Right now several architectures allow their set_memory_*() family of functions to fail, but callers may not be checking the return values. If set_memory_*() returns with an error, call-site assumptions may be infact wrong to assume that it would either succeed or not succeed at all. Ideally, the failure of set_memory_*() should be passed up the call stack, and callers should examine the failure and deal with it. Need to fix the callers and add the __must_check attribute. They also may not provide any level of atomicity, in the sense that the memory protections may be left incomplete on failure. This issue likely has a few steps on effects architectures: 1)Have all callers of set_memory_*() helpers check the return value. 2)Add __must_check to all set_memory_*() helpers so that new uses do not ignore the return value. 3)Add atomicity to the calls so that the memory protections aren't left in a partial state. This series is part of step 1. Make drm/radeon check the return value of set_memory_*(). Signed-off-by: Tianlin Li <tli@xxxxxxxxxxxxxxxx> --- v2: The hardware is too old to be tested on and the code cannot be simply removed from the kernel, so this is the solution for the short term. - Just print an error when something goes wrong - Remove patch 2. v1: https://lore.kernel.org/lkml/20200107192555.20606-1-tli@xxxxxxxxxxxxxxxx/ --- drivers/gpu/drm/radeon/radeon_gart.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/radeon/radeon_gart.c b/drivers/gpu/drm/radeon/radeon_gart.c index f178ba321715..a2cc864aa08d 100644 --- a/drivers/gpu/drm/radeon/radeon_gart.c +++ b/drivers/gpu/drm/radeon/radeon_gart.c @@ -80,8 +80,9 @@ int radeon_gart_table_ram_alloc(struct radeon_device *rdev) #ifdef CONFIG_X86 if (rdev->family == CHIP_RS400 || rdev->family == CHIP_RS480 || rdev->family == CHIP_RS690 || rdev->family == CHIP_RS740) { - set_memory_uc((unsigned long)ptr, - rdev->gart.table_size >> PAGE_SHIFT); + if (set_memory_uc((unsigned long)ptr, + rdev->gart.table_size >> PAGE_SHIFT)) + DRM_ERROR("set_memory_uc failed.\n"); } #endif rdev->gart.ptr = ptr; @@ -106,8 +107,9 @@ void radeon_gart_table_ram_free(struct radeon_device *rdev) #ifdef CONFIG_X86 if (rdev->family == CHIP_RS400 || rdev->family == CHIP_RS480 || rdev->family == CHIP_RS690 || rdev->family == CHIP_RS740) { - set_memory_wb((unsigned long)rdev->gart.ptr, - rdev->gart.table_size >> PAGE_SHIFT); + if (set_memory_wb((unsigned long)rdev->gart.ptr, + rdev->gart.table_size >> PAGE_SHIFT)) + DRM_ERROR("set_memory_wb failed.\n"); } #endif pci_free_consistent(rdev->pdev, rdev->gart.table_size, -- 2.17.1
