From: Peter Hurley Date: Mon, 13 Jul 2015 00:50:49 +0000 (-0400) Subject: tty: Replace smp_rmb/smp_wmb with smp_load_acquire/smp_store_release X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=069f38b4983efaea92cbe7cc0cacc057af55739a;p=linux-beck.git tty: Replace smp_rmb/smp_wmb with smp_load_acquire/smp_store_release Clarify flip buffer producer/consumer operation; the use of smp_load_acquire() and smp_store_release() more clearly indicates which memory access requires a barrier. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c index 4cf263d7dffc..25ba5afbca13 100644 --- a/drivers/tty/tty_buffer.c +++ b/drivers/tty/tty_buffer.c @@ -291,12 +291,11 @@ static int __tty_buffer_request_room(struct tty_port *port, size_t size, n->flags = flags; buf->tail = n; b->commit = b->used; - /* paired w/ barrier in flush_to_ldisc(); ensures the + /* paired w/ acquire in flush_to_ldisc(); ensures the * latest commit value can be read before the head is * advanced to the next buffer */ - smp_wmb(); - b->next = n; + smp_store_release(&b->next, n); } else if (change) size = 0; else @@ -488,12 +487,11 @@ static void flush_to_ldisc(struct work_struct *work) if (atomic_read(&buf->priority)) break; - next = head->next; - /* paired w/ barrier in __tty_buffer_request_room(); + /* paired w/ release in __tty_buffer_request_room(); * ensures commit value read is not stale if the head * is advancing to the next buffer */ - smp_rmb(); + next = smp_load_acquire(&head->next); count = head->commit - head->read; if (!count) { if (next == NULL) {