On Tue, 2012-09-18 at 15:45 -0400, Konrad Rzeszutek Wilk wrote: > On Tue, Sep 18, 2012 at 01:42:49PM -0600, Shuah Khan wrote: > > On Tue, 2012-09-18 at 15:34 +0200, Joerg Roedel wrote: > > > On Mon, Sep 17, 2012 at 04:45:15PM -0600, Shuah Khan wrote: > > > > Yeah. I will firm up my ideas a bit and summarize in a day or two. Would > > > > like to hear your ideas as well at that time, so we can pick the one > > > > that works the best. > > > > > > I think the best approach for this functionality is to add a flag to > > > 'struct dma_debug_entry' which tells whether the address has been > > > checked with dma_mapping error or not. On unmap or driver unload you can > > > then check for that flag and print a warning when an unchecked address > > > is detected. > > > > Was hoping to get comments from you as well. You are original author for > > this dam-debug module. > > > > Are you ok with the system wide and per device error counts I added? Any > > comments on the overall approach? > > > > The approach you suggested will cover the cases where drivers fail to > > check good map cases. We won't able to catch failed maps that get used > > without checks. Are you not concerned about these cases? These could > > cause a silent error with wild writes or could bring the system down. Or > > are you recommending changing the infrastructure to track failed maps as > > well? > > > > I am still pursuing a way to track failed map cases. I combined the flag > > idea with one of the ideas I am looking into. Details below: (if this > > sounds like a reasonable approach, I can do v2 patch and we can discuss > > the code) > > > > . Add new fields dma_map_errors, dma_map_errors_not_checked, > > dma_unmap_errors, iotlb_overflow_cnt, and flag to struct > > dma_debug_entry. Maybe flag is not even needed if > > dma_map_errors_not_checked can double as status. > > Not sure if you need the iotlb_overflow_cnt anymore. Just having > dma_map_errors_not_checked and the dma_map_errors > (which you can increment/decrement) would suffice. Unless you > were thinking to check that dma_map_errors == dma_unmap_errors and > if they != then produce a warning? Right. I wsn't thinking about that, but I get it. Don't need iotlb_overflow_cnt as it is included in the failed map count. What I meant was dma_map_errors_not_checked > 0 is same as the status this flag is intended to track can be a trigger for warn. But that is not going work because it will generate warnings as soon as dma_map_errors_not_checked becomes > 0 and stays that way. Need the flag. :) So dropping iotlb_overflow_cnt and keeping the status flag. -- Shuah -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
