Hi,I have a few comments that are not really something for this patch. I'll comment it here anyway to have them posted.
Am 06.11.22 um 00:27 schrieb Dmitry Osipenko:
DMA-buf core has its own refcounting of vmaps, use it instead of drm-shmem counting. This change prepares drm-shmem for addition of memory shrinker support where drm-shmem will use a single dma-buf reservation lock for all operations performed over dma-bufs. Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx> --- drivers/gpu/drm/drm_gem_shmem_helper.c | 35 +++++++++++++++----------- 1 file changed, 20 insertions(+), 15 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 35138f8a375c..801033b48893 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -293,24 +293,22 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct drm_gem_object *obj = &shmem->base; int ret = 0;- if (shmem->vmap_use_count++ > 0) {- iosys_map_set_vaddr(map, shmem->vaddr); - return 0; - } - if (obj->import_attach) {
We have a number of such branches in various memory managers. At some point we should think about something like a GEM DMA-BUF object (or at least some helpers) that represents an imported buffer. Such a ting might be useful to avoid the duplication and branching that's going on here and in other functions.
ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
if (!ret) {
if (WARN_ON(map->is_iomem)) {
I think it's OK to drop this test for is_iomem. It was useful when we did not distinguish between I/O and system memory in most of our helpers. But that should have been resolved by now and whatever code still depends on it should be updated accordingly. All helpers use iosys_map functionality to access the memory.
dma_buf_vunmap(obj->import_attach->dmabuf, map); - ret = -EIO; - goto err_put_pages; + return -EIO; } - shmem->vaddr = map->vaddr;
To resolve the is_iomap issue, we'd have to store vaddr as struct iosysm_map value.
} } else { pgprot_t prot = PAGE_KERNEL;+ if (shmem->vmap_use_count++ > 0) {+ iosys_map_set_vaddr(map, shmem->vaddr); + return 0; + } + ret = drm_gem_shmem_get_pages(shmem); if (ret) goto err_zero_use; @@ -376,15 +374,15 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem, { struct drm_gem_object *obj = &shmem->base;- if (WARN_ON_ONCE(!shmem->vmap_use_count))- return; - - if (--shmem->vmap_use_count > 0) - return; - if (obj->import_attach) { dma_buf_vunmap(obj->import_attach->dmabuf, map); } else { + if (WARN_ON_ONCE(!shmem->vmap_use_count)) + return; + + if (--shmem->vmap_use_count > 0) + return; + vunmap(shmem->vaddr); drm_gem_shmem_put_pages(shmem); } @@ -646,7 +644,14 @@ void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem, struct drm_printer *p, unsigned int indent) { drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count); - drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count); + + if (shmem->base.import_attach) + drm_printf_indent(p, indent, "vmap_use_count=%u\n", + shmem->base.dma_buf->vmapping_counter); + else + drm_printf_indent(p, indent, "vmap_use_count=%u\n", + shmem->vmap_use_count); +
Here's another case where a GEM DMA-BUF object might become helpful. Best regards Thomas
drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr); } EXPORT_SYMBOL(drm_gem_shmem_print_info);
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
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