Shareable bufmgr objects v4

Shareable bufmgr objects v4

[Lionel Landwerlin]

This is getting bigger than expected. Adding the locking that Chris
suggested on IRC.

Thanks for taking time to review Chris.

-
Lionel

[PATCH 1/4] atomic: add atomic_add_unless()

[Lionel Landwerlin]

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
---
 xf86atomic.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/xf86atomic.h b/xf86atomic.h
index db2f619..bc482c9 100644
--- a/xf86atomic.h
+++ b/xf86atomic.h
@@ -96,4 +96,13 @@ typedef struct { uint_t atomic; } atomic_t;
 #error libdrm requires atomic operations, please define them for your CPU/compiler.
 #endif
 
+static inline int atomic_add_unless(atomic_t *v, int add, int unless)
+{
+	int c, old;
+	c = atomic_read(v);
+	while (c != unless && (old = atomic_cmpxchg(v, c, c + add)) != c)
+		c = old;
+	return c == unless;
+}
+
 #endif
-- 
2.0.1

[PATCH 2/4] intel: make bufmgr_gem shareable from different API

[Lionel Landwerlin]

When using Mesa and LibVA in the same process, one would like to be
able bind buffers from the output of the decoder to a GL texture
through an EGLImage.

LibVA can reuse buffers allocated by Gbm through a file descriptor. It
will then wrap it into a drm_intel_bo with
drm_intel_bo_gem_create_from_prime().

The problem at the moment is that both library get a different
drm_intel_bufmgr object when they call drm_intel_bufmgr_gem_init()
even though they're using the same drm file descriptor. As a result,
instead of manipulating the same buffer object for a given file
descriptor, they get 2 different drm_intel_bo objects and 2 different
refcounts, leading one of the library to get errors from the kernel on
invalid BO when one of the 2 library is done with a shared buffer.

This patch modifies drm_intel_bufmgr_gem_init() so, given a file
descriptor, it will look for an already existing drm_intel_bufmgr
using the same file descriptor and return that object.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
---
 intel/intel_bufmgr_gem.c | 63 ++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 58 insertions(+), 5 deletions(-)

diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
index 0e1cb0d..1e2dd77 100644
--- a/intel/intel_bufmgr_gem.c
+++ b/intel/intel_bufmgr_gem.c
@@ -94,6 +94,8 @@ struct drm_intel_gem_bo_bucket {
 typedef struct _drm_intel_bufmgr_gem {
 	drm_intel_bufmgr bufmgr;
 
+	atomic_t refcount;
+
 	int fd;
 
 	int max_relocs;
@@ -111,6 +113,8 @@ typedef struct _drm_intel_bufmgr_gem {
 	int num_buckets;
 	time_t time;
 
+	drmMMListHead managers;
+
 	drmMMListHead named;
 	drmMMListHead vma_cache;
 	int vma_count, vma_open, vma_max;
@@ -3186,6 +3190,41 @@ drm_intel_bufmgr_gem_set_aub_annotations(drm_intel_bo *bo,
 	bo_gem->aub_annotation_count = count;
 }
 
+static pthread_mutex_t bufmgr_list_mutex = PTHREAD_MUTEX_INITIALIZER;
+static drmMMListHead bufmgr_list = { &bufmgr_list, &bufmgr_list };
+
+static drm_intel_bufmgr_gem *
+drm_intel_bufmgr_gem_find(int fd)
+{
+	drm_intel_bufmgr_gem *bufmgr_gem;
+
+	DRMLISTFOREACHENTRY(bufmgr_gem, &bufmgr_list, managers) {
+		if (bufmgr_gem->fd == fd) {
+			atomic_inc(&bufmgr_gem->refcount);
+			return bufmgr_gem;
+		}
+	}
+
+	return NULL;
+}
+
+static void
+drm_intel_bufmgr_gem_unref(drm_intel_bufmgr *bufmgr)
+{
+	drm_intel_bufmgr_gem *bufmgr_gem = (drm_intel_bufmgr_gem *)bufmgr;
+
+	if (atomic_add_unless(&bufmgr_gem->refcount, -1, 1)) {
+		pthread_mutex_lock(&bufmgr_list_mutex);
+
+		if (atomic_dec_and_test(&bufmgr_gem->refcount)) {
+			DRMLISTDEL(&bufmgr_gem->managers);
+			drm_intel_bufmgr_gem_destroy(bufmgr);
+		}
+
+		pthread_mutex_unlock(&bufmgr_list_mutex);
+	}
+}
+
 /**
  * Initializes the GEM buffer manager, which uses the kernel to allocate, map,
  * and manage map buffer objections.
@@ -3201,15 +3240,23 @@ drm_intel_bufmgr_gem_init(int fd, int batch_size)
 	int ret, tmp;
 	bool exec2 = false;
 
+	pthread_mutex_lock(&bufmgr_list_mutex);
+
+	bufmgr_gem = drm_intel_bufmgr_gem_find(fd);
+	if (bufmgr_gem)
+		goto exit;
+
 	bufmgr_gem = calloc(1, sizeof(*bufmgr_gem));
 	if (bufmgr_gem == NULL)
-		return NULL;
+		goto exit;
 
 	bufmgr_gem->fd = fd;
+	atomic_set(&bufmgr_gem->refcount, 1);
 
 	if (pthread_mutex_init(&bufmgr_gem->lock, NULL) != 0) {
 		free(bufmgr_gem);
-		return NULL;
+		bufmgr_gem = NULL;
+		goto exit;
 	}
 
 	ret = drmIoctl(bufmgr_gem->fd,
@@ -3246,7 +3293,8 @@ drm_intel_bufmgr_gem_init(int fd, int batch_size)
 		bufmgr_gem->gen = 8;
 	else {
 		free(bufmgr_gem);
-		return NULL;
+		bufmgr_gem = NULL;
+		goto exit;
 	}
 
 	if (IS_GEN3(bufmgr_gem->pci_device) &&
@@ -3357,7 +3405,7 @@ drm_intel_bufmgr_gem_init(int fd, int batch_size)
 		bufmgr_gem->bufmgr.bo_exec = drm_intel_gem_bo_exec;
 	bufmgr_gem->bufmgr.bo_busy = drm_intel_gem_bo_busy;
 	bufmgr_gem->bufmgr.bo_madvise = drm_intel_gem_bo_madvise;
-	bufmgr_gem->bufmgr.destroy = drm_intel_bufmgr_gem_destroy;
+	bufmgr_gem->bufmgr.destroy = drm_intel_bufmgr_gem_unref;
 	bufmgr_gem->bufmgr.debug = 0;
 	bufmgr_gem->bufmgr.check_aperture_space =
 	    drm_intel_gem_check_aperture_space;
@@ -3373,5 +3421,10 @@ drm_intel_bufmgr_gem_init(int fd, int batch_size)
 	DRMINITLISTHEAD(&bufmgr_gem->vma_cache);
 	bufmgr_gem->vma_max = -1; /* unlimited by default */
 
-	return &bufmgr_gem->bufmgr;
+	DRMLISTADD(&bufmgr_gem->managers, &bufmgr_list);
+
+exit:
+	pthread_mutex_unlock(&bufmgr_list_mutex);
+
+	return bufmgr_gem != NULL ? &bufmgr_gem->bufmgr : NULL;
 }
-- 
2.0.1

[PATCH 3/4] intel: make bo_unreference() thread safe

[Lionel Landwerlin]

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
---
 intel/intel_bufmgr_gem.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
index 1e2dd77..bf6745d 100644
--- a/intel/intel_bufmgr_gem.c
+++ b/intel/intel_bufmgr_gem.c
@@ -1157,7 +1157,8 @@ static void drm_intel_gem_bo_unreference(drm_intel_bo *bo)
 	drm_intel_bo_gem *bo_gem = (drm_intel_bo_gem *) bo;
 
 	assert(atomic_read(&bo_gem->refcount) > 0);
-	if (atomic_dec_and_test(&bo_gem->refcount)) {
+
+	if (atomic_add_unless(&bo_gem->refcount, -1, 1)) {
 		drm_intel_bufmgr_gem *bufmgr_gem =
 		    (drm_intel_bufmgr_gem *) bo->bufmgr;
 		struct timespec time;
@@ -1165,8 +1166,12 @@ static void drm_intel_gem_bo_unreference(drm_intel_bo *bo)
 		clock_gettime(CLOCK_MONOTONIC, &time);
 
 		pthread_mutex_lock(&bufmgr_gem->lock);
-		drm_intel_gem_bo_unreference_final(bo, time.tv_sec);
-		drm_intel_gem_cleanup_bo_cache(bufmgr_gem, time.tv_sec);
+
+		if (atomic_dec_and_test(&bo_gem->refcount)) {
+			drm_intel_gem_bo_unreference_final(bo, time.tv_sec);
+			drm_intel_gem_cleanup_bo_cache(bufmgr_gem, time.tv_sec);
+		}
+
 		pthread_mutex_unlock(&bufmgr_gem->lock);
 	}
 }
-- 
2.0.1

[PATCH 4/4] intel: make drm_intel_gem_bo_get_reloc_count() thread safe

[Lionel Landwerlin]

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
---
 intel/intel_bufmgr_gem.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
index bf6745d..4e34f75 100644
--- a/intel/intel_bufmgr_gem.c
+++ b/intel/intel_bufmgr_gem.c
@@ -1783,6 +1783,7 @@ drm_intel_gem_bo_get_reloc_count(drm_intel_bo *bo)
 drm_public void
 drm_intel_gem_bo_clear_relocs(drm_intel_bo *bo, int start)
 {
+	drm_intel_bufmgr_gem *bufmgr_gem = (drm_intel_bufmgr_gem *) bo->bufmgr;
 	drm_intel_bo_gem *bo_gem = (drm_intel_bo_gem *) bo;
 	int i;
 	struct timespec time;
@@ -1790,7 +1791,10 @@ drm_intel_gem_bo_clear_relocs(drm_intel_bo *bo, int start)
 	clock_gettime(CLOCK_MONOTONIC, &time);
 
 	assert(bo_gem->reloc_count >= start);
+
 	/* Unreference the cleared target buffers */
+	pthread_mutex_lock(&bufmgr_gem->lock);
+
 	for (i = start; i < bo_gem->reloc_count; i++) {
 		drm_intel_bo_gem *target_bo_gem = (drm_intel_bo_gem *) bo_gem->reloc_target_info[i].bo;
 		if (&target_bo_gem->bo != bo) {
@@ -1800,6 +1804,9 @@ drm_intel_gem_bo_clear_relocs(drm_intel_bo *bo, int start)
 		}
 	}
 	bo_gem->reloc_count = start;
+
+	pthread_mutex_unlock(&bufmgr_gem->lock);
+
 }
 
 /**
-- 
2.0.1

Re: Shareable bufmgr objects v4

[Chris Wilson]

On Fri, Sep 12, 2014 at 01:48:34PM +0100, Lionel Landwerlin wrote:
> This is getting bigger than expected. Adding the locking that Chris
> suggested on IRC.
> 
> Thanks for taking time to review Chris.

I'm happy with this series,
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre

Re: Shareable bufmgr objects v4

[Damien Lespiau]

On Mon, Sep 15, 2014 at 02:12:25PM +0100, Chris Wilson wrote:
> On Fri, Sep 12, 2014 at 01:48:34PM +0100, Lionel Landwerlin wrote:
> > This is getting bigger than expected. Adding the locking that Chris
> > suggested on IRC.
> > 
> > Thanks for taking time to review Chris.
> 
> I'm happy with this series,
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

Just landed the series for Lionel (who doesn't have access to this git
repo) then.

-- 
Damien