On Mon, Jan 10, 2022 at 01:09:02PM +0000, Pai G, Sunil wrote: > Hi Bruce, Kevin > > This patch seems to have uncovered a bug in the driver. > On applying, the idxd_burst_capacity API seems to return 0 for cases even > when there are batch descriptors and ring space available. > Seems like there is a wraparound missing when calculating the descriptor ring > space, causing this behavior. > > Below change seems to fix the issue. > > @@ -483,7 +496,7 @@ idxd_burst_capacity(const void *dev_private, uint16_t > vchan __rte_unused) > /* For descriptors, check for wrap-around on write but not read */ > if (idxd->ids_returned > write_idx) > write_idx += idxd->desc_ring_mask + 1; > - used_space = write_idx - idxd->ids_returned; > + used_space = (write_idx - idxd->ids_returned)&idxd->desc_ring_mask; > > <snipped> > > Could we include this fix in the current patch ? > Hi Sunil,
what values for the write_idx and ids_returned vars give this error, and how does masking help? I'd expect masking to increase the number of times the function returns zero, rather than decreasing it. /Bruce
