Messages in this thread | | | From | Logan Gunthorpe <> | Date | Fri, 15 Jun 2018 14:00:40 -0600 | Subject | Re: [PATCH 7/8] NTB: perf: Fix race condition when run with ntb_test |
| |
On 15/06/18 01:51 PM, Serge Semin wrote: > On Fri, Jun 08, 2018 at 06:08:18PM -0600, Logan Gunthorpe <logang@deltatee.com> wrote: >> When running ntb_test, the script tries to run the ntb_perf test >> immediately after probing the modules. Since adding multi-port support, >> this fails seeing the new initialization procedure in ntb_perf >> can not complete instantly. >> >> To fix this we add a completion which is waited on when a test is >> started. In this way, run can be written any time after the module is >> loaded and it will wait for the initialization to complete instead of >> sending an error. >> > > Hmm, this behavior is the feature of the driver and isn't a bug or race to be > fixed. ntb_perf driver returns -ENOLINK until the link is actually established, > when the memory windows are properly initialized so the test can be performed. > What do you think of leaving the algorithm as is, but instead to develop > the polling scheme in the ntb_test.sh script and break the script execution if > the link isn't established after sometime? At least we won't need to wait forever > in case if the peer hanged up or crashed while the NTB link negotiation algorithm > was in-progress.
I think polling is really ugly and doesn't really address solve the issue of waiting forever. It's pretty easy to interrupt out of the wait and provides a much better clue to whats going on than an error.
If we want to be more explicit, it would be pretty easy to start a timer in the bash script and use SIGALRM to exit if the link doesn't come up after 30 seconds or something.
Logan
| |