297 lines
9.7 KiB
Diff
297 lines
9.7 KiB
Diff
From fc310572745c255840931c77c058698ed0ee811c Mon Sep 17 00:00:00 2001
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Wed, 14 Aug 2019 16:38:43 +0200
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Subject: [PATCH 291/325] dma-buf: Use seqlock_t instread disabling preemption
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.115-rt48.tar.xz
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[ Upstream commit 240610aa31094f51f299f06eb8dae8d4cd8d4500 ]
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"dma reservation" disables preemption while acquiring the write access
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for "seqcount" and then may acquire a spinlock_t.
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Replace the seqcount with a seqlock_t which provides seqcount like
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semantic and lock for writer.
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Link: https://lkml.kernel.org/r/f410b429-db86-f81c-7c67-f563fa808b62@free.fr
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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---
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drivers/dma-buf/dma-buf.c | 8 ++--
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drivers/dma-buf/reservation.c | 43 +++++++------------
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.../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 6 +--
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drivers/gpu/drm/i915/i915_gem.c | 10 ++---
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include/linux/reservation.h | 4 +-
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5 files changed, 29 insertions(+), 42 deletions(-)
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diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
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index 69842145c223..4c3ef46e7149 100644
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--- a/drivers/dma-buf/dma-buf.c
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+++ b/drivers/dma-buf/dma-buf.c
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@@ -179,7 +179,7 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
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return 0;
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retry:
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- seq = read_seqcount_begin(&resv->seq);
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+ seq = read_seqbegin(&resv->seq);
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rcu_read_lock();
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fobj = rcu_dereference(resv->fence);
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@@ -188,7 +188,7 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
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else
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shared_count = 0;
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fence_excl = rcu_dereference(resv->fence_excl);
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- if (read_seqcount_retry(&resv->seq, seq)) {
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+ if (read_seqretry(&resv->seq, seq)) {
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rcu_read_unlock();
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goto retry;
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}
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@@ -1046,12 +1046,12 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
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robj = buf_obj->resv;
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while (true) {
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- seq = read_seqcount_begin(&robj->seq);
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+ seq = read_seqbegin(&robj->seq);
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rcu_read_lock();
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fobj = rcu_dereference(robj->fence);
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shared_count = fobj ? fobj->shared_count : 0;
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fence = rcu_dereference(robj->fence_excl);
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- if (!read_seqcount_retry(&robj->seq, seq))
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+ if (!read_seqretry(&robj->seq, seq))
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break;
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rcu_read_unlock();
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}
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diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
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index 49ab09468ba1..f11d58492216 100644
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--- a/drivers/dma-buf/reservation.c
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+++ b/drivers/dma-buf/reservation.c
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@@ -109,8 +109,7 @@ reservation_object_add_shared_inplace(struct reservation_object *obj,
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dma_fence_get(fence);
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- preempt_disable();
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- write_seqcount_begin(&obj->seq);
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+ write_seqlock(&obj->seq);
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for (i = 0; i < fobj->shared_count; ++i) {
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struct dma_fence *old_fence;
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@@ -121,8 +120,7 @@ reservation_object_add_shared_inplace(struct reservation_object *obj,
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if (old_fence->context == fence->context) {
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/* memory barrier is added by write_seqcount_begin */
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RCU_INIT_POINTER(fobj->shared[i], fence);
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- write_seqcount_end(&obj->seq);
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- preempt_enable();
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+ write_sequnlock(&obj->seq);
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dma_fence_put(old_fence);
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return;
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@@ -146,8 +144,7 @@ reservation_object_add_shared_inplace(struct reservation_object *obj,
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fobj->shared_count++;
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}
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- write_seqcount_end(&obj->seq);
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- preempt_enable();
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+ write_sequnlock(&obj->seq);
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dma_fence_put(signaled);
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}
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@@ -191,15 +188,13 @@ reservation_object_add_shared_replace(struct reservation_object *obj,
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fobj->shared_count++;
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done:
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- preempt_disable();
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- write_seqcount_begin(&obj->seq);
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+ write_seqlock(&obj->seq);
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/*
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* RCU_INIT_POINTER can be used here,
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* seqcount provides the necessary barriers
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*/
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RCU_INIT_POINTER(obj->fence, fobj);
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- write_seqcount_end(&obj->seq);
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- preempt_enable();
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+ write_sequnlock(&obj->seq);
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if (!old)
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return;
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@@ -259,14 +254,11 @@ void reservation_object_add_excl_fence(struct reservation_object *obj,
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if (fence)
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dma_fence_get(fence);
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- preempt_disable();
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- write_seqcount_begin(&obj->seq);
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- /* write_seqcount_begin provides the necessary memory barrier */
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+ write_seqlock(&obj->seq);
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RCU_INIT_POINTER(obj->fence_excl, fence);
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if (old)
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old->shared_count = 0;
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- write_seqcount_end(&obj->seq);
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- preempt_enable();
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+ write_sequnlock(&obj->seq);
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/* inplace update, no shared fences */
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while (i--)
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@@ -349,13 +341,10 @@ int reservation_object_copy_fences(struct reservation_object *dst,
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src_list = reservation_object_get_list(dst);
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old = reservation_object_get_excl(dst);
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- preempt_disable();
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- write_seqcount_begin(&dst->seq);
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- /* write_seqcount_begin provides the necessary memory barrier */
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+ write_seqlock(&dst->seq);
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RCU_INIT_POINTER(dst->fence_excl, new);
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RCU_INIT_POINTER(dst->fence, dst_list);
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- write_seqcount_end(&dst->seq);
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- preempt_enable();
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+ write_sequnlock(&dst->seq);
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if (src_list)
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kfree_rcu(src_list, rcu);
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@@ -396,7 +385,7 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj,
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shared_count = i = 0;
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rcu_read_lock();
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- seq = read_seqcount_begin(&obj->seq);
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+ seq = read_seqbegin(&obj->seq);
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fence_excl = rcu_dereference(obj->fence_excl);
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if (fence_excl && !dma_fence_get_rcu(fence_excl))
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@@ -445,7 +434,7 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj,
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}
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}
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- if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
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+ if (i != shared_count || read_seqretry(&obj->seq, seq)) {
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while (i--)
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dma_fence_put(shared[i]);
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dma_fence_put(fence_excl);
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@@ -494,7 +483,7 @@ long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
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retry:
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shared_count = 0;
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- seq = read_seqcount_begin(&obj->seq);
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+ seq = read_seqbegin(&obj->seq);
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rcu_read_lock();
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i = -1;
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@@ -541,7 +530,7 @@ long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
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rcu_read_unlock();
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if (fence) {
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- if (read_seqcount_retry(&obj->seq, seq)) {
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+ if (read_seqretry(&obj->seq, seq)) {
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dma_fence_put(fence);
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goto retry;
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}
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@@ -597,7 +586,7 @@ bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
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retry:
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ret = true;
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shared_count = 0;
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- seq = read_seqcount_begin(&obj->seq);
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+ seq = read_seqbegin(&obj->seq);
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if (test_all) {
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unsigned i;
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@@ -618,7 +607,7 @@ bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
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break;
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}
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- if (read_seqcount_retry(&obj->seq, seq))
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+ if (read_seqretry(&obj->seq, seq))
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goto retry;
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}
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@@ -631,7 +620,7 @@ bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
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if (ret < 0)
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goto retry;
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- if (read_seqcount_retry(&obj->seq, seq))
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+ if (read_seqretry(&obj->seq, seq))
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goto retry;
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}
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}
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diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
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index f92597c292fe..10c675850aac 100644
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--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
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+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
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@@ -261,11 +261,9 @@ static int amdgpu_amdkfd_remove_eviction_fence(struct amdgpu_bo *bo,
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}
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/* Install the new fence list, seqcount provides the barriers */
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- preempt_disable();
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- write_seqcount_begin(&resv->seq);
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+ write_seqlock(&resv->seq);
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RCU_INIT_POINTER(resv->fence, new);
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- write_seqcount_end(&resv->seq);
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- preempt_enable();
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+ write_sequnlock(&resv->seq);
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/* Drop the references to the removed fences or move them to ef_list */
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for (i = j, k = 0; i < old->shared_count; ++i) {
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diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
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index c7d05ac7af3c..d484e79316bf 100644
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--- a/drivers/gpu/drm/i915/i915_gem.c
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+++ b/drivers/gpu/drm/i915/i915_gem.c
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@@ -516,7 +516,7 @@ i915_gem_object_wait_reservation(struct reservation_object *resv,
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long timeout,
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struct intel_rps_client *rps_client)
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{
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- unsigned int seq = __read_seqcount_begin(&resv->seq);
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+ unsigned int seq = read_seqbegin(&resv->seq);
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struct dma_fence *excl;
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bool prune_fences = false;
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@@ -569,9 +569,9 @@ i915_gem_object_wait_reservation(struct reservation_object *resv,
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* signaled and that the reservation object has not been changed (i.e.
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* no new fences have been added).
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*/
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- if (prune_fences && !__read_seqcount_retry(&resv->seq, seq)) {
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+ if (prune_fences && !read_seqretry(&resv->seq, seq)) {
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if (reservation_object_trylock(resv)) {
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- if (!__read_seqcount_retry(&resv->seq, seq))
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+ if (!read_seqretry(&resv->seq, seq))
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reservation_object_add_excl_fence(resv, NULL);
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reservation_object_unlock(resv);
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}
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@@ -4615,7 +4615,7 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
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*
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*/
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retry:
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- seq = raw_read_seqcount(&obj->resv->seq);
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+ seq = read_seqbegin(&obj->resv->seq);
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/* Translate the exclusive fence to the READ *and* WRITE engine */
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args->busy = busy_check_writer(rcu_dereference(obj->resv->fence_excl));
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@@ -4633,7 +4633,7 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
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}
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}
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- if (args->busy && read_seqcount_retry(&obj->resv->seq, seq))
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+ if (args->busy && read_seqretry(&obj->resv->seq, seq))
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goto retry;
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err = 0;
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diff --git a/include/linux/reservation.h b/include/linux/reservation.h
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index 02166e815afb..0b31df1af698 100644
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--- a/include/linux/reservation.h
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+++ b/include/linux/reservation.h
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@@ -72,7 +72,7 @@ struct reservation_object_list {
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*/
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struct reservation_object {
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struct ww_mutex lock;
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- seqcount_t seq;
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+ seqlock_t seq;
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struct dma_fence __rcu *fence_excl;
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struct reservation_object_list __rcu *fence;
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@@ -92,7 +92,7 @@ reservation_object_init(struct reservation_object *obj)
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{
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ww_mutex_init(&obj->lock, &reservation_ww_class);
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- __seqcount_init(&obj->seq, reservation_seqcount_string, &reservation_seqcount_class);
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+ seqlock_init(&obj->seq);
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RCU_INIT_POINTER(obj->fence, NULL);
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RCU_INIT_POINTER(obj->fence_excl, NULL);
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obj->staged = NULL;
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--
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2.25.1
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