Commit 4dc51b32 authored Apr 16, 2008 by Eli Cohen Committed by Roland Dreier Apr 16, 2008

IB/mlx4: Fix race when detaching a QP from a multicast group



When detaching the last QP from an MCG entry, we need to make
sure that at any time, there will be no entry with zero number of
QPs which is linked to the list of the MCGs of the corresponding
hash index.  So don't write back the MCG entry if we are removing the
last QP; just unlink the entry.

Also, remove an unnecessary MCG read when attaching a QP requires
allocation of a new entry in the AMGM.

Signed-off-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

parent c83b5b1c

drivers/net/mlx4/mcg.c

+3 −9

Original line number	Diff line number	Diff line
		@@ -190,10 +190,6 @@ int mlx4_multicast_attach(struct mlx4_dev dev, struct mlx4_qp qp, u8 gid[16])
		}
		index += dev->caps.num_mgms;

		err = mlx4_READ_MCG(dev, index, mailbox);
		if (err)
		goto out;

		memset(mgm, 0, sizeof *mgm);
		memcpy(mgm->gid, gid, 16);
		}
		@@ -301,12 +297,10 @@ int mlx4_multicast_detach(struct mlx4_dev dev, struct mlx4_qp qp, u8 gid[16])
		mgm->qp[loc] = mgm->qp[i - 1];
		mgm->qp[i - 1] = 0;

		if (i != 1) {
		err = mlx4_WRITE_MCG(dev, index, mailbox);
		if (err)
		goto out;

		if (i != 1)
		goto out;
		}

		if (prev == -1) {
		/* Remove entry from MGM */

Admin message