On Wed, Jan 15, 2014 at 12:08:19PM -0800, Ben Widawsky wrote: > On Wed, Jan 15, 2014 at 09:45:28AM +0100, Daniel Vetter wrote: > > 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 > > Perhaps I don't understand what you want here. The only failure path in > the fake entry creation does already call debugfs_remove. > > if (node == NULL) { > debugfs_remove(ent); > return -ENOMEM; > } > > So long as the function succeeds, the node will be findable and removable. Oh dear, I didn't see that. Still stand by my opinion though that we should shovel the debugfs_create_file into the helper - callers allocating something and then the helper freeing it (but only if it fails) is rather funky semantics. -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
