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| author | Peter Hurley <peter@hurleysoftware.com> | 2015-07-12 20:50:49 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-07-23 18:23:56 -0700 |
| commit | 069f38b4983efaea92cbe7cc0cacc057af55739a (patch) | |
| tree | e6799228488e07a49b7a90bbdbab74ad246efdca /drivers/tty/tty_buffer.c | |
| parent | e5eb517dd80e4da3055895f8aa3547c2bfd5e675 (diff) | |
| download | lwn-069f38b4983efaea92cbe7cc0cacc057af55739a.tar.gz lwn-069f38b4983efaea92cbe7cc0cacc057af55739a.zip | |
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 <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/tty_buffer.c')
| -rw-r--r-- | drivers/tty/tty_buffer.c | 10 |
1 files changed, 4 insertions, 6 deletions
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) { |