On Tue, Mar 27, 2018 at 12:27 AM, Jason Gunthorpe <jgg@xxxxxxxx> wrote: > On Tue, Mar 27, 2018 at 09:01:57AM +1100, Benjamin Herrenschmidt wrote: >> On Mon, 2018-03-26 at 17:46 -0400, Sinan Kaya wrote: > > I even see patches adding wmb() based on actual observed memory > corruption during testing on Intel: > > https://patchwork.kernel.org/patch/10177207/ > > So you think all of this is unnecessary and writel is totally strongly > ordered, even on multi-socket Intel? This example adds a wmb() between two writes to a coherent DMA area, it is definitely required there. I'm pretty sure I've never seen any bug reports pointing to a missing wmb() between memory and MMIO write accesses, but if you remember seeing them in the list, maybe you can look again for some evidence of something going wrong on x86 without it? Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
