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The svc_rdma_recv_ctxt free list uses a lockless list to avoid the need for a spin lock in the fast path. llist_del_first(), which is used by svc_rdma_recv_ctxt_get(), requires serialization, however, when there are multiple list producers that are unserialized. I mistakenly thought there was only one caller of svc_rdma_recv_ctxt_get() (svc_rdma_refresh_recvs()), thus explicit serialization would not be necessary. But there is another caller: svc_rdma_bc_sendto(), and these two are not serialized against each other. I haven't seen ill effects that I could directly ascribe to a lack of serialization. It's just an observation based on code audit. When DMA-mapping before sending a Reply, the passed-in struct svc_rdma_recv_ctxt is used only for its write and reply PCLs. These are currently always empty in the backchannel case. So, instead of passing a full svc_rdma_recv_ctxt object to svc_rdma_map_reply_msg(), let's pass in just the Write and Reply PCLs. This change makes it unnecessary for the backchannel to acquire a dummy svc_rdma_recv_ctxt object when sending an RPC Call. The need for svc_rdma_recv_ctxt free list serialization is now completely avoided. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> |
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.. | ||
auth_gss | ||
xprtrdma | ||
.kunitconfig | ||
addr.c | ||
auth_null.c | ||
auth_tls.c | ||
auth_unix.c | ||
auth.c | ||
backchannel_rqst.c | ||
cache.c | ||
clnt.c | ||
debugfs.c | ||
fail.h | ||
Kconfig | ||
Makefile | ||
netns.h | ||
rpc_pipe.c | ||
rpcb_clnt.c | ||
sched.c | ||
socklib.c | ||
socklib.h | ||
stats.c | ||
sunrpc_syms.c | ||
sunrpc.h | ||
svc_xprt.c | ||
svc.c | ||
svcauth_unix.c | ||
svcauth.c | ||
svcsock.c | ||
sysctl.c | ||
sysfs.c | ||
sysfs.h | ||
timer.c | ||
xdr.c | ||
xprt.c | ||
xprtmultipath.c | ||
xprtsock.c |