[ofa-general] [PATCH 2 of 5] libmthca: zero context struct at allocation time (prep for additional context ops)

[Jack Morgenstein]

The ibv_context structure will be getting additional ops,
to be added at the end of the structure (and not as part of
the existing ibv_context_ops structure).

Reason: ibv_context_ops is declared directly as a member of ibv_context,
and not as a pointer.  Binaries compiled with previous libibverbs versions
will not be backwards compatible if we add new operations to ibv_context_ops,
since fields following the ops structure will move.

To enable adding new operations at the end of the existing ibv_context struct,
all driver libraries MUST zero their context structure at allocation time, so
that new ops will be NULL by default.

Signed-off-by: Jack Morgenstein <jackm at dev.mellanox.co.il>

diff --git a/src/mthca.c b/src/mthca.c
index 0f7e953..702e821 100644
--- a/src/mthca.c
+++ b/src/mthca.c
@@ -142,6 +142,7 @@ static struct ibv_context *mthca_alloc_context(struct ibv_device *ibdev, int cmd
 	if (!context)
 		return NULL;
 
+	memset(context, 0, sizeof *context);
 	context->ibv_ctx.cmd_fd = cmd_fd;
 
 	if (ibv_cmd_get_context(&context->ibv_ctx, &cmd, sizeof cmd,