On Mon, 26 Jan 2015 21:46:58 +0000 Al Viro <v...@zeniv.linux.org.uk> wrote:
> On Mon, Jan 26, 2015 at 03:42:59PM -0500, Steven Rostedt wrote: > > On Mon, 26 Jan 2015 19:30:49 +0000 > > Al Viro <v...@zeniv.linux.org.uk> wrote: > > > > > You are still fighting an inconvenient API, but now it's not debugfs one - > > > it's your copy thereof. Why not give your instances/ an inode_operations > > > of its own? One with ->mkdir() and ->rmdir(), leaving all other > > > directories > > > as-is. That way you don't need the secondary methods at all. And sure, > > > debugfs_create_dir() grabs ->i_mutex on parent, making you drop that in > > > your ->mkdir() if you want to call it. But now you are not talking to it > > > - > > > just to your own code, where you are free to change the calling > > > conventions, > > > making it caller's responsibility to get that ->i_mutex. The same goes > > > for > > > the rmdir side... > > > > The vfs layer grabs the i_mutex, which needs to be dropped. > > What for? Just keep it through your instance_mkdir/instance_rmdir and be > done with that. Sure, it means that you need variants of file/directory > creation/removal primitives that would assume that parent is already locked > by caller (and would leave unlocking to the caller as well). So add them... I originally had this, but the issue isn't with i_mutex only. The instance_mkdir and instance_rmdir need to grab trace_types_lock. This is also held when calling into tracefs. That is, we can not hold i_mutex and take trace_types_lock. trace_types_lock needs to be held with the creation or destruction of events, which is what mkdir an rmdir do. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
