attempt to fix race in kms_swrast_dri.so affecting kwin.

0001-kms-dri-add-mutex-lock-around-map-unmap.patch

@@ -0,0 +1,116 @@
+From 9cfb950bc704d4f984f5a39838634c73a5765bac Mon Sep 17 00:00:00 2001
+From: Dave Airlie <airlied@redhat.com>
+Date: Thu, 14 Jul 2022 10:34:04 +1000
+Subject: [PATCH] kms/dri: add mutex lock around map/unmap
+
+this can get called from multiple threads with the recent llvmpipe
+overlapping rendering changes, so make sure to lock around the
+map/unmapping so they can't race.
+
+This should fixes some crashes seen with kwin.
+---
+ .../winsys/sw/kms-dri/kms_dri_sw_winsys.c     | 20 +++++++++++++++++--
+ 1 file changed, 18 insertions(+), 2 deletions(-)
+
+diff --git a/src/gallium/winsys/sw/kms-dri/kms_dri_sw_winsys.c b/src/gallium/winsys/sw/kms-dri/kms_dri_sw_winsys.c
+index a26ff0ffe35..aa1257acea9 100644
+--- a/src/gallium/winsys/sw/kms-dri/kms_dri_sw_winsys.c
++++ b/src/gallium/winsys/sw/kms-dri/kms_dri_sw_winsys.c
+@@ -55,6 +55,8 @@
+ #include "frontend/drm_driver.h"
+ #include "kms_dri_sw_winsys.h"
+ 
++#include "util/simple_mtx.h"
++
+ #ifdef DEBUG
+ #define DEBUG_PRINT(msg, ...) fprintf(stderr, msg, __VA_ARGS__)
+ #else
+@@ -86,6 +88,7 @@ struct kms_sw_displaytarget
+    int map_count;
+    struct list_head link;
+    struct list_head planes;
++   mtx_t map_lock;
+ };
+ 
+ struct kms_sw_winsys
+@@ -183,6 +186,8 @@ kms_sw_displaytarget_create(struct sw_winsys *ws,
+ 
+    kms_sw_dt->format = format;
+ 
++   mtx_init(&kms_sw_dt->map_lock, mtx_plain);
++
+    memset(&create_req, 0, sizeof(create_req));
+    create_req.bpp = util_format_get_blocksizebits(format);
+    create_req.width = width;
+@@ -239,6 +244,7 @@ kms_sw_displaytarget_destroy(struct sw_winsys *ws,
+ 
+    list_del(&kms_sw_dt->link);
+ 
++   mtx_destroy(&kms_sw_dt->map_lock);
+    DEBUG_PRINT("KMS-DEBUG: destroyed buffer %u\n", kms_sw_dt->handle);
+ 
+    struct kms_sw_plane *tmp;
+@@ -260,11 +266,12 @@ kms_sw_displaytarget_map(struct sw_winsys *ws,
+    struct drm_mode_map_dumb map_req;
+    int prot, ret;
+ 
++   mtx_lock(&kms_sw_dt->map_lock);
+    memset(&map_req, 0, sizeof map_req);
+    map_req.handle = kms_sw_dt->handle;
+    ret = drmIoctl(kms_sw->fd, DRM_IOCTL_MODE_MAP_DUMB, &map_req);
+    if (ret)
+-      return NULL;
++      goto fail_locked;
+ 
+    prot = (flags == PIPE_MAP_READ) ? PROT_READ : (PROT_READ | PROT_WRITE);
+    void **ptr = (flags == PIPE_MAP_READ) ? &kms_sw_dt->ro_mapped : &kms_sw_dt->mapped;
+@@ -272,7 +279,7 @@ kms_sw_displaytarget_map(struct sw_winsys *ws,
+       void *tmp = mmap(NULL, kms_sw_dt->size, prot, MAP_SHARED,
+                        kms_sw->fd, map_req.offset);
+       if (tmp == MAP_FAILED)
+-         return NULL;
++         goto fail_locked;
+       *ptr = tmp;
+    }
+ 
+@@ -281,7 +288,12 @@ kms_sw_displaytarget_map(struct sw_winsys *ws,
+ 
+    kms_sw_dt->map_count++;
+ 
++   mtx_unlock(&kms_sw_dt->map_lock);
++
+    return *ptr + plane->offset;
++fail_locked:
++   mtx_unlock(&kms_sw_dt->map_lock);
++   return NULL;
+ }
+ 
+ static struct kms_sw_displaytarget *
+@@ -363,13 +375,16 @@ kms_sw_displaytarget_unmap(struct sw_winsys *ws,
+    struct kms_sw_plane *plane = kms_sw_plane(dt);
+    struct kms_sw_displaytarget *kms_sw_dt = plane->dt;
+ 
++   mtx_lock(&kms_sw_dt->map_lock);
+    if (!kms_sw_dt->map_count)  {
+       DEBUG_PRINT("KMS-DEBUG: ignore duplicated unmap %u", kms_sw_dt->handle);
++      mtx_unlock(&kms_sw_dt->map_lock);
+       return;
+    }
+    kms_sw_dt->map_count--;
+    if (kms_sw_dt->map_count) {
+       DEBUG_PRINT("KMS-DEBUG: ignore unmap for busy buffer %u", kms_sw_dt->handle);
++      mtx_unlock(&kms_sw_dt->map_lock);
+       return;
+    }
+ 
+@@ -384,6 +399,7 @@ kms_sw_displaytarget_unmap(struct sw_winsys *ws,
+       munmap(kms_sw_dt->ro_mapped, kms_sw_dt->size);
+       kms_sw_dt->ro_mapped = MAP_FAILED;
+    }
++   mtx_unlock(&kms_sw_dt->map_lock);
+ }
+ 
+ static struct sw_displaytarget *
+-- 
+2.37.0
+

mesa.spec

@@ -74,6 +74,9 @@ Patch0006: 0004-Revert-nouveau-no-modifier-the-invalid-modifier.patch
 Patch0007: 0005-Revert-nouveau-Use-DRM_FORMAT_MOD_NVIDIA_BLOCK_LINEA.patch
 Patch0008: 0006-Revert-nouveau-Stash-supported-sector-layout-in-scre.patch
 
+# attempt to fix race in kms_swrast_dri.so affecting kwin.
+Patch0010: 0001-kms-dri-add-mutex-lock-around-map-unmap.patch
+
 BuildRequires:  meson >= 0.45
 BuildRequires:  gcc
 BuildRequires:  gcc-c++