[src/trunk]: src/sys/external/bsd/drm2/linux drm: Use atomic_store_release/lo...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/7b39e33c76fa
branches:  trunk
changeset: 1028735:7b39e33c76fa
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sun Dec 19 11:53:33 2021 +0000

description:
drm: Use atomic_store_release/load_consume in linux_dma_resv.c.

At least, for robj->fence and robj->fence_excl.  Need to review
list->shared_count and list->shared[i] too.

diffstat:

 sys/external/bsd/drm2/linux/linux_dma_resv.c |  76 ++++++---------------------
 1 files changed, 17 insertions(+), 59 deletions(-)

diffs (195 lines):

diff -r f27635436948 -r 7b39e33c76fa sys/external/bsd/drm2/linux/linux_dma_resv.c
--- a/sys/external/bsd/drm2/linux/linux_dma_resv.c      Sun Dec 19 11:53:26 2021 +0000
+++ b/sys/external/bsd/drm2/linux/linux_dma_resv.c      Sun Dec 19 11:53:33 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: linux_dma_resv.c,v 1.5 2021/12/19 11:52:55 riastradh Exp $     */
+/*     $NetBSD: linux_dma_resv.c,v 1.6 2021/12/19 11:53:33 riastradh Exp $     */
 
 /*-
  * Copyright (c) 2018 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_dma_resv.c,v 1.5 2021/12/19 11:52:55 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_dma_resv.c,v 1.6 2021/12/19 11:53:33 riastradh Exp $");
 
 #include <sys/param.h>
 #include <sys/poll.h>
@@ -464,7 +464,7 @@
        dma_resv_write_begin(robj, &ticket);
 
        /* Replace the fence and zero the shared count.  */
-       robj->fence_excl = fence;
+       atomic_store_release(&robj->fence_excl, fence);
        if (old_list)
                old_list->shared_count = 0;
 
@@ -573,7 +573,7 @@
                dma_resv_write_begin(robj, &ticket);
 
                /* Replace the list.  */
-               robj->fence = prealloc;
+               atomic_store_release(&robj->fence, prealloc);
                robj->robj_prealloc = NULL;
 
                /* Commit the update.  */
@@ -629,11 +629,7 @@
        dma_resv_read_begin(robj, &ticket);
 
        /* If there is a shared list, grab it.  */
-       list = robj->fence;
-       __insn_barrier();
-       if (list) {
-               /* Make sure the content of the list has been published.  */
-               membar_datadep_consumer();
+       if ((list = atomic_load_consume(&robj->fence)) != NULL) {
 
                /* Check whether we have a buffer.  */
                if (shared == NULL) {
@@ -642,7 +638,6 @@
                         * one without waiting.
                         */
                        shared_alloc = list->shared_max;
-                       __insn_barrier();
                        shared = kcalloc(shared_alloc, sizeof(shared[0]),
                            GFP_NOWAIT);
                        if (shared == NULL) {
@@ -665,7 +660,6 @@
                         * out and wait to allocate a bigger one.
                         */
                        shared_alloc = list->shared_max;
-                       __insn_barrier();
                        rcu_read_unlock();
                        kfree(shared);
                        shared = kcalloc(shared_alloc, sizeof(shared[0]),
@@ -686,12 +680,7 @@
        }
 
        /* If there is an exclusive fence, grab it.  */
-       fence = robj->fence_excl;
-       __insn_barrier();
-       if (fence) {
-               /* Make sure the content of the fence has been published.  */
-               membar_datadep_consumer();
-       }
+       fence = atomic_load_consume(&robj->fence_excl);
 
        /*
         * We are done reading from robj and list.  Validate our
@@ -770,11 +759,7 @@
        dma_resv_read_begin(src_robj, &read_ticket);
 
        /* Get the shared list.  */
-       src_list = src_robj->fence;
-       __insn_barrier();
-       if (src_list) {
-               /* Make sure the content of the list has been published.  */
-               membar_datadep_consumer();
+       if ((src_list = atomic_load_consume(&src_robj->fence)) != NULL) {
 
                /* Find out how long it is.  */
                shared_count = src_list->shared_count;
@@ -808,11 +793,7 @@
        }
 
        /* Get the exclusive fence.  */
-       fence = src_robj->fence_excl;
-       __insn_barrier();
-       if (fence != NULL) {
-               /* Make sure the content of the fence has been published.  */
-               membar_datadep_consumer();
+       if ((fence = atomic_load_consume(&src_robj->fence_excl)) != NULL) {
 
                /*
                 * Make sure we saw a consistent snapshot of the fence.
@@ -853,8 +834,9 @@
        dma_resv_write_begin(dst_robj, &write_ticket);
 
        /* Replace the fences.  */
-       dst_robj->fence = dst_list;
-       dst_robj->fence_excl = fence;
+       membar_exit();
+       atomic_store_relaxed(&dst_robj->fence, dst_list);
+       atomic_store_relaxed(&dst_robj->fence_excl, fence);
 
        /* Commit the update.  */
        dma_resv_write_commit(dst_robj, &write_ticket);
@@ -918,11 +900,7 @@
        /* If shared is requested and there is a shared list, test it.  */
        if (!shared)
                goto excl;
-       list = robj->fence;
-       __insn_barrier();
-       if (list) {
-               /* Make sure the content of the list has been published.  */
-               membar_datadep_consumer();
+       if ((list = atomic_load_consume(&robj->fence)) != NULL) {
 
                /* Find out how long it is.  */
                shared_count = list->shared_count;
@@ -953,11 +931,7 @@
 
 excl:
        /* If there is an exclusive fence, test it.  */
-       fence = robj->fence_excl;
-       __insn_barrier();
-       if (fence) {
-               /* Make sure the content of the fence has been published.  */
-               membar_datadep_consumer();
+       if ((fence = atomic_load_consume(&robj->fence_excl)) != NULL) {
 
                /*
                 * Make sure we saw a consistent snapshot of the fence.
@@ -1022,11 +996,7 @@
        /* If shared is requested and there is a shared list, wait on it.  */
        if (!shared)
                goto excl;
-       list = robj->fence;
-       __insn_barrier();
-       if (list) {
-               /* Make sure the content of the list has been published.  */
-               membar_datadep_consumer();
+       if ((list = atomic_load_consume(&robj->fence)) != NULL) {
 
                /* Find out how long it is.  */
                shared_count = list->shared_count;
@@ -1056,11 +1026,7 @@
 
 excl:
        /* If there is an exclusive fence, test it.  */
-       fence = robj->fence_excl;
-       __insn_barrier();
-       if (fence) {
-               /* Make sure the content of the fence has been published.  */
-               membar_datadep_consumer();
+       if ((fence = atomic_load_consume(&robj->fence_excl)) != NULL) {
 
                /*
                 * Make sure we saw a consistent snapshot of the fence.
@@ -1202,11 +1168,7 @@
        /* If we want to wait for all fences, get the shared list.  */
        if (!(events & POLLOUT))
                goto excl;
-       list = robj->fence;
-       __insn_barrier();
-       if (list) do {
-               /* Make sure the content of the list has been published.  */
-               membar_datadep_consumer();
+       if ((list = atomic_load_consume(&robj->fence)) != NULL) do {
 
                /* Find out how long it is.  */
                shared_count = list->shared_count;
@@ -1277,11 +1239,7 @@
 
 excl:
        /* We always wait for at least the exclusive fence, so get it.  */
-       fence = robj->fence_excl;
-       __insn_barrier();
-       if (fence) do {
-               /* Make sure the content of the fence has been published.  */
-               membar_datadep_consumer();
+       if ((fence = atomic_load_consume(&robj->fence_excl)) != NULL) do {
 
                /*
                 * Make sure we saw a consistent snapshot of the fence.