Quoting r. Roland Dreier <[EMAIL PROTECTED]>:
> I'm pretty sure that any scheme that tries to use module reference
> counting will either be horribly complex, still have subtle races, or
> (mostly likely) both.
Actually, it turned out to be the simplest solution - and quite
elegant since there's no room for mistakes: if query is going to be running
this means module is still loaded so we can take a reference to it
without races.
As a bonus, and assertion inside __module_get increases the chance to catch
races where user forgets to cancel the query - much nicer than crashing
randomly.
Please take a look, if OK I'll build a similiar patch for ib_addr.
Warning: compile-tested only.
---
Make sure callback module isn't unloaded while callback is running.
Signed-off-by: Michael S. Tsirkin <[EMAIL PROTECTED]>
Index: linux-2.6.16/drivers/infiniband/include/rdma/ib_sa.h
===================================================================
--- linux-2.6.16/drivers/infiniband/include/rdma/ib_sa.h (revision 6281)
+++ linux-2.6.16/drivers/infiniband/include/rdma/ib_sa.h (working copy)
@@ -262,6 +262,7 @@
struct ib_sa_path_rec *resp,
void *context),
void *context,
+ struct module *owner,
struct ib_sa_query **query);
int ib_sa_mcmember_rec_query(struct ib_device *device, u8 port_num,
@@ -273,6 +274,7 @@
struct ib_sa_mcmember_rec *resp,
void *context),
void *context,
+ struct module *owner,
struct ib_sa_query **query);
int ib_sa_service_rec_query(struct ib_device *device, u8 port_num,
@@ -284,6 +286,7 @@
struct ib_sa_service_rec *resp,
void *context),
void *context,
+ struct module *owner,
struct ib_sa_query **sa_query);
/**
@@ -319,13 +322,14 @@
struct ib_sa_mcmember_rec *resp,
void *context),
void *context,
+ struct module *owner,
struct ib_sa_query **query)
{
return ib_sa_mcmember_rec_query(device, port_num,
IB_MGMT_METHOD_SET,
rec, comp_mask,
timeout_ms, gfp_mask, callback,
- context, query);
+ context, owner, query);
}
/**
@@ -361,13 +365,14 @@
struct ib_sa_mcmember_rec *resp,
void *context),
void *context,
+ struct module *owner,
struct ib_sa_query **query)
{
return ib_sa_mcmember_rec_query(device, port_num,
IB_SA_METHOD_DELETE,
rec, comp_mask,
timeout_ms, gfp_mask, callback,
- context, query);
+ context, owner, query);
}
/**
Index: linux-2.6.16/drivers/infiniband/core/at.c
===================================================================
--- linux-2.6.16/drivers/infiniband/core/at.c (revision 6281)
+++ linux-2.6.16/drivers/infiniband/core/at.c (working copy)
@@ -220,6 +220,7 @@
GFP_KERNEL,
ats_op_complete,
ib_dev,
+ THIS_MODULE,
&ib_dev->sa_query);
if (ib_dev->sa_id < 0) {
@@ -1122,6 +1123,7 @@
GFP_KERNEL,
ats_ips_req_complete,
req,
+ THIS_MODULE,
&req->pend.sa_query);
if (req->pend.sa_id < 0) {
@@ -1167,6 +1169,7 @@
GFP_KERNEL,
ats_route_req_complete,
req,
+ THIS_MODULE,
&req->pend.sa_query);
if (req->pend.sa_id < 0) {
@@ -1230,6 +1233,7 @@
GFP_KERNEL,
path_req_complete,
req,
+ THIS_MODULE,
&req->pend.sa_query);
if (req->pend.sa_id < 0) {
Index: linux-2.6.16/drivers/infiniband/core/sa_query.c
===================================================================
--- linux-2.6.16/drivers/infiniband/core/sa_query.c (revision 6281)
+++ linux-2.6.16/drivers/infiniband/core/sa_query.c (working copy)
@@ -73,6 +73,7 @@
struct ib_sa_query {
void (*callback)(struct ib_sa_query *, int, struct ib_sa_mad *);
void (*release)(struct ib_sa_query *);
+ struct module *owner;
struct ib_sa_port *port;
struct ib_mad_send_buf *mad_buf;
struct ib_sa_sm_ah *sm_ah;
@@ -559,6 +560,7 @@
* @callback:function called when query completes, times out or is
* canceled
* @context:opaque user context passed to callback
+ * @owner:callback owner module
* @sa_query:query context, used to cancel query
*
* Send a Path Record Get query to the SA to look up a path. The
@@ -580,6 +582,7 @@
struct ib_sa_path_rec *resp,
void *context),
void *context,
+ struct module *owner,
struct ib_sa_query **sa_query)
{
struct ib_sa_path_query *query;
@@ -614,6 +617,7 @@
init_mad(mad, agent);
query->sa_query.callback = callback ? ib_sa_path_rec_callback : NULL;
+ query->sa_query.owner = owner;
query->sa_query.release = ib_sa_path_rec_release;
query->sa_query.port = port;
mad->mad_hdr.method = IB_MGMT_METHOD_GET;
@@ -696,6 +700,7 @@
struct ib_sa_service_rec *resp,
void *context),
void *context,
+ struct module *owner,
struct ib_sa_query **sa_query)
{
struct ib_sa_service_query *query;
@@ -735,6 +740,7 @@
init_mad(mad, agent);
query->sa_query.callback = callback ? ib_sa_service_rec_callback : NULL;
+ query->sa_query.owner = owner;
query->sa_query.release = ib_sa_service_rec_release;
query->sa_query.port = port;
mad->mad_hdr.method = method;
@@ -793,6 +799,7 @@
struct ib_sa_mcmember_rec *resp,
void *context),
void *context,
+ struct module *owner,
struct ib_sa_query **sa_query)
{
struct ib_sa_mcmember_query *query;
@@ -827,6 +834,7 @@
init_mad(mad, agent);
query->sa_query.callback = callback ? ib_sa_mcmember_rec_callback :
NULL;
+ query->sa_query.owner = owner;
query->sa_query.release = ib_sa_mcmember_rec_release;
query->sa_query.port = port;
mad->mad_hdr.method = method;
@@ -866,13 +874,19 @@
/* No callback -- already got recv */
break;
case IB_WC_RESP_TIMEOUT_ERR:
+ __module_get(query->owner);
query->callback(query, -ETIMEDOUT, NULL);
+ module_put(query->owner);
break;
case IB_WC_WR_FLUSH_ERR:
+ __module_get(query->owner);
query->callback(query, -EINTR, NULL);
+ module_put(query->owner);
break;
default:
+ __module_get(query->owner);
query->callback(query, -EIO, NULL);
+ module_put(query->owner);
break;
}
@@ -895,6 +909,7 @@
query = mad_buf->context[0];
if (query->callback) {
+ __module_get(query->owner);
if (mad_recv_wc->wc->status == IB_WC_SUCCESS)
query->callback(query,
mad_recv_wc->recv_buf.mad->mad_hdr.status ?
@@ -902,6 +917,7 @@
(struct ib_sa_mad *)
mad_recv_wc->recv_buf.mad);
else
query->callback(query, -EIO, NULL);
+ module_put(query->owner);
}
ib_free_recv_mad(mad_recv_wc);
Index: linux-2.6.16/drivers/infiniband/core/cma.c
===================================================================
--- linux-2.6.16/drivers/infiniband/core/cma.c (revision 6281)
+++ linux-2.6.16/drivers/infiniband/core/cma.c (working copy)
@@ -1065,7 +1065,8 @@
IB_SA_PATH_REC_DGID | IB_SA_PATH_REC_SGID |
IB_SA_PATH_REC_PKEY | IB_SA_PATH_REC_NUMB_PATH,
timeout_ms, GFP_KERNEL,
- cma_query_handler, work, &id_priv->query);
+ cma_query_handler, work, THIS_MODULE,
+ &id_priv->query);
return (id_priv->query_id < 0) ? id_priv->query_id : 0;
}
Index: linux-2.6.16/drivers/infiniband/ulp/ipoib/ipoib_main.c
===================================================================
--- linux-2.6.16/drivers/infiniband/ulp/ipoib/ipoib_main.c (revision 6281)
+++ linux-2.6.16/drivers/infiniband/ulp/ipoib/ipoib_main.c (working copy)
@@ -472,7 +472,7 @@
IB_SA_PATH_REC_PKEY,
1000, GFP_ATOMIC,
path_rec_completion,
- path, &path->query);
+ path, THIS_MODULE, &path->query);
if (path->query_id < 0) {
ipoib_warn(priv, "ib_sa_path_rec_get failed\n");
path->query = NULL;
Index: linux-2.6.16/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
===================================================================
--- linux-2.6.16/drivers/infiniband/ulp/ipoib/ipoib_multicast.c (revision 6281)
+++ linux-2.6.16/drivers/infiniband/ulp/ipoib/ipoib_multicast.c (working copy)
@@ -367,7 +367,7 @@
IB_SA_MCMEMBER_REC_JOIN_STATE,
1000, GFP_ATOMIC,
ipoib_mcast_sendonly_join_complete,
- mcast, &mcast->query);
+ mcast, THIS_MODULE, &mcast->query);
if (ret < 0) {
ipoib_warn(priv, "ib_sa_mcmember_rec_set failed (ret = %d)\n",
ret);
@@ -487,7 +487,7 @@
ret = ib_sa_mcmember_rec_set(priv->ca, priv->port, &rec, comp_mask,
mcast->backoff * 1000, GFP_ATOMIC,
ipoib_mcast_join_complete,
- mcast, &mcast->query);
+ mcast, THIS_MODULE, &mcast->query);
if (ret < 0) {
ipoib_warn(priv, "ib_sa_mcmember_rec_set failed, status %d\n",
ret);
@@ -686,7 +686,7 @@
IB_SA_MCMEMBER_REC_PKEY |
IB_SA_MCMEMBER_REC_JOIN_STATE,
0, GFP_ATOMIC, NULL,
- mcast, &mcast->query);
+ mcast, THIS_MODULE, &mcast->query);
if (ret < 0)
ipoib_warn(priv, "ib_sa_mcmember_rec_delete failed "
"for leave (result = %d)\n", ret);
Index: linux-2.6.16/drivers/infiniband/ulp/srp/ib_srp.c
===================================================================
--- linux-2.6.16/drivers/infiniband/ulp/srp/ib_srp.c (revision 6281)
+++ linux-2.6.16/drivers/infiniband/ulp/srp/ib_srp.c (working copy)
@@ -260,7 +260,8 @@
SRP_PATH_REC_TIMEOUT_MS,
GFP_KERNEL,
srp_path_rec_completion,
- target, &target->path_query);
+ target, THIS_MODULE,
+ &target->path_query);
if (target->path_query_id < 0)
return target->path_query_id;
--
MST
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