[ Upstream commit e71695307114335be1ed912f4a347396c2ed0e69 ]
Resizing currently drops consumer lock. This can cause entries to be
reordered, which isn't good in itself. More importantly, consumer can
detect a false ring empty condition and block forever.
Further, nesting of consumer within producer lock is problematic for
tun, since it produces entries in a BH, which causes a lock order
reversal:
CPU0 CPU1
---- ----
consume:
lock(&(&r->consumer_lock)->rlock);
resize:
local_irq_disable();
lock(&(&r->producer_lock)->rlock);
lock(&(&r->consumer_lock)->rlock);
<Interrupt>
produce:
lock(&(&r->producer_lock)->rlock);
To fix, nest producer lock within consumer lock during resize,
and keep consumer lock during the whole swap operation.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: stable@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Michael S. Tsirkinauthored and Greg Kroah-Hartmancommited 2017-02-26 11:10:51 +01:00
Sometimes, we need support resizing multiple queues at once. This is
because it was not easy to recover to recover from a partial failure
of multiple queues resizing.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Michael S. Tsirkinauthored and David S. Millercommited 2016-07-01 05:32:17 -04:00
Sometimes, we need zero length ring. But current code will crash since
we don't do any check before accessing the ring. This patch fixes this.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Jason Wangauthored and David S. Millercommited 2016-07-01 05:32:16 -04:00
This adds ring resize support. Seems to be necessary as
users such as tun allow userspace control over queue size.
If resize is used, this costs us ability to peek at queue without
consumer lock - should not be a big deal as peek and consumer are
usually run on the same CPU.
If ring is made bigger, ring contents is preserved. If ring is made
smaller, extra pointers are passed to an optional destructor callback.
Cleanup function also gains destructor callback such that
all pointers in queue can be cleaned up.
This changes some APIs but we don't have any users yet,
so it won't break bisect.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Michael S. Tsirkinauthored and David S. Millercommited 2016-06-15 13:58:27 -07:00
A simple array based FIFO of pointers. Intended for net stack which
commonly has a single consumer/producer.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Michael S. Tsirkinauthored and David S. Millercommited 2016-06-15 13:57:21 -07:00
Michael S. Tsirkin
authored and
Greg Kroah-Hartman
commited 
David S. Miller
commited 
Jason Wang
authored and