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SUNRPC: Don't hold the transport lock across socket copy operations

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Instead add a mechanism to ensure that the request doesn't disappear
from underneath us while copying from the socket. We do this by
preventing xprt_release() from freeing the XDR buffers until the
flag RPC_TASK_MSG_RECV has been cleared from the request.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Trond Myklebust 2017-08-13 10:03:59 -04:00
parent 2ce209c42c
commit 729749bb8d
4 changed files with 65 additions and 5 deletions
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2
include/linux/sunrpc/sched.h
View File

@ -139,6 +139,8 @@ struct rpc_task_setup {
#define RPC_TASK_RUNNING 0
#define RPC_TASK_QUEUED 1
#define RPC_TASK_ACTIVE 2
#define RPC_TASK_MSG_RECV 3
#define RPC_TASK_MSG_RECV_WAIT 4
#define RPC_IS_RUNNING(t) test_bit(RPC_TASK_RUNNING, &(t)->tk_runstate)
#define rpc_set_running(t) set_bit(RPC_TASK_RUNNING, &(t)->tk_runstate)

2
include/linux/sunrpc/xprt.h
View File

@ -372,6 +372,8 @@ void xprt_write_space(struct rpc_xprt *xprt);
void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result);
struct rpc_rqst * xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid);
void xprt_complete_rqst(struct rpc_task *task, int copied);
void xprt_pin_rqst(struct rpc_rqst *req);
void xprt_unpin_rqst(struct rpc_rqst *req);
void xprt_release_rqst_cong(struct rpc_task *task);
void xprt_disconnect_done(struct rpc_xprt *xprt);
void xprt_force_disconnect(struct rpc_xprt *xprt);

43
net/sunrpc/xprt.c
View File

@ -844,6 +844,48 @@ struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
}
EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
/**
* xprt_pin_rqst - Pin a request on the transport receive list
* @req: Request to pin
*
* Caller must ensure this is atomic with the call to xprt_lookup_rqst()
* so should be holding the xprt transport lock.
*/
void xprt_pin_rqst(struct rpc_rqst *req)
{
set_bit(RPC_TASK_MSG_RECV, &req->rq_task->tk_runstate);
}
/**
* xprt_unpin_rqst - Unpin a request on the transport receive list
* @req: Request to pin
*
* Caller should be holding the xprt transport lock.
*/
void xprt_unpin_rqst(struct rpc_rqst *req)
{
struct rpc_task *task = req->rq_task;
clear_bit(RPC_TASK_MSG_RECV, &task->tk_runstate);
if (test_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate))
wake_up_bit(&task->tk_runstate, RPC_TASK_MSG_RECV);
}
static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
__must_hold(&req->rq_xprt->transport_lock)
{
struct rpc_task *task = req->rq_task;
if (task && test_bit(RPC_TASK_MSG_RECV, &task->tk_runstate)) {
spin_unlock_bh(&req->rq_xprt->transport_lock);
set_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate);
wait_on_bit(&task->tk_runstate, RPC_TASK_MSG_RECV,
TASK_UNINTERRUPTIBLE);
clear_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate);
spin_lock_bh(&req->rq_xprt->transport_lock);
}
}
static void xprt_update_rtt(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
@ -1295,6 +1337,7 @@ void xprt_release(struct rpc_task *task)
list_del(&req->rq_list);
xprt->last_used = jiffies;
xprt_schedule_autodisconnect(xprt);
xprt_wait_on_pinned_rqst(req);
spin_unlock_bh(&xprt->transport_lock);
if (req->rq_buffer)
xprt->ops->buf_free(task);

23
net/sunrpc/xprtsock.c
View File

@ -973,6 +973,8 @@ static void xs_local_data_read_skb(struct rpc_xprt *xprt,
rovr = xprt_lookup_rqst(xprt, *xp);
if (!rovr)
goto out_unlock;
xprt_pin_rqst(rovr);
spin_unlock_bh(&xprt->transport_lock);
task = rovr->rq_task;
copied = rovr->rq_private_buf.buflen;
@ -981,11 +983,14 @@ static void xs_local_data_read_skb(struct rpc_xprt *xprt,
if (xs_local_copy_to_xdr(&rovr->rq_private_buf, skb)) {
dprintk("RPC: sk_buff copy failed\n");
goto out_unlock;
spin_lock_bh(&xprt->transport_lock);
goto out_unpin;
}
spin_lock_bh(&xprt->transport_lock);
xprt_complete_rqst(task, copied);
out_unpin:
xprt_unpin_rqst(rovr);
out_unlock:
spin_unlock_bh(&xprt->transport_lock);
}
@ -1054,6 +1059,8 @@ static void xs_udp_data_read_skb(struct rpc_xprt *xprt,
rovr = xprt_lookup_rqst(xprt, *xp);
if (!rovr)
goto out_unlock;
xprt_pin_rqst(rovr);
spin_unlock_bh(&xprt->transport_lock);
task = rovr->rq_task;
if ((copied = rovr->rq_private_buf.buflen) > repsize)
@ -1062,14 +1069,17 @@ static void xs_udp_data_read_skb(struct rpc_xprt *xprt,
/* Suck it into the iovec, verify checksum if not done by hw. */
if (csum_partial_copy_to_xdr(&rovr->rq_private_buf, skb)) {
__UDPX_INC_STATS(sk, UDP_MIB_INERRORS);
goto out_unlock;
spin_lock_bh(&xprt->transport_lock);
goto out_unpin;
}
__UDPX_INC_STATS(sk, UDP_MIB_INDATAGRAMS);
spin_lock_bh(&xprt->transport_lock);
xprt_adjust_cwnd(xprt, task, copied);
xprt_complete_rqst(task, copied);
out_unpin:
xprt_unpin_rqst(rovr);
out_unlock:
spin_unlock_bh(&xprt->transport_lock);
}
@ -1351,12 +1361,15 @@ static inline int xs_tcp_read_reply(struct rpc_xprt *xprt,
spin_unlock_bh(&xprt->transport_lock);
return -1;
}
xprt_pin_rqst(req);
spin_unlock_bh(&xprt->transport_lock);
xs_tcp_read_common(xprt, desc, req);
spin_lock_bh(&xprt->transport_lock);
if (!(transport->tcp_flags & TCP_RCV_COPY_DATA))
xprt_complete_rqst(req->rq_task, transport->tcp_copied);
xprt_unpin_rqst(req);
spin_unlock_bh(&xprt->transport_lock);
return 0;
}