[src/trunk]: src/sys/external/bsd/drm2/dist/drm/i915 Handle uvm object refere...

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

details:   https://anonhg.NetBSD.org/src/rev/1e7e7df73f89
branches:  trunk
changeset: 993023:1e7e7df73f89
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Mon Aug 27 14:50:04 2018 +0000

description:
Handle uvm object reference counts in uvm_map more carefully.

Acquire a reference unconditionally first; then let uvm_map consume
it on success, and release it ourselves on failure.

As we did before -- acquiring a fresh reference on success -- another
thread might release the reference with a concurrent uvm_unmap before
we could acquire it back, thereby destroying the object.

XXX pullup-7 in part (i915_gem_fault)
XXX pullup-8 in part (i915_gem_fault)

diffstat:

 sys/external/bsd/drm2/dist/drm/i915/i915_cmd_parser.c       |  16 ++++++++----
 sys/external/bsd/drm2/dist/drm/i915/i915_gem.c              |   8 ++++--
 sys/external/bsd/drm2/dist/drm/i915/i915_gem_render_state.c |  12 +++++----
 3 files changed, 22 insertions(+), 14 deletions(-)

diffs (138 lines):

diff -r afb8df1dd268 -r 1e7e7df73f89 sys/external/bsd/drm2/dist/drm/i915/i915_cmd_parser.c
--- a/sys/external/bsd/drm2/dist/drm/i915/i915_cmd_parser.c     Mon Aug 27 14:49:39 2018 +0000
+++ b/sys/external/bsd/drm2/dist/drm/i915/i915_cmd_parser.c     Mon Aug 27 14:50:04 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: i915_cmd_parser.c,v 1.16 2018/08/27 14:46:38 riastradh Exp $   */
+/*     $NetBSD: i915_cmd_parser.c,v 1.17 2018/08/27 14:50:04 riastradh Exp $   */
 
 /*
  * Copyright © 2013 Intel Corporation
@@ -28,7 +28,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: i915_cmd_parser.c,v 1.16 2018/08/27 14:46:38 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: i915_cmd_parser.c,v 1.17 2018/08/27 14:50:04 riastradh Exp $");
 
 #include "i915_drv.h"
 
@@ -928,16 +928,18 @@
            - srcstart;
        vaddr_t srcva = 0;      /* hint */
 
+       /* Acquire a reference for uvm_map to consume.  */
+       uao_reference(src_obj->base.filp);
+
        /* XXX errno NetBSD->Linux */
        ret = -uvm_map(kernel_map, &srcva, srclen, src_obj->base.filp,
            srcstart, PAGE_SIZE, UVM_MAPFLAG(UVM_PROT_RW, UVM_PROT_RW,
                UVM_INH_NONE, UVM_ADV_SEQUENTIAL, UVM_FLAG_NOWAIT));
        if (ret) {
+               uao_detach(src_obj->base.filp);
                DRM_DEBUG_DRIVER("CMD: Failed to vmap batch: %d\n", ret);
                goto unpin_src;
        }
-       /* uvm_map consumes caller's reference on success.  */
-       uao_reference(src_obj->base.filp);
        src_base = (const void *)srcva;
 #else
        src_base = vmap_batch(src_obj, batch_start_offset, batch_len);
@@ -959,16 +961,18 @@
        const u32 dstlen = roundup(0 + batch_len, PAGE_SIZE) - dststart;
        vaddr_t dstva = 0;      /* hint */
 
+       /* Acquire a reference for uvm_map to consume.  */
+       uao_reference(dest_obj->base.filp);
+
        /* XXX errno NetBSD->Linux */
        ret = -uvm_map(kernel_map, &dstva, dstlen, dest_obj->base.filp,
            dststart, PAGE_SIZE, UVM_MAPFLAG(UVM_PROT_RW, UVM_PROT_RW,
                UVM_INH_NONE, UVM_ADV_SEQUENTIAL, UVM_FLAG_NOWAIT));
        if (ret) {
+               uao_detach(dest_obj->base.filp);
                DRM_DEBUG_DRIVER("CMD: Failed to vmap shadow batch: %d\n", ret);
                goto unmap_src;
        }
-       /* uvm_map consumes caller's reference on success.  */
-       uao_reference(dest_obj->base.filp);
        dst = (void *)dstva;
 #else
        dst = vmap_batch(dest_obj, 0, batch_len);
diff -r afb8df1dd268 -r 1e7e7df73f89 sys/external/bsd/drm2/dist/drm/i915/i915_gem.c
--- a/sys/external/bsd/drm2/dist/drm/i915/i915_gem.c    Mon Aug 27 14:49:39 2018 +0000
+++ b/sys/external/bsd/drm2/dist/drm/i915/i915_gem.c    Mon Aug 27 14:50:04 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: i915_gem.c,v 1.52 2018/08/27 14:47:02 riastradh Exp $  */
+/*     $NetBSD: i915_gem.c,v 1.53 2018/08/27 14:50:04 riastradh Exp $  */
 
 /*
  * Copyright © 2008-2015 Intel Corporation
@@ -28,7 +28,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: i915_gem.c,v 1.52 2018/08/27 14:47:02 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: i915_gem.c,v 1.53 2018/08/27 14:50:04 riastradh Exp $");
 
 #ifdef __NetBSD__
 #if 0                          /* XXX uvmhist option?  */
@@ -1956,6 +1956,8 @@
        }
 
 #ifdef __NetBSD__
+       /* Acquire a reference for uvm_map to consume.  */
+       uao_reference(obj->filp);
        addr = (*curproc->p_emul->e_vm_default_addr)(curproc,
            (vaddr_t)curproc->p_vmspace->vm_daddr, args->size,
            curproc->p_vmspace->vm_map.flags & VM_MAP_TOPDOWN);
@@ -1966,10 +1968,10 @@
                (VM_PROT_READ | VM_PROT_WRITE), UVM_INH_COPY, UVM_ADV_NORMAL,
                0));
        if (ret) {
+               uao_detach(obj->filp);
                drm_gem_object_unreference_unlocked(obj);
                return ret;
        }
-       uao_reference(obj->filp);
        drm_gem_object_unreference_unlocked(obj);
 #else
        addr = vm_mmap(obj->filp, 0, args->size,
diff -r afb8df1dd268 -r 1e7e7df73f89 sys/external/bsd/drm2/dist/drm/i915/i915_gem_render_state.c
--- a/sys/external/bsd/drm2/dist/drm/i915/i915_gem_render_state.c       Mon Aug 27 14:49:39 2018 +0000
+++ b/sys/external/bsd/drm2/dist/drm/i915/i915_gem_render_state.c       Mon Aug 27 14:50:04 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: i915_gem_render_state.c,v 1.8 2018/08/27 14:44:04 riastradh Exp $      */
+/*     $NetBSD: i915_gem_render_state.c,v 1.9 2018/08/27 14:50:04 riastradh Exp $      */
 
 /*
  * Copyright © 2014 Intel Corporation
@@ -28,7 +28,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: i915_gem_render_state.c,v 1.8 2018/08/27 14:44:04 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: i915_gem_render_state.c,v 1.9 2018/08/27 14:50:04 riastradh Exp $");
 
 #include "i915_drv.h"
 #include "intel_renderstate.h"
@@ -114,15 +114,17 @@
 
 #ifdef __NetBSD__
        CTASSERT(PAGE_SIZE == 4096);
+       /* Acquire a reference for uvm_map to consume.  */
+       uao_reference(so->obj->base.filp);
        kva = 0;                /* hint */
        /* XXX errno NetBSD->Linux */
        ret = -uvm_map(kernel_map, &kva, PAGE_SIZE, so->obj->base.filp, 0,
            sizeof(*d), UVM_MAPFLAG(UVM_PROT_W, UVM_PROT_W, UVM_INH_NONE,
                UVM_ADV_NORMAL, 0));
-       if (ret)
+       if (ret) {
+               uao_detach(so->obj->base.filp);
                return ret;
-       /* uvm_map consumes a reference on success.  */
-       uao_reference(so->obj->base.filp);
+       }
        d = (void *)kva;
 #else
        page = sg_page(so->obj->pages->sgl);