On Tue, Oct 30, 2018 at 12:17:32PM -0400, Michael J. Ruhl wrote: > From: Michael J. Ruhl <michael.j.ruhl@xxxxxxxxx> > > commit a0e0cb82804a6a21d9067022c2dfdf80d11da429 upstream > > pq_update() can only be called in two places: from the completion > function when the complete (npkts) sequence of packets has been > submitted and processed, or from setup function if a subset of the > packets were submitted (i.e. the error path). > > Currently both paths can call pq_update() if an error occurrs. This > race will cause the n_req value to go negative, hanging file_close(), > or cause a crash by freeing the txlist more than once. > > Several variables are used to determine SDMA send state. Most of > these are unnecessary, and have code inspectible races between the > setup function and the completion function, in both the send path and > the error path. > > The request 'status' value can be set by the setup or by the > completion function. This is code inspectibly racy. Since the status > is not needed in the completion code or by the caller it has been > removed. > > The request 'done' value races between usage by the setup and the > completion function. The completion function does not need this. > When the number of processed packets matches npkts, it is done. > > The 'has_error' value races between usage of the setup and the > completion function. This can cause incorrect error handling and leave > the n_req in an incorrect value (i.e. negative). > > Simplify the code by removing all of the unneeded state checks and > variables. > > Clean up iovs node when it is freed. > > Eliminate race conditions in the error path: > > If all packets are submitted, the completion handler will set the > completion status correctly (ok or aborted). > > If all packets are not submitted, the caller must wait until the > submitted packets have completed, and then set the completion status. > > These two change eliminate the race condition in the error path. > > Cc: <stable@xxxxxxxxxxxxxxx> # 4.18.x+ Now applied, thanks. greg k-h
