From 70cc77952efebf6722d483cb83cfb563ac9768db Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Fri, 29 Nov 2019 14:59:02 +0100 Subject: drm/panfrost: Fix a race in panfrost_ioctl_madvise() If 2 threads change the MADVISE property of the same BO in parallel we might end up with an shmem->madv value that's inconsistent with the presence of the BO in the shrinker list. The easiest solution to fix that is to protect the drm_gem_shmem_madvise() call with the shrinker lock. Fixes: 013b65101315 ("drm/panfrost: Add madvise and shrinker support") Cc: Signed-off-by: Boris Brezillon Reviewed-by: Steven Price Acked-by: Alyssa Rosenzweig Signed-off-by: Rob Herring Link: https://patchwork.freedesktop.org/patch/msgid/20191129135908.2439529-3-boris.brezillon@collabora.com --- drivers/gpu/drm/panfrost/panfrost_drv.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c index 9d086133a84e..8b8d6546cfac 100644 --- a/drivers/gpu/drm/panfrost/panfrost_drv.c +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c @@ -347,20 +347,19 @@ static int panfrost_ioctl_madvise(struct drm_device *dev, void *data, return -ENOENT; } + mutex_lock(&pfdev->shrinker_lock); args->retained = drm_gem_shmem_madvise(gem_obj, args->madv); if (args->retained) { struct panfrost_gem_object *bo = to_panfrost_bo(gem_obj); - mutex_lock(&pfdev->shrinker_lock); - if (args->madv == PANFROST_MADV_DONTNEED) - list_add_tail(&bo->base.madv_list, &pfdev->shrinker_list); + list_add_tail(&bo->base.madv_list, + &pfdev->shrinker_list); else if (args->madv == PANFROST_MADV_WILLNEED) list_del_init(&bo->base.madv_list); - - mutex_unlock(&pfdev->shrinker_lock); } + mutex_unlock(&pfdev->shrinker_lock); drm_gem_object_put_unlocked(gem_obj); return 0; -- cgit v1.2.3