On Friday 11 June 2004 7:01 pm, Alasdair G Kergon wrote: > On Thu, Jun 10, 2004 at 05:30:31PM +0000, Kevin Corry wrote: > > And while we're in there hacking up that routine, we should probably add > > proper error handling instead of just using BUG_ON() in the event someone > > tries to read from multiple regions. > > At present, the num_regions parameter is not allowed to exceed 1 when > reading. If it does, that should show up clearly as a coding error. > Prefer WARN_ON() ? In general I'm not a big fan of BUG() statements, and I try to only use them to indicate some unexpected error internal to a driver. In the current context of dm-io only being used by DM modules that we write, I might agree that the BUG_ON() is sufficient. But I really see dm-io as something that should eventually become a generic block-layer service, not specific to just DM. In that event, potentially any driver could be calling the routines, and as such it makes sense to me to validate the arguments to prevent invalid uses. In that context, a BUG_ON() seems heavy-handed. A WARN_ON() by itself seems insufficient since it will let the routine keep executing, which we obviously don't want. However, it might be worth adding an error message and stack-dump (like you get with WARN_ON) in that situation in addition to returning an error. -- Kevin Corry kevcorry@xxxxxxxxxx http://evms.sourceforge.net/
