On Fri, May 30, 2014 at 5:47 PM, John Baldwin <j...@freebsd.org> wrote: > On Friday, May 30, 2014 11:39:24 am Attilio Rao wrote: >> On Fri, May 30, 2014 at 5:03 PM, John Baldwin <j...@freebsd.org> wrote: >> > On Friday, May 30, 2014 10:54:06 am Attilio Rao wrote: >> >> On Tue, May 27, 2014 at 11:31 PM, Scott Long <sco...@freebsd.org> wrote: >> >> > Author: scottl >> >> > Date: Tue May 27 21:31:11 2014 >> >> > New Revision: 266775 >> >> > URL: http://svnweb.freebsd.org/changeset/base/266775 >> >> > >> >> > Log: >> >> > Eliminate the fake contig_dmamap and replace it with a new flag, >> >> > BUS_DMA_KMEM_ALLOC. They serve the same purpose, but using the flag >> >> > means that the map can be NULL again, which in turn enables >> >> > significant >> >> > optimizations for the common case of no bouncing. >> >> >> >> While I think this is in general a good idea, unfortunately our >> >> drivers do so many dumb things when freeing DMA allocated buffers that >> >> having a NULL map is going to cause some "turbolence" and make such >> >> bugs more visible. >> >> An example is with ATA, where I think this fix is needed: >> >> http://www.freebsd.org/~attilio/dmamem_free-ata.patch >> >> >> >> Otherwise, what can happen with bounce buffers, is that the allocated >> >> memory via contig malloc was not going to be freed anytime. >> >> >> >> I tried to look around and I found questionable (read broken) code in >> >> basically every driver which allocates DMA buffers, so I really don't >> >> feel I want to fix the majority of our drivers. I just think such >> >> paths are not excercised enough to be seen in practice often or the >> >> bugs just get unnoticed. >> > >> > Eh, many maps for static allocations were already NULL and have been for a >> > long time. This is nothign new. Plus, the diff you posted has a bug >> > regardless of explicitly destroying a map created by bus_dmamem_alloc(). >> >> Did you notice that I *removed* the destroy not *added*? > > Yes, my point was that that bug in the original code you are fixing was there > regardless of Scott's change.
And when I did say something different? I don't understand what's the point of your messages, besides showing that you didn't read correctly my patch. Attilio -- Peace can only be achieved by understanding - A. Einstein _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
