+
+Replace the seqcount with a seqlock_t which provides seqcount like
+semantic and lock for writer.
+
+Link: https://lkml.kernel.org/r/f410b429-db86-f81c-7c67-f563fa808b62@free.fr
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
+---
+ drivers/dma-buf/dma-buf.c | 8 ++--
+ drivers/dma-buf/reservation.c | 43 +++++++------------
+ .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 6 +--
+ drivers/gpu/drm/i915/i915_gem.c | 10 ++---
+ include/linux/reservation.h | 4 +-
+ 5 files changed, 29 insertions(+), 42 deletions(-)
+
+diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
+index 69842145c223..4c3ef46e7149 100644
+--- a/drivers/dma-buf/dma-buf.c
++++ b/drivers/dma-buf/dma-buf.c
+@@ -179,7 +179,7 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
+ return 0;
+
+ retry:
+- seq = read_seqcount_begin(&resv->seq);
++ seq = read_seqbegin(&resv->seq);
+ rcu_read_lock();
+
+ fobj = rcu_dereference(resv->fence);
+@@ -188,7 +188,7 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
+ else
+ shared_count = 0;
+ fence_excl = rcu_dereference(resv->fence_excl);
+- if (read_seqcount_retry(&resv->seq, seq)) {
++ if (read_seqretry(&resv->seq, seq)) {
+ rcu_read_unlock();
+ goto retry;
+ }
+@@ -1046,12 +1046,12 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
+
+ robj = buf_obj->resv;
+ while (true) {
+- seq = read_seqcount_begin(&robj->seq);
++ seq = read_seqbegin(&robj->seq);
+ rcu_read_lock();
+ fobj = rcu_dereference(robj->fence);
+ shared_count = fobj ? fobj->shared_count : 0;
+ fence = rcu_dereference(robj->fence_excl);
+- if (!read_seqcount_retry(&robj->seq, seq))
++ if (!read_seqretry(&robj->seq, seq))
+ break;
+ rcu_read_unlock();
+ }
+diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
+index 49ab09468ba1..f11d58492216 100644
+--- a/drivers/dma-buf/reservation.c
++++ b/drivers/dma-buf/reservation.c
+@@ -109,8 +109,7 @@ reservation_object_add_shared_inplace(struct reservation_object *obj,
+
+ dma_fence_get(fence);
+
+- preempt_disable();
+- write_seqcount_begin(&obj->seq);
++ write_seqlock(&obj->seq);
+
+ for (i = 0; i < fobj->shared_count; ++i) {
+ struct dma_fence *old_fence;
+@@ -121,8 +120,7 @@ reservation_object_add_shared_inplace(struct reservation_object *obj,
+ if (old_fence->context == fence->context) {
+ /* memory barrier is added by write_seqcount_begin */
+ RCU_INIT_POINTER(fobj->shared[i], fence);
+- write_seqcount_end(&obj->seq);
+- preempt_enable();
++ write_sequnlock(&obj->seq);
+
+ dma_fence_put(old_fence);
+ return;
+@@ -146,8 +144,7 @@ reservation_object_add_shared_inplace(struct reservation_object *obj,
+ fobj->shared_count++;
+ }
+
+- write_seqcount_end(&obj->seq);
+- preempt_enable();
++ write_sequnlock(&obj->seq);
+
+ dma_fence_put(signaled);
+ }
+@@ -191,15 +188,13 @@ reservation_object_add_shared_replace(struct reservation_object *obj,
+ fobj->shared_count++;
+
+ done:
+- preempt_disable();
+- write_seqcount_begin(&obj->seq);
++ write_seqlock(&obj->seq);
+ /*
+ * RCU_INIT_POINTER can be used here,
+ * seqcount provides the necessary barriers
+ */
+ RCU_INIT_POINTER(obj->fence, fobj);
+- write_seqcount_end(&obj->seq);
+- preempt_enable();
++ write_sequnlock(&obj->seq);
+
+ if (!old)
+ return;
+@@ -259,14 +254,11 @@ void reservation_object_add_excl_fence(struct reservation_object *obj,
+ if (fence)
+ dma_fence_get(fence);
+
+- preempt_disable();
+- write_seqcount_begin(&obj->seq);
+- /* write_seqcount_begin provides the necessary memory barrier */
++ write_seqlock(&obj->seq);
+ RCU_INIT_POINTER(obj->fence_excl, fence);
+ if (old)
+ old->shared_count = 0;
+- write_seqcount_end(&obj->seq);
+- preempt_enable();
++ write_sequnlock(&obj->seq);
+
+ /* inplace update, no shared fences */
+ while (i--)
+@@ -349,13 +341,10 @@ int reservation_object_copy_fences(struct reservation_object *dst,
+ src_list = reservation_object_get_list(dst);
+ old = reservation_object_get_excl(dst);
+
+- preempt_disable();
+- write_seqcount_begin(&dst->seq);
+- /* write_seqcount_begin provides the necessary memory barrier */
++ write_seqlock(&dst->seq);
+ RCU_INIT_POINTER(dst->fence_excl, new);
+ RCU_INIT_POINTER(dst->fence, dst_list);
+- write_seqcount_end(&dst->seq);
+- preempt_enable();
++ write_sequnlock(&dst->seq);
+
+ if (src_list)
+ kfree_rcu(src_list, rcu);
+@@ -396,7 +385,7 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj,
+ shared_count = i = 0;
+
+ rcu_read_lock();
+- seq = read_seqcount_begin(&obj->seq);
++ seq = read_seqbegin(&obj->seq);
+
+ fence_excl = rcu_dereference(obj->fence_excl);
+ if (fence_excl && !dma_fence_get_rcu(fence_excl))
+@@ -445,7 +434,7 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj,
+ }
+ }
+
+- if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
++ if (i != shared_count || read_seqretry(&obj->seq, seq)) {
+ while (i--)
+ dma_fence_put(shared[i]);
+ dma_fence_put(fence_excl);
+@@ -494,7 +483,7 @@ long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
+
+ retry:
+ shared_count = 0;
+- seq = read_seqcount_begin(&obj->seq);
++ seq = read_seqbegin(&obj->seq);
+ rcu_read_lock();
+ i = -1;
+
+@@ -541,7 +530,7 @@ long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
+
+ rcu_read_unlock();
+ if (fence) {
+- if (read_seqcount_retry(&obj->seq, seq)) {
++ if (read_seqretry(&obj->seq, seq)) {
+ dma_fence_put(fence);
+ goto retry;
+ }
+@@ -597,7 +586,7 @@ bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
+ retry:
+ ret = true;
+ shared_count = 0;
+- seq = read_seqcount_begin(&obj->seq);
++ seq = read_seqbegin(&obj->seq);
+
+ if (test_all) {
+ unsigned i;
+@@ -618,7 +607,7 @@ bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
+ break;
+ }
+
+- if (read_seqcount_retry(&obj->seq, seq))
++ if (read_seqretry(&obj->seq, seq))
+ goto retry;
+ }
+
+@@ -631,7 +620,7 @@ bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
+ if (ret < 0)
+ goto retry;
+
+- if (read_seqcount_retry(&obj->seq, seq))
++ if (read_seqretry(&obj->seq, seq))
+ goto retry;
+ }
+ }
+diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+index 4488aad64643..f22feb25eba9 100644
+--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
++++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+@@ -261,11 +261,9 @@ static int amdgpu_amdkfd_remove_eviction_fence(struct amdgpu_bo *bo,
+ }
+
+ /* Install the new fence list, seqcount provides the barriers */
+- preempt_disable();
+- write_seqcount_begin(&resv->seq);
++ write_seqlock(&resv->seq);
+ RCU_INIT_POINTER(resv->fence, new);
+- write_seqcount_end(&resv->seq);
+- preempt_enable();
++ write_sequnlock(&resv->seq);
+
+ /* Drop the references to the removed fences or move them to ef_list */
+ for (i = j, k = 0; i < old->shared_count; ++i) {
+diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
+index 5b0d6d8b3ab8..3fe4a1e93a1a 100644
+--- a/drivers/gpu/drm/i915/i915_gem.c
++++ b/drivers/gpu/drm/i915/i915_gem.c
+@@ -516,7 +516,7 @@ i915_gem_object_wait_reservation(struct reservation_object *resv,
+ long timeout,
+ struct intel_rps_client *rps_client)
+ {
+- unsigned int seq = __read_seqcount_begin(&resv->seq);
++ unsigned int seq = read_seqbegin(&resv->seq);
+ struct dma_fence *excl;
+ bool prune_fences = false;
+
+@@ -569,9 +569,9 @@ i915_gem_object_wait_reservation(struct reservation_object *resv,
+ * signaled and that the reservation object has not been changed (i.e.
+ * no new fences have been added).
+ */
+- if (prune_fences && !__read_seqcount_retry(&resv->seq, seq)) {
++ if (prune_fences && !read_seqretry(&resv->seq, seq)) {
+ if (reservation_object_trylock(resv)) {
+- if (!__read_seqcount_retry(&resv->seq, seq))
++ if (!read_seqretry(&resv->seq, seq))
+ reservation_object_add_excl_fence(resv, NULL);
+ reservation_object_unlock(resv);
+ }
+@@ -4696,7 +4696,7 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
+ *
+ */
+ retry:
+- seq = raw_read_seqcount(&obj->resv->seq);
++ seq = read_seqbegin(&obj->resv->seq);
+
+ /* Translate the exclusive fence to the READ *and* WRITE engine */
+ args->busy = busy_check_writer(rcu_dereference(obj->resv->fence_excl));
+@@ -4714,7 +4714,7 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
+ }
+ }
+
+- if (args->busy && read_seqcount_retry(&obj->resv->seq, seq))
++ if (args->busy && read_seqretry(&obj->resv->seq, seq))
+ goto retry;
+
+ err = 0;
+diff --git a/include/linux/reservation.h b/include/linux/reservation.h
+index 02166e815afb..0b31df1af698 100644
+--- a/include/linux/reservation.h
++++ b/include/linux/reservation.h
+@@ -72,7 +72,7 @@ struct reservation_object_list {
+ */
+ struct reservation_object {
+ struct ww_mutex lock;
+- seqcount_t seq;
++ seqlock_t seq;
+
+ struct dma_fence __rcu *fence_excl;
+ struct reservation_object_list __rcu *fence;
+@@ -92,7 +92,7 @@ reservation_object_init(struct reservation_object *obj)
+ {
+ ww_mutex_init(&obj->lock, &reservation_ww_class);
+
+- __seqcount_init(&obj->seq, reservation_seqcount_string, &reservation_seqcount_class);
++ seqlock_init(&obj->seq);
+ RCU_INIT_POINTER(obj->fence, NULL);
+ RCU_INIT_POINTER(obj->fence_excl, NULL);
+ obj->staged = NULL;
+--
+2.36.1
+
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-24 09:45:11 +0000