On Wed, Jan 15, 2014 at 9:39 AM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Wed, Jan 15, 2014 at 12:40 AM, Russell King - ARM Linux > <linux@xxxxxxxxxxxxxxxx> wrote: >> On Wed, Jan 15, 2014 at 12:25:10AM +0100, Daniel Vetter wrote: >>> On Tue, Jan 14, 2014 at 06:14:06AM -0800, Ben Widawsky wrote: >>> > Both i915 and Armada had the exact same implementation. For an upcoming >>> > patch, I'd like to call this function from two different source files in >>> > i915, and having it available externally helps there too. >>> > >>> > While moving, add 'debugfs_' to the name in order to match the other drm >>> > debugfs helper functions. >>> > >>> > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx >>> > Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx >>> > Signed-off-by: Ben Widawsky <ben@xxxxxxxxxxxx> >>> >>> drm_debugfs_create_files in drm_debugfs.c has the almost same code again. >>> Now the problem here is that the interface is a bit botched up, since all >>> the users in i915 and armada actaully faile to clean up teh debugfs dentry >>> if drm_add_fake_info_node. >> >> That's not correct - armada does clean up these, I think you need to >> take a closer look at the code. >> >> We do this by setting node->info_ent to the file operations structure, >> which is a unique key to the file being registered. >> >> Upon failure to create the fake node, we appropriately call >> drm_debugfs_remove_files() with the first argument being a pointer to >> the file operations. This causes drm_debugfs_remove_files() to match >> the fake entry, call debugfs_remove() on the dentry, and remove the >> node from the list, and free the node structure we allocated. >> >> Upon driver teardown, we also call drm_debugfs_remove_files() but with >> each fops which should be registered, thus cleaning up each fake node >> which was created. >> >> So, Armada does clean up these entries properly. > > Indeed I've missed that and it's just i915 that botches this. I still > think the helper would be saner if it cleans up all its leftovers in > the failure case. Ok, now I've actually page all the stuff back in - if drm_add_fake_info_node fails we don't set up a drm_info_node structure and link it anywhere. Which means drm_debugfs_remove_files won't ever find it and hence can't possibly call debugfs_remove. Which means the debugfs dentry is leaked. So I think the semantics of that new debugfs helper should get fixed to also allocate and clean up the debugfs node. I agree that i915 is even worse since it doesn't bother to clean up any debugfs files at all in the failure case. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
