On Thu, 28 May 2020 at 11:24, Marek Szyprowski m.szyprowski@samsung.com wrote:
Hi Ulf,
On 28.05.2020 11:14, Ulf Hansson wrote:
On Wed, 27 May 2020 at 10:23, Tomi Valkeinen tomi.valkeinen@ti.com wrote:
Commit 9495b7e92f716ab2bd6814fab5e97ab4a39adfdd ("driver core: platform: Initialize dma_parms for platform devices") in v5.7-rc5 causes vb2_dma_contig_clear_max_seg_size() to kfree memory that was not allocated by vb2_dma_contig_set_max_seg_size().
The assumption in vb2_dma_contig_set_max_seg_size() seems to be that dev->dma_parms is always NULL when the driver is probed, and the case where dev->dma_parms has bee initialized by someone else than the driver (by calling vb2_dma_contig_set_max_seg_size) will cause a failure.
All the current users of these functions are platform devices, which now always have dma_parms set by the driver core. To fix the issue for v5.7, make vb2_dma_contig_set_max_seg_size() return an error if dma_parms is NULL to be on the safe side, and remove the kfree code from vb2_dma_contig_clear_max_seg_size().
For v5.8 we should remove the two functions and move the dma_set_max_seg_size() calls into the drivers.
Signed-off-by: Tomi Valkeinen tomi.valkeinen@ti.com Fixes: 9495b7e92f71 ("driver core: platform: Initialize dma_parms for platform devices") Cc: stable@vger.kernel.org
Thanks for fixing this!
However, as I tried to point out in v1, don't you need to care about drivers/media/platform/s5p-mfc/s5p_mfc.c, which allocates its own type of struct device (non-platform). No?
I will send a patch for the S5P MFC driver separately. It is not so critical, because the mentioned 2port memory case is not used on any board with the default exynos_defconfig from mainline. On Exynos4-based boards it is only used when IOMMU is disabled. It is mainly for S5PV210/S5PC110 boards, which are still not fully functional after conversion to device-tree.
Okay, makes sense to me. Feel free to add:
Reviewed-by: Ulf Hansson ulf.hansson@linaro.org
For the s5p_mfc issue, here's how I would have done it (just pick the code if you want).
diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc.c b/drivers/media/platform/s5p-mfc/s5p_mfc.c index 5c2a23b953a4..7acf2a03812d 100644 --- a/drivers/media/platform/s5p-mfc/s5p_mfc.c +++ b/drivers/media/platform/s5p-mfc/s5p_mfc.c @@ -1070,6 +1070,7 @@ static const struct v4l2_file_operations s5p_mfc_fops = { /* DMA memory related helper functions */ static void s5p_mfc_memdev_release(struct device *dev) { + kfree(dev->dma_parms); of_reserved_mem_device_release(dev); }
@@ -1090,6 +1091,10 @@ static struct device *s5p_mfc_alloc_memdev(struct device *dev, child->dma_mask = dev->dma_mask; child->release = s5p_mfc_memdev_release;
+ child->dma_parms = kzalloc(sizeof(*child->dma_parms), GFP_KERNEL); + if (!child->dma_parms) + goto err; + /* * The memdevs are not proper OF platform devices, so in order for them * to be treated as valid DMA masters we need a bit of a hack to force @@ -1105,6 +1110,7 @@ static struct device *s5p_mfc_alloc_memdev(struct device *dev, device_del(child); }
+err: put_device(child); return NULL; }
Kind regards Uffe