d/freebsd-dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Change the xid for client side krpc over UDP to a global value.

Browse Source 
Without this patch, the xid used for the client side krpc requests over
UDP was initialized for each "connection". A "connection" for UDP is
rather sketchy and for the kernel NLM a new one is created every 2minutes.
A problem with client side interoperability with a Netapp server for the NLM
was reported and it is believed to be caused by reuse of the same xid.
Although this was never completely diagnosed by the reporter, I could see
how the same xid might get reused, since it is initialized to a value
based on the TOD clock every two minutes.
I suspect initializing the value for every "connection" was inherited from
userland library code, where having a global xid was not practical.
However, implementing a global "xid" for the kernel rpc is straightforward
and will ensure that an xid value is not reused for a long time. This
patch does that and is hoped it will fix the Netapp interoperability
problem.

PR:		245022
Reported by:	danny@cs.huji.ac.il
MFC after:	2 weeks
This commit is contained in:
Rick Macklem 2020-04-05 21:08:17 +00:00
parent f5339b097a
commit 9c2065607f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=359643
1 changed files with 10 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
sys/rpc/clnt_dg.c
View File

@ -94,6 +94,8 @@ static struct clnt_ops clnt_dg_ops = {
.cl_control = clnt_dg_control
};
static volatile uint32_t rpc_xid = 0;
/*
* A pending RPC request which awaits a reply. Requests which have
* received their reply will have cr_xid set to zero and cr_mrep to
@ -193,6 +195,7 @@ clnt_dg_create(
struct __rpc_sockinfo si;
XDR xdrs;
int error;
uint32_t newxid;
if (svcaddr == NULL) {
rpc_createerr.cf_stat = RPC_UNKNOWNADDR;
@ -245,8 +248,10 @@ clnt_dg_create(
cu->cu_sent = 0;
cu->cu_cwnd_wait = FALSE;
(void) getmicrotime(&now);
cu->cu_xid = __RPC_GETXID(&now);
call_msg.rm_xid = cu->cu_xid;
/* Clip at 28bits so that it will not wrap around. */
newxid = __RPC_GETXID(&now) & 0xfffffff;
atomic_cmpset_32(&rpc_xid, 0, newxid);
call_msg.rm_xid = atomic_fetchadd_32(&rpc_xid, 1);
call_msg.rm_call.cb_prog = program;
call_msg.rm_call.cb_vers = version;
xdrmem_create(&xdrs, cu->cu_mcallc, MCALL_MSG_SIZE, XDR_ENCODE);
@ -418,8 +423,7 @@ clnt_dg_call(
call_again:
mtx_assert(&cs->cs_lock, MA_OWNED);
cu->cu_xid++;
xid = cu->cu_xid;
xid = atomic_fetchadd_32(&rpc_xid, 1);
send_again:
mtx_unlock(&cs->cs_lock);
@ -865,13 +869,13 @@ clnt_dg_control(CLIENT *cl, u_int request, void *info)
(void) memcpy(&cu->cu_raddr, addr, addr->sa_len);
break;
case CLGET_XID:
*(uint32_t *)info = cu->cu_xid;
*(uint32_t *)info = atomic_load_32(&rpc_xid);
break;
case CLSET_XID:
/* This will set the xid of the NEXT call */
/* decrement by 1 as clnt_dg_call() increments once */
cu->cu_xid = *(uint32_t *)info - 1;
atomic_store_32(&rpc_xid, *(uint32_t *)info - 1);
break;
case CLGET_VERS: