Andrew and Ingo: As discussed earlier, the following patches change the representation used for the return values from queue_work(), schedule_work(), and related routines. It turned out these functions were used in ~800 places, and in ~90% of them the return value was ignored! This is perhaps understandble, because the only way these functions can fail is if their work_struct argument is uninitialized or already in use. (Whether it's robust for callers to depend on this behavior remaining unchanged into the indefinite future is more questionable.) So I took a short cut which allowed most of the usages to remain as they are. queue_work(), schedule_work(), and their friends still exist and do what they did before, but now they return void. In addition, they call WARN_ON if the submission fails; this seems safer than letting the failure go silently unnoticed. However there is a risk to using WARN_ON: In at least one place (drivers/char/vt.c) a call to schedule_work() is _expected_ to fail! The driver doesn't care whether or not the work_struct is already queued, so long as the callback occurs eventually. This amounts to relying on undocumented behavior; I added an explanatory comment but it's not clear what the right approach is. The same thing may happen in other places. Perhaps the WARN_ON lines shouldn't be added. Keeping the old routine names may complicate the changeover slightly, but it isn't dangerous. The compiler will flag as an error any attempt to call the old routine names expecting a non-void return value. In place of the original routines are add_work_to_q(), add_work(), and so on. They return int values, but now the values are 0 for success and -EBUSY for failure instead of 1 for success and 0 for failure. The relatively small number of places that did check the return values have been updated to use the new routines. (Incidentally, rpc_make_runnable() in net/sunrpc/sched.c checked the return value in the wrong way -- which is now the correct way. So the patch _does_ qualify as a bug fix.) There were four functions acting as wrappers around queue_work or queue_delayed_work: fc_queue_work() and fc_queue_devloss_work() in drivers/scsi/scsi_transport_fc.c, scsi_queue_work() in drivers/scsi/hosts.c, and kblockd_schedule_work() in block/ll_rw_blk.c. These functions passed the return value from queue_work back to their callers, which might have made things awkward -- except that none of the callers check the return value! So I changed all these routines to return void instead of int. Finally, included is a patch which adds a new chapter to Documentation/CodingStyle. It explains how to decide between returning a 1/0 code vs. a 0/-Exxx code for success/failure, and it speaks for itself. Alan Stern - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
