linux/net/sunrpc/xprtrdma
Tom Tucker c8237a5fce SVCRDMA: Check num_sge when setting LAST_CTXT bit
The RDMACTXT_F_LAST_CTXT bit was getting set incorrectly
when the last chunk in the read-list spanned multiple pages. This
resulted in a kernel panic when the wrong context was used to
build the RPC iovec page list.

RDMA_READ is used to fetch RPC data from the client for
NFS_WRITE requests. A scatter-gather is used to map the
advertised client side buffer to the server-side iovec and
associated page list.

WR contexts are used to convey which scatter-gather entries are
handled by each WR. When the write data is large, a single RPC may
require multiple RDMA_READ requests so the contexts for a single RPC
are chained together in a linked list. The last context in this list
is marked with a bit RDMACTXT_F_LAST_CTXT so that when this WR completes,
the CQ handler code can enqueue the RPC for processing.

The code in rdma_read_xdr was setting this bit on the last two
contexts on this list when the last read-list chunk spanned multiple
pages. This caused the svc_rdma_recvfrom logic to incorrectly build
the RPC and caused the kernel to crash because the second-to-last
context doesn't contain the iovec page list.

Modified the condition that sets this bit so that it correctly detects
the last context for the RPC.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Tested-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-03-26 11:24:19 -07:00
..
Makefile rdma: makefile 2008-02-01 16:42:14 -05:00
rpc_rdma.c SUNRPC: Fix an unnecessary implicit type cast in rpcrdma_count_chunks() 2008-01-30 02:05:42 -05:00
svc_rdma.c rdma: SVCRDMA Transport Module 2008-02-01 16:42:14 -05:00
svc_rdma_marshal.c rdma: ONCRPC RDMA protocol marshalling 2008-02-01 16:42:14 -05:00
svc_rdma_recvfrom.c SVCRDMA: Check num_sge when setting LAST_CTXT bit 2008-03-26 11:24:19 -07:00
svc_rdma_sendto.c SVCRDMA: Fix erroneous BUG_ON in send_write 2008-03-12 12:37:34 -07:00
svc_rdma_transport.c SVCRDMA: Add xprt refs to fix close/unmount crash 2008-03-12 12:37:34 -07:00
transport.c SUNRPC: Fix a nfs4 over rdma transport oops 2008-03-07 14:35:32 -05:00
verbs.c SUNRPC: Check a return result 2008-01-30 02:05:42 -05:00
xprt_rdma.h RPCRDMA: rpc rdma transport switch 2007-10-09 17:18:03 -04:00