On 07/26/2013 08:16 AM, Robert Jennings wrote: >>> > > + if ((spd->flags & SPLICE_F_MOVE) && >>> > > + !buf->offset && (buf->len == >>> > > PAGE_SIZE)) >>> > > + /* Can move page aligned buf */ >>> > > + zap_buf_page(useraddr); >>> > > buf->flags |= PIPE_BUF_FLAG_GIFT; >>> > > + } >> > >> > There isn't quite enough context here, but is it going to do this >> > zap_buf_page() very often? Seems a bit wasteful to do the up/down and >> > find_vma() every trip through the loop. > The call to zap_buf_page() is in a loop where each pipe buffer is being > processed, but in that loop we have a pipe_wait() where we schedule(). > So as things are structured I don't have the ability to hold mmap_sem > for multiple find_vma() calls.
You can hold a semaphore over a schedule(). :) You could also theoretically hold mmap_sem and only drop it on actual cases when you reschedule if you were afraid of holding mmap_sem for long periods of time (even though it's a read). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
