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Message-Id: <1205260300-19127-2-git-send-email-bfields@citi.umich.edu>
Date: Tue, 11 Mar 2008 14:31:39 -0400
From: "J. Bruce Fields" <bfields@...i.umich.edu>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
Tom Tucker <tom@...ngridcomputing.com>,
"J. Bruce Fields" <bfields@...i.umich.edu>
Subject: [PATCH 1/2] SVCRDMA: Add xprt refs to fix close/unmount crash
From: Tom Tucker <tom@...ngridcomputing.com>
RDMA connection shutdown on an SMP machine can cause a kernel crash due
to the transport close path racing with the I/O tasklet.
Additional transport references were added as follows:
- A reference when on the DTO Q to avoid having the transport
deleted while queued for I/O.
- A reference while there is a QP able to generate events.
- A reference until the DISCONNECTED event is received on the CM ID
Signed-off-by: Tom Tucker <tom@...ngridcomputing.com>
Signed-off-by: J. Bruce Fields <bfields@...i.umich.edu>
---
net/sunrpc/xprtrdma/svc_rdma_transport.c | 96 ++++++++++++++++++------------
1 files changed, 58 insertions(+), 38 deletions(-)
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index f09444c..16fd3f6 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -54,7 +54,6 @@ static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
int flags);
static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt);
static void svc_rdma_release_rqst(struct svc_rqst *);
-static void rdma_destroy_xprt(struct svcxprt_rdma *xprt);
static void dto_tasklet_func(unsigned long data);
static void svc_rdma_detach(struct svc_xprt *xprt);
static void svc_rdma_free(struct svc_xprt *xprt);
@@ -247,6 +246,7 @@ static void dto_tasklet_func(unsigned long data)
sq_cq_reap(xprt);
}
+ svc_xprt_put(&xprt->sc_xprt);
spin_lock_irqsave(&dto_lock, flags);
}
spin_unlock_irqrestore(&dto_lock, flags);
@@ -275,8 +275,10 @@ static void rq_comp_handler(struct ib_cq *cq, void *cq_context)
* add it
*/
spin_lock_irqsave(&dto_lock, flags);
- if (list_empty(&xprt->sc_dto_q))
+ if (list_empty(&xprt->sc_dto_q)) {
+ svc_xprt_get(&xprt->sc_xprt);
list_add_tail(&xprt->sc_dto_q, &dto_xprt_q);
+ }
spin_unlock_irqrestore(&dto_lock, flags);
/* Tasklet does all the work to avoid irqsave locks. */
@@ -386,8 +388,10 @@ static void sq_comp_handler(struct ib_cq *cq, void *cq_context)
* add it
*/
spin_lock_irqsave(&dto_lock, flags);
- if (list_empty(&xprt->sc_dto_q))
+ if (list_empty(&xprt->sc_dto_q)) {
+ svc_xprt_get(&xprt->sc_xprt);
list_add_tail(&xprt->sc_dto_q, &dto_xprt_q);
+ }
spin_unlock_irqrestore(&dto_lock, flags);
/* Tasklet does all the work to avoid irqsave locks. */
@@ -611,6 +615,7 @@ static int rdma_cma_handler(struct rdma_cm_id *cma_id,
switch (event->event) {
case RDMA_CM_EVENT_ESTABLISHED:
/* Accept complete */
+ svc_xprt_get(xprt);
dprintk("svcrdma: Connection completed on DTO xprt=%p, "
"cm_id=%p\n", xprt, cma_id);
clear_bit(RDMAXPRT_CONN_PENDING, &rdma->sc_flags);
@@ -661,15 +666,15 @@ static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
listen_id = rdma_create_id(rdma_listen_handler, cma_xprt, RDMA_PS_TCP);
if (IS_ERR(listen_id)) {
- rdma_destroy_xprt(cma_xprt);
+ svc_xprt_put(&cma_xprt->sc_xprt);
dprintk("svcrdma: rdma_create_id failed = %ld\n",
PTR_ERR(listen_id));
return (void *)listen_id;
}
ret = rdma_bind_addr(listen_id, sa);
if (ret) {
- rdma_destroy_xprt(cma_xprt);
rdma_destroy_id(listen_id);
+ svc_xprt_put(&cma_xprt->sc_xprt);
dprintk("svcrdma: rdma_bind_addr failed = %d\n", ret);
return ERR_PTR(ret);
}
@@ -678,8 +683,9 @@ static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
ret = rdma_listen(listen_id, RPCRDMA_LISTEN_BACKLOG);
if (ret) {
rdma_destroy_id(listen_id);
- rdma_destroy_xprt(cma_xprt);
+ svc_xprt_put(&cma_xprt->sc_xprt);
dprintk("svcrdma: rdma_listen failed = %d\n", ret);
+ return ERR_PTR(ret);
}
/*
@@ -820,6 +826,7 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
newxprt->sc_sq_depth = qp_attr.cap.max_send_wr;
newxprt->sc_max_requests = qp_attr.cap.max_recv_wr;
}
+ svc_xprt_get(&newxprt->sc_xprt);
newxprt->sc_qp = newxprt->sc_cm_id->qp;
/* Register all of physical memory */
@@ -891,8 +898,15 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
errout:
dprintk("svcrdma: failure accepting new connection rc=%d.\n", ret);
+ /* Take a reference in case the DTO handler runs */
+ svc_xprt_get(&newxprt->sc_xprt);
+ if (newxprt->sc_qp && !IS_ERR(newxprt->sc_qp)) {
+ ib_destroy_qp(newxprt->sc_qp);
+ svc_xprt_put(&newxprt->sc_xprt);
+ }
rdma_destroy_id(newxprt->sc_cm_id);
- rdma_destroy_xprt(newxprt);
+ /* This call to put will destroy the transport */
+ svc_xprt_put(&newxprt->sc_xprt);
return NULL;
}
@@ -919,54 +933,60 @@ static void svc_rdma_release_rqst(struct svc_rqst *rqstp)
rqstp->rq_xprt_ctxt = NULL;
}
-/* Disable data ready events for this connection */
+/*
+ * When connected, an svc_xprt has at least three references:
+ *
+ * - A reference held by the QP. We still hold that here because this
+ * code deletes the QP and puts the reference.
+ *
+ * - A reference held by the cm_id between the ESTABLISHED and
+ * DISCONNECTED events. If the remote peer disconnected first, this
+ * reference could be gone.
+ *
+ * - A reference held by the svc_recv code that called this function
+ * as part of close processing.
+ *
+ * At a minimum two references should still be held.
+ */
static void svc_rdma_detach(struct svc_xprt *xprt)
{
struct svcxprt_rdma *rdma =
container_of(xprt, struct svcxprt_rdma, sc_xprt);
- unsigned long flags;
-
dprintk("svc: svc_rdma_detach(%p)\n", xprt);
- /*
- * Shutdown the connection. This will ensure we don't get any
- * more events from the provider.
- */
+
+ /* Disconnect and flush posted WQE */
rdma_disconnect(rdma->sc_cm_id);
- rdma_destroy_id(rdma->sc_cm_id);
- /* We may already be on the DTO list */
- spin_lock_irqsave(&dto_lock, flags);
- if (!list_empty(&rdma->sc_dto_q))
- list_del_init(&rdma->sc_dto_q);
- spin_unlock_irqrestore(&dto_lock, flags);
+ /* Destroy the QP if present (not a listener) */
+ if (rdma->sc_qp && !IS_ERR(rdma->sc_qp)) {
+ ib_destroy_qp(rdma->sc_qp);
+ svc_xprt_put(xprt);
+ }
+
+ /* Destroy the CM ID */
+ rdma_destroy_id(rdma->sc_cm_id);
}
static void svc_rdma_free(struct svc_xprt *xprt)
{
struct svcxprt_rdma *rdma = (struct svcxprt_rdma *)xprt;
dprintk("svcrdma: svc_rdma_free(%p)\n", rdma);
- rdma_destroy_xprt(rdma);
- kfree(rdma);
-}
-
-static void rdma_destroy_xprt(struct svcxprt_rdma *xprt)
-{
- if (xprt->sc_qp && !IS_ERR(xprt->sc_qp))
- ib_destroy_qp(xprt->sc_qp);
-
- if (xprt->sc_sq_cq && !IS_ERR(xprt->sc_sq_cq))
- ib_destroy_cq(xprt->sc_sq_cq);
+ /* We should only be called from kref_put */
+ BUG_ON(atomic_read(&xprt->xpt_ref.refcount) != 0);
+ if (rdma->sc_sq_cq && !IS_ERR(rdma->sc_sq_cq))
+ ib_destroy_cq(rdma->sc_sq_cq);
- if (xprt->sc_rq_cq && !IS_ERR(xprt->sc_rq_cq))
- ib_destroy_cq(xprt->sc_rq_cq);
+ if (rdma->sc_rq_cq && !IS_ERR(rdma->sc_rq_cq))
+ ib_destroy_cq(rdma->sc_rq_cq);
- if (xprt->sc_phys_mr && !IS_ERR(xprt->sc_phys_mr))
- ib_dereg_mr(xprt->sc_phys_mr);
+ if (rdma->sc_phys_mr && !IS_ERR(rdma->sc_phys_mr))
+ ib_dereg_mr(rdma->sc_phys_mr);
- if (xprt->sc_pd && !IS_ERR(xprt->sc_pd))
- ib_dealloc_pd(xprt->sc_pd);
+ if (rdma->sc_pd && !IS_ERR(rdma->sc_pd))
+ ib_dealloc_pd(rdma->sc_pd);
- destroy_context_cache(xprt->sc_ctxt_head);
+ destroy_context_cache(rdma->sc_ctxt_head);
+ kfree(rdma);
}
static int svc_rdma_has_wspace(struct svc_xprt *xprt)
--
1.5.4.rc2.60.gb2e62
--
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